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Anthropic Principle

Giuseppe Tanzella-Nitti

I. From the Copernican to the Anthropic Principle - II. The Scientific Observations at the basis of the Anthropic Principle - III. The Interpretation of Scientific Data and the Most Significant Philosophical Key-Points 1. The Distinction between WAP and SAP . 2. The Objections to the Anthropic Principle and their Philosophical Value . 3. The True Scientific Significance of the Anthropic Principle . - IV. The Anthropic Principle between Science and Religion: is there any Design in the Cosmos? 1. Anthropic Principle and “Argument from Design”. 2. The Peculiarity of the Anthropic Principle among the Various Arguments from Design . 3. Anthropic Principle and Christian Theology of Creation . - V. Anthropic Principle and Theological Christocentrism. 1. Unity and Coherence of the Cosmos under a Christocentric Perspective. 2. The Paradox of the Cosmos and the Mystery of the Risen Christ .

One of the most important changes that characterized the transition from the Medieval epoch to the Modern Age was the progressive displacement of the human being from a central position in the cosmos, and the consequent loss of many philosophical privileges historically associated with that. From the Copernican revolution onwards, responsible for such a decentralization are in the first place the natural sciences, primarily physics, due to the development of modern and contemporary cosmology, and then biology, due to the discovery of the evolution of the species. The new perspectives caused by the loss of the observer's cosmic central position were certainly in tune with the demands for objectivity and impersonal analysis required by the rising scientific method, and by then recognized as one of the pillars of the new scientific epistemology. Once projected on this historical and methodological background, the set of results and reflections today known as the “Anthropic Principle” show all their surprising novelty. Since the beginning of the Modern Age, they stand now as the first attempt to show that, when handing back a more central role to humankind, we can unexpectedly achieve a better scientific understanding of the universe, of its properties and evolution.

The fact that the attempt to restore the significance of the presence of humanity within the cosmos comes from results alleged by the natural sciences, and not simply on the basis of considerations developed in the domains of psychology or cognitive science, has offered elements of dialogue and debate with respect to philosophy and religion. In fact, these have always been less inclined than the natural sciences to accept that loss of centrality. Just second to the so-called “problem of the origins”, the debate that the Anthropic Principle has raised in the last decades constitutes a major issue for interdisciplinary discussion between science, philosophy and theology. Although the Anthropic Principle regards principally the field of cosmology, its suggestions extend into the field of biology, where they meet some recent demands for overcoming the Darwinian paradigm. These two streams are by now giving rise to a new, overall understanding of nature and life, that some authors have labelled “intelligent design”. We are dealing here with reflections made in the domains of science, but that enter into an open terrain of confrontation with philosophy and religion.

I. From the Copernican Principle to the Anthropic Principle

It is usual to refer to the name of  Nicholas Copernicus (1473-1543) to indicate the beginning of the cosmological and philosophical decentralization of the human being occurred in the Modern Age. Nevertheless, such a loss of centrality showed non-univocal aspects and had a non-linear historical development, especially if it is evaluated over the background of its implications for religious thought. A writer such as Nicholas of Cusa (1401-1464), for instance, had no difficulty in maintaining a non-geocentric, philosophical and cosmological position, without any contrast for theology. It was not the same for a thinker such as Giordano Bruno (1548-1600), whose intention, probably, was not that of finding a way for a non-controversial synthesis. Moreover, the progressive emancipation of humankind and nature from God was, in part, an unwanted outcome of a process that had one of its principal roots in humanistic anthropocentrism, a movement whose first purpose was not to refuse or overcome theology. The protagonists of the Copernican cosmological revolution, from Copernicus to Galileo, from Kepler to Newton, were far from interpreting this revolution in an anti-religious manner. On their part, not even the humanists of the Renaissance wanted to pursue an anti-religious program when re-evaluating all of the human world, although part of 16th and 17th century philosophy ended by placing between parentheses the bond between humankind, and its moral life, and God (Machiavelli, Montaigne, van Groot, Hobbes). An author who summarizes in himself the double soul, and therefore the genetic ambiguity, of the anthropocentrism of the beginning of the Modern Age was, without any doubt,  René Descartes (1596-1650). His gnoseology wanted to remain theist, but, choosing as its starting point the human psyche, he was putting the basis of a future understanding of the world without God.

After the Copernican Principle had sanctioned how the Earth would not occupy any longer a privileged observational position, the scientific method began to put in light the existence of the so-called “Principle of covariance”, according to which the laws of nature and the principles of the experimental sciences must be valid for all the observers. This implied the methodical recognizing, and the consequent removal, of any privileged conditions owned by him or her who realizes an experiment or makes a certain scientific observation. By soon science understood how important was to deal with reproducible phenomena, that is, phenomena that anyone could verify and whose measurements could be object of inter-subjective communication. Science was then concerned in refining ever and ever the formulation of protocols to regulate an always more objective and impersonal knowledge. The involvement and the implication of the observer within scientific activity came to light only in the 20th century: in the field of physics with quantum mechanics; in epistemology with the introduction of the mutual, critical implications between theory and observation; and lastly in the field of gnoseology, with the rediscovery of personal, implicit, and heuristic factors, tacitly present in every scientific knowledge (  EPISTEMOLOGY, II).

Modern cosmology, whose object of study in now the physical universe in its totality, has implemented a definite extension of the Copernican principle and of the Principle of covariance through the formulation of the “Cosmological principle”. According to the Cosmological principle, we must consider as a non-privileged position not only the position of any scientific observer on the Earth, or that of the Earth itself within the solar system, but whatever observational position in the whole of the universe. Perhaps, an interesting anticipation of such a principle could be found again in Nicholas of Cusa, when he affirmed that the universe would not have any fixed center but every point would be its center (cf. De docta ignorantia , book II, ch. XI). In other words, according to the Cosmological principle, every point of the universe is adequate to describe the physical universe, its structure and its laws, in a universally valid fashion. Nevertheless, such a principle is entirely valid only for a certain cosmological “model”, those corresponding to a homogeneous and isotropic universe, in which the study of the space-time on medium and large scale, can legitimately leave out of consideration possible dishomogeneities and non-uniformity on a small and local scale. A number of facts show that dishomogeneities on small and intermediate scales are not so relevant as to contradict the homogeneity of the universe on a large scale, i.e. on a “cosmological” scale, thus permitting the cosmological principle to function effectively. They are, for instance: the outcome that the same laws of nature discovered on the Earth are true also for larger distances within the solar system and in the Milky Way galaxy, and even on an extra-galactic scale; the isotropy and symmetry of the background microwave thermal radiation; the morphological structure of the clusters of galaxies. The Cosmological principle works indeed also within an expanding universe. In fact, it is easy to demonstrate that no point of the universe is privileged within a regime of isotropic expansion (i.e., an expansion whose properties are identical in all directions), and that the expansion can be equivalently described from every point in the universe. A “perfect Cosmological principle”, a radicalization of the Cosmological principle, claims that all the magnitudes and properties of the universe should be identical if observed not only in whatever spatial point, but also in whatever instant of time. However, a perfect Cosmological principle does not seem to work. We know that many parameters of the universe (density, radius or temperature, for example) vary according to time-dependent laws, even though such temporal variations and the laws that describe them are the same in every point of the universe in which they are measured. A perfect Cosmological principle would ask that the expansion of the universe were counter-balanced by the continual creation of new matter and energy, in a way that assures the constancy in time of the global parameters of the universe, such as its overall structure or the distribution of the matter it contains. This hypothesis of continual creation, however, is a conjecture that the present observations rule out with a good level of confidence.

Prior to the present, it has never been claimed that the presence of humankind could play any relevant role in this process of understanding the cosmos and its history. Humankind certainly belongs to the “cosmic system”, i.e. the subject matter of cosmology, but the slight consistency of our cosmic coordinates —geometric, chemical and biological— do not seem to possess any influence on the structure and evolution of the universe in its entirety, especially if the space and time scales of the Earth, and that of the life that it hosts, are evaluated on the background of the great and vast cosmological scale of the whole physical universe. It has been in the last decades of the 20th century when some new reflections, rising from within scientific research, have suggested something profoundly different. If it remains always true that human beings do not occupy any “central” position (geometrically or physically) within the cosmos, they do however seem to occupy a “privileged” position. What, then, would this privilege consist of? It has been discovered that the fundamental physical parameters that determined both the structure and the physical-chemical laws of the universe, like the delicate dependence of its evolutionary phases upon each other, responsible for having progressively supplied adequate chemical abundances and regulated the formation of stars and planets, have been precisely also those parameters necessary to host life, and eventually intelligent observers. And, what is more, many of these delicate conditions did not occur so much in the course of the temporal development of the cosmos as they did during the very early moments of its primeval formation and of its subsequent accelerated expansion. This ensemble of scientific results and observations, that I will examine in more detail below (see section II), has prompted some authors, mainly coming from the scientific, astronomical community, to propose the formulation of what is today known as “Anthropic Principle”.

Collecting some suggestions of Dirac (1937), who pointed out some interesting numerical coincidences existing between the relevant values for the global properties of the cosmos (for example the relationships between the total number of photons and barions, the intensity of the electrical and gravitational forces, the age and dimensions of the universe expressed in atomic units), and reminding himself of the indication of Dicke (1961), who emphasized that the presence of life strongly conditions the value assumed by some cosmological “observed” magnitudes, which cannot be very different from the real measured ones, it was Brandon Carter (1974) who first proposed a coherent presentation of such observations employing the expression Anthropic Principle. As he specified later, his intentions were to place the accent on the human being “as observer”, without wanting to make any consideration of a strictly philosophical value. Carter introduced the formulation of his Anthropic Principle with two different variations, weak and strong . The “weak” formulation states that the values of some specific cosmological parameters can only be those that are compatible with the existence of observers in the universe; the “strong” formulation of the Anthropic Principle affirms that the universe must possess only those properties and parameters which determine, in some stage of its development, the birth and then the presence of observers. Carter emphasized the “novelty” of this perspective underlining that the introduction of the Principle in a scientific context was legitimated by its capacity of predictability, analogously to what happens for other principles or theories commonly used in physics or astrophysics.

Some years later, John Barrow and Frank Tipler, authors of their ponderous work The Anthropic Cosmological Principle (1986) have theorized the Anthropic Principle in a broader and more systematic way, proposing three precise versions, that, in fact, have conditioned nearly all the following debates regarding the theme. According to their formulation of the Weak Anthropic Principle (WAP), «the observed values of all physical and cosmological quantities are not equally probable but they take on values restricted by the requirement that there exist sites where carbon-based life can evolve and by the requirement that the Universe be old enough for it to have already done so» (Barrow and Tipler, 1986, p. 16). The use of a Strong Anthropic Principle (SAP) indicated instead that «The Universe must have those properties which allow life to develop within it at some stage in its history» ( ibidem , p 21). To this last formulation can correspond one that includes the perspective of quantum cosmology ( Participatory Anthropic Principle ); in this case, the “necessity” of the observer is stated in order that our present universe is selected from an ensemble of possible universes (different quantum states), and then comes into being (actual state) . In the systematization given by Barrow and Tipler, the Strong Anthropic Principle would finally lead, as its extreme consequence, to a Final Anthropic Principle (FAP), according to which «intelligent information-processing must come into existence in the Universe, and, once it comes into existence, it will never die out» ( ibidem , p. 23).

Prior to analyzing the philosophy brought along with the Anthropic Principle and its possible theological resonances, it is not superfluous to elucidate that both the denomination of “principle”, and its qualification to be “anthropic”, do not appear obvious. If no supplementary explanations are provided, an approach to its formulation (strong or weak) shows a certain tautological character of the Principle. It says that, for one or more conclusions in the astrophysical or cosmological domain to be true, they must be compatible with the observations, and among these observations we have to include also the existence of the observer itself (cf. Swinburne, 1990). Regarding the adjective “anthropic”, in the strong formulation, the emphasis of the Principle puts into first place the observer since he or she is the “receptor of the information of the universe”, and only secondarily on the conditions of being human. In the “weak” form, instead, the Principle underlines the necessary existence of conditions to produce chemical-biological niches adequate for the appearance of life, but not necessarily for the human life. To qualify it as “anthropic” assumes an implicit, non-obvious link, between the appearance of life and human life, considering this last to be the “natural” outlet for the cosmic evolutionary process, whether it is physical or chemical-biological.

In all cases, a philosophical discussion of the Principle should always be preceded by an analysis of the scientific data on which it is based (section II), in order to evaluate its independence from further philosophical paradigms, especially of an aprioristic kind, and to clarify the real philosophical implications that this data can generate (Section III); this is particularly crucial if we want to point out and clarify possible links with the perspectives of natural theology and Christian Revelation (Sections IV and V). It is worthwhile noting that the interdisciplinary debate that the Anthropic Principle has provoked and continues to provoke, witnesses an important hermeneutic and epistemological turning-point. The reflection of the sciences on the cosmos seems obliged to call into question again the role of the knowing subject; and this does not happen in the context of a simple theory of measurement, or in the context of a generic subject/object interaction; it happens now within the framework of a global inquiry regarding the nature and the significance of the cosmos in its entirety. The remark made by J. Merleau-Ponty (1984), according to whom the Anthropic Principle represents a significant epistemological turning-point in the philosophy of 20th century science, thanks to its capacity to open again the discussion with respect to the non-accidental role that humankind plays within the physical understanding of the universe, should be fully endorsed. Physical cosmology is obliged to review some of its principles because they are recognized to be interlaced with questions of a metaphysical character, opening again the way to a new possible integration between the natural and human sciences.

II. The Scientific Observations at the basis of the Anthropic Principle

There exist many works providing valuable presentations of the scientific data at the basis of the Anthropic Principle. Many of them have a synthetic and popular-science character, others are extensive specialized books (cf. Barrow and Tipler, 1986; Leslie, 1989; Gribbin and Rees, 1989; Demaret and Lambert, 1994), or scientific review articles (cf. Leslie, 1988). There also exists a high number of collected essays and articles expressly dedicated to the theme, often published as Proceedings of Conferences (cf. for example Bertola and Curi, 1993). The essential original works, that contain the kernel of the observations which suggested the introduction of the Principle, are the scientific articles of Dicke (1961), Carter (1974), Carr and Rees (1979), and the huge amount of data offered by the previously cited book of Barrow and Tipler (1986).

The reflections start off by noting the importance and the delicacy of the values of the four natural constants that regulate the intensity of the interaction of the four fundamental forces, respectively α_g (gravitational), α (electromagnetic), α_w(electro-weak nuclear), and α_s(strong nuclear), demonstrating how the structure of each body — elementary particles, biological molecules, the different size of the living beings, up until the planets, stars and galaxies— have a dimensional structure (sizes and masses) that sensitively depend upon these constants. In particular, the mass M or the dimension R of any physical body can be expressed as a function of a typical mass and radius multiplied by the four natural constants to the power of a certain exponent. It allows that each natural structure lays down, within the diagram log R – log M, inside a strict, well defined band. Such a result does not shed any light on the particular “anthropic” conditions, but simply indicates the importance that the four natural constants have regarding the structuring of the cosmos. It can be observed that these four constants are adimensional, that is they do not depend upon any particular system of measurement we choose, being pure numbers. The value of the ratio between two of these constants expresses the ratio of the intensities between the two corresponding forces, regulating the way in which, varying the distance between two bodies, one prevails with respect to the other (remember that they can act in a competitive fashion, as happens for example, with the positive protons in an atomic nucleus: the electromagnetic force tends to drive back the protons because they are charges of the same sign, while strong nuclear force, on a very short scale, tends to attract the protons). The mathematical formulas that express the value of the four constants of nature depend upon other mathematical (such as π) or physical (non-adimensional) constants, like the mass of the proton m_p, the charge on the electron e , the universal constant of gravitation G , Planck's constant h , and the velocity of light in the vacuum c .

The values of the natural constants are in a certain way “congenital” to the coming into being of the universe (   COSMOLOGY, II). We ignore which kind of physics is apt to describe the universe prior to «Planck’s era», when its dimensions were smaller than 10^-33 cm , and the time from the beginning of its expansion was less than 10^-43 sec. What we know is that when the fundamental forces separated by means of progressive “breaks of symmetry”, their corresponding constants remained “fixed”; this happened within the first 10^-6 sec, that is the epoch starting from which the first components of matter (quarks and anti-quarks) and of radiation (photons) quickly gave origin, well inside the first second of the “life” of the universe, to the elementary particles that are known today.

Such constants (we could reasonably add also the adimensional ratio of the proton/electron mass) are associated with a number of important and delicate conditions that will determine the “possibility” that, along the cosmic evolution, the universe takes one way instead of another. Not all the ways can bring about the physical-chemical conditions necessary for life, but only those corresponding to some specific and very limited “numerical windows”. Among all these conditions, I summarize here which seem to be the most important.

After about 1 sec of time from the beginning of the expansion ( Big Bang ), neutrinos decoupled from the rest of the matter, so “freezing” the ratio between the number of protons and the neutrons, that until that moment were subject to continuing transformation p n. Such a frozen ratio depends very sensitively upon the modality of the expansion (that is, upon α_g) and on the intensity of the weak interaction, that regulated the decay of the neutron (that is, upon α_w). The formation of “cosmological” helium (that is, helium originated during the Big Bang , not in the stars;   COSMOLOGY, IV) strongly depends upon the relationship between the total number of protons and neutrons and, therefore, upon the value of the ratio α_g/α_w. If this ratio had been lightly superior, all the hydrogen (protons) would be transformed into nuclei of helium, with easily imaginable consequences, among them the impossibility to have water, that is composed of hydrogen. If it had been lightly inferior we would not have any abundance of cosmological helium, causing strong negative repercussions for the subsequent thermodynamic evolution of the stars; in fact, without any percentage of cosmological helium the evolving times of stars would have resulted extremely rapid, in a way that the time of existence of the star becomes incompatible with the time requested for the development of life on the planets. The value of α_galso regulated the initial rate of expansion of the universe: if its value had been just a little bit higher than the actual, it would have implicated the collapse of the whole universe on itself, more or less immediately, therefore preventing any following “development of the facts”; on the other hand, a value just a little bit lower, would have prevented the subsequent formation of any gravitational aggregation of matter, thereby inhibiting the formation of galaxies and stars and, a fortiori , of planets.

Also the ratio a α_s/α is rather critical in order to the development of a chemistry adequate for life. The strong nuclear force, driven by α_s, and the electromagnetic force, driven by a, act in an opposite directions (respectively attracting and repelling) in the atomic nuclei composed by protons. Their equilibrium, prevailing the strong nuclear force in the interactions at a very short range, make possible the existence and stability of atomic nuclei, and allow the formation of a “periodic table” of chemical elements, such as we observe it today. If a had been just a little bit larger, or α_s a little bit smaller, even the lightest nuclei would not have been stable. The role played by this critical ratio also reflects on the sensitivity of the value of the elementary electrical charge e .

In the formation of the proto-stellar masses from the interstellar gas clouds it is necessary, in order to let them becoming true stars irradiating energy by thermonuclear fusion, that the gravitational collapse which will lead to the birth of a new star gets interrupted by the burst of nuclear reactions. This can happen only thanks to the favorable relationship between the value of α_gand the other physical constants involved in the phenomenon of the gravitational collapse. It surprisingly happens that the temperature, which constantly increases during the phase of contraction, reaches the threshold necessary for the nuclear reactions to take place, just before that the same collapse would drive the proto-star towards an irreversible equilibrium of degenerate gas, as happens in the final evolutionary states of white dwarfs or of neutron stars (around which no planets can support life). If such a threshold of temperature was not reached just on time, the universe would be populated by an extremely large number of “failed” stars, but not one energetically active star.

Another delicate condition regards the relationships among the constant of gravitational interaction α_g, that of electromagnetic interaction a , and the ratio between the proton and the electron mass. The adimensional values of these three constants make them such that the phases of stellar formation let the proto-stars to give origin, within the Temperature – Luminosity diagram (the so-called Hertzsprung-Russell diagram), to an ordered sequence of dwarf stars called “main sequence”. The stars slowly depart from this main sequence, as their energetic and thermonuclear evolution goes on. Those same constants also determine that the main sequence results formed by some stars having radiative equilibrium (in which the thermal energy is transported by radiation from the nucleus towards the external layers), and by other stars having convective equilibrium (where such a transport takes place, instead, by convection). The first ones, hot and energetic, evolve more rapidly and supply the interstellar medium with heavy chemical elements (including carbon, nitrogen and oxygen) synthesized in their nuclei; the second ones, are less bright and have a longer life, assuring the possibility that planets, eventually formed around them, have existing times long enough to let life develop and evolve. Life cannot appear on planets orbiting around radiative stars because their surfaces are too hot and bright; however, without these stars, life could neither originate elsewhere, because the interstellar medium would not be supplied with chemical elements adequate for life. Actually, to give origins to the biological molecules upon which life is based, the interstellar space had to be enriched with heavy chemical elements produced in the nuclei of stars. A relevant point is that, in order to render such elements available in the interstellar medium so that new stars and planets may form from such chemically-enriched gas clouds, it is necessary to have an efficient machinery to ejects chemical elements from the stars into the interstellar space. This machinery is provided if in the final phases of stellar evolution the outer star layers become unstable and get expelled into space, without collapsing in on themselves. In other words, we need a significant number of stars in each galaxy to die as supernovae , and not as white dwarfs or neutron stars. For that to happen, again, new delicate numerical constraints must be imposed to the values of α_g and of α_w. It is in fact required that the many neutrinos produced in the phase immediately preceding the gravitational collapse, which the instability of the star brings about, can interact with the gaseous layers of the star, pushing them violently towards the outer space, an event that occurs only if the rate of interaction and the rate of collapse, that are governed by the two constants above, are constructively compatible with each other.

To the various “conditions for life” summarized above, in which the numerical constraints can be expressed in terms of rigorous mathematical equations, we could append other additional observations. Though not directly linked to the values of the constants of nature, they also point out how “critical” many circumstances are in order to allow the formation of a chemistry adequate for life. One of them is the delicacy of the nuclear reactions which form carbon, through beryllium and helium (Be⁸ + He⁴ -> C¹²), and oxygen, through the capture of new helium nuclei (C¹² + He⁴ -> O¹⁶). In the first case, the existence of an opportune energy level of the excited carbon (7,65 Mev) close to the sum of the energy levels of beryllium and helium (7,37 Mev), turns out unexpectedly propitious to favor the carbon synthesis, since the beryllium-helium reaction has a very small cross section. In the second case, if the energy level of the oxygen (7,12 Mev) were not a bit lower than the sum of the energy levels of the two nuclei that produce it (7,16 Mev), almost all the carbon would be completely burnt to produce oxygen, preventing the development of a carbon-based life. Luckily for us, the beryllium, less important for life, is lost, and a good quantity of carbon, without which the whole biology would not be possible, is conserved. The formation of the crystals and the stability of the macromolecules are, moreover, also linked to the critical values of the ratio between the proton and electron masses and of the electrical charge e . Finally, it must not be forgotten that the water, so important for life, can be abundantly present at the liquid phase because the average temperature of the biosphere on the surface of the Earth actually falls within the tight interval between its freezing and boiling points (0- 100 °C ). The inventory of the delicate physical and chemical conditions considered “anthropic” could be even larger: Barrow and Tipler (1986) and Demaret and Lambert (1994) recorded various decades of them.

Summarizing up what we have rapidly sketched, these results indicate that a light variation of the numerical values of the constants of nature would have given (hypothetically) origins to a universe with a structure, distribution of the chemical-physical morphologies, and laws of nature, all dramatically different from the actual ones. This would have also interrupted the critical sequence of phenomena that, starting from the initial Big Bang, led to the existence of a physics (planets around stars with a convective equilibrium) and a chemistry (elements and molecules of biological interest) necessary for life. Such a sequence of phenomena appears moreover to depend, in an equally critical manner, upon numerous other conditions having more a structural, rather than an evolutionary character, that involves the properties of elementary particles, atomic energy levels, chemical bonds and the major physical constants. Finally, a remarkable result is that the numerical values of the constants of the four fundamental interactions are all already fixed within a time of about 10^-6 sec from the horizon of the Big Bang ; that is, at the time in which the electromagnetic force differentiates itself from the three remaining forces, and the properties of the protons and of the neutrons remain established once for ever. The “ensemble” of the above considerations is often summarized, and efficaciously expressed, saying that the essential characteristics of our universe appear finely tuned , that is accurately “regulated”, for the appearance of life.

III. The Interpretation of Scientific Data and the Most Significant Philosophical Key-Points

1. The Distinction between WAP and SAP. A first reflection prompted by the data is the need for clarifying the distinction existing between the weak (WAP) and the strong (SAP) versions of the Anthropic Principle. Various authors have rightly pointed out that the WAP appears to be a scientifically founded, but philosophically inconsequential, Principle (they emphasize the tautological character of the Principle, or simply the fact that it formulates a status de facto ), while the SAP looks as a scientifically groundless Principle, but with a very strong philosophical content. This distinction, I guess, looks particularly useful, both on the level of analysis of science and on the level of logic inference, although it is understandable that, on more general contexts of reflection, some authors consider the weak and the strong formulations forming a certain continuity. That the distinction between WAP and SAP must be maintained, at least along its general lines, is also suggested by the acknowledgement that in strictly scientific terms the weak formulation of the Principle asserts that the conditions and the observed coincidences are conditions that are necessary but not sufficient for the appearance of life, while the strong formulation states that we deal with conditions that are both necessary and sufficient . This last implication cannot be founded at the scientific level (scientific weakness of the strong formulation) simply because we do not know all the conditions and processes that, starting from the existence of a physics and a chemistry adequately tuned for hosting life in the universe (necessary conditions), might lead us to always and necessarily conclude that life effectively makes its appearance (sufficient conditions). In other words, the discovery of those delicate conditions, or also the finding of some physical-mathematical justification for them, is not equivalent to give the reason for why life exists and for what life is.

A second reflection is that a use of the WAP could not be associated, in reality, to the adjective “anthropic”, since the physical-chemical conditions it refers to do not involve humankind more than a daisy or an amoeba: they deal with conditions necessary to have an organic, carbon-based chemistry, and an adequate biology. A universe possessing the anthropic conditions indicated by the WAP, but without intelligent life, would be fully conceivable, with the only difference that it would not have any observer. On the contrary, the SAP presents itself with an undoubted philosophical charge, linking in a bi-univocal way the existence of the universe and that of humankind (as intelligent observer). The universe must exist only with just the characteristics that allow it to have intelligent observers somewhere. In other words, if the universe exists then humankind exists (the reverse proposition, of an idealistic type, is after all obvious). In the SAP formulation the finalistic dimension could not be even explicit, while its determinist dimension certainly is.

It would be worthwhile to clarify for a moment the emphasis placed by Carter, in his original proposal for a SAP, on humankind as an observer : «the Universe, and hence the fundamental parameters on which it depends, must be such as to admit the creation of observers within it at some stage. To paraphrase Descartes, “cogito ergo mundus talis est”» (Carter, 1974, p. 294). At this level, when the emphasis is placed on the observer , the SAP puts itself into continuity with the WAP: after all it takes its predicting value (and therefore its scientific value) from it, treating the presence of the observer as one of the observed data with which the structure of the cosmos must be consistent. The presence of an observer is, in fact, implicitly assumed also in the formulation of a simple WAP; and it could not be otherwise for any scientific observation. Things change if the SAP is philosophically read as having strong implications on the fact that the universe must be such as to necessarily have the presence of human beings. To arrive at such a conclusion starting from the scientific data only, does not seem to me compulsory. By itself, scientific method is incapable to give account of and justify all the sufficient conditions for the appearance of humankind; this would mean to define and determine, in an exhaustive way, the ultimate reasons for the whole human phenomenology (including knowledge and self-reflection). In doing so, science would implicitly endorse a highly reductive anthropological vision: understanding the human being would be the same as to know the reasons for its soma , ignoring the transcendence or emergence of the human psyche on the matter. In this respect, the Strong Anthropic Principle embodies a monist (materialist) solution of the  mind-body relationship and a strongly determinist vision of cosmic evolution. We deal here with an omni-comprehensive vision of reality, a vision claimed with absolute and universal necessity (and therefore on a metaphysical level), but directly extrapolated from reflections made with a relative, non absolute, necessity (on the level of physical sciences). Such interpretation was probably not the original understanding of Carter, but has finished up to impose itself as a dominant idea in the debate that followed his original claims, especially through the influx brought about by the reflections reported in the concluding chapter of the book by Barrow and Tipler (1986, cf. ch. 10).

2. The Objections to the Anthropic Principle and their Philosophical Value. Objections regarding the true significance of the Principle have been raised from both scientific and philosophical positions, and possible “solutions” of the Principle have been proposed accordingly. In the following discussion, I will refer to the “core” of the Principle, that is, to the coincidences and to the delicate conditions ( fine tuning ) pointed out by the scientific observations, abstracting for the moment from their diverse possible usage (weak or strong). I am commenting on three main critiques: a) the supposed tautological valence of the Principle; b) the existence of a general law of nature from which we can deduce the existence of the various anthropic coincidences (or biotic, if you prefer); and finally c) the resort to cosmological models, including quantum cosmology models, that predict a multiplicity of many or infinite universes ( many worlds models ). These three “solutions” are very often presented as arguments which rule out any “finalistic” usage of the Principle, a use that — as we have seen— does not necessarily descend (at least in a scientific position) from the simple presentation of the data, but is implicitly (and perhaps unconsciously) by now associated with the Anthropic Principle in many interdisciplinary debates.

The objection (a) regards the obviousness and triviality of the Principle. The latter would manifest, after all, something that could not be otherwise: that which exists does so only because it can exist. It would not have sense, for an apple broken off from the branch of a tree, to ask the fruit why the tree possesses those physical and biochemical laws that make the tree to be such as it is, and not otherwise: it turns out clear that only those laws allow the apple to rise such an “interrogation”. I believe that this argument, although correct, does not remove all the significance possessed by the principle. As pointed out since the time of  Wittgenstein, every logical or mathematical affirmation is, by its own, tautological in character, insofar as we accept a number of axioms and non-demonstrable propositions that make possible the beginning of the reasoning process. But in a certain sense it is no longer so when a logical sentence helps to better understand (with cognitive progress) the implications and the relations existing among the various elements of the whole, though it adds no new knowledge to the individual elements themselves (cf. Zycinski, 2001). The conditions and the coincidences represented by the fine tuning have a mathematical nature (and therefore they are tautological in part), but they also point to observable physical facts (and therefore to the world of facts, to employ a Wittgensteinean vocabulary). The many relations that the fine tuning express add a new knowledge to physics and to the properties of the cosmos, just like a tautological relation of identity a = a ' let new meanings and results emerge when we deepen the empirical contents of a (the whole of the anthropic conditions) and of a ' (the presence of the observer). To think that the existence of these conditions does not call for any “explanations” and must be taken as “mere facts”, without ever again asking for a successive deepening, would be equivalent, for example, to deny any significance to the affirmation «the sky at night is dark», considering it an obvious statement; today, we know instead that the nocturnal dark is not due to the absence of the sun, but to the expansion of the universe, in particular to the redshift associated with such expansion, that makes the light of all the stars in the sky weaker and not constructively integrated. Were it so, the nocturnal sky would have a lot more brightness than the sky illuminated by the sun (Olber's paradox). The motive of an observation that in the past was considered obvious, was in reality the action of a physical law that, once known, has increased the comprehension of a phenomenon previously accepted as something simply given.

The second critique (b) of the significance of the fine tuning claims that what appears today to be a coincidence or a set of exceptional conditions, might result later to be the necessary outcome of a much more general physical law. Presently, such law is still unknown in all its consistency, but the various anthropic conditions would descend from it as its physical consequence or one of its logical-numerical corollary. In a certain sense, this would lead the weak Anthropic Principle to be “absorbed” inside the strong formulation, that could now be expressed by saying that «the universe must have only the characters that bring about the presence of humankind, because there is a “general physical law” that actually implies this». This looks to be legitimate, because part of the work of science is to understand local properties and particular formulations in the light of more global and general interpretations. But when such a process of generalization arrives at its extreme limits, i.e. when it tries to understand the reason for all the properties and characteristics of the whole of reality, then physical cosmology faces again to the “problem of the whole”, a problem that scientific method cannot formalize in a complete and exhausting way. The situation is analogous to what happens when science tries to tackle the “problem of origins”: when cosmology attempts to give an account of the “ultimate why” — in the present case, questioning not only the motive of the properties of some individual entity, but the ultimate causes of all the reality — it drops the experimental method, to switch to conclusions that imply a major level of abstraction, proper to philosophy and metaphysics. In a few words, it is very possible that many of the anthropic conditions are necessary effects of broader and more general laws, but if we want to arrive at formulating an “omni-comprehensive cosmic super-law”, this does not belong anymore, ipso facto , to the domain of the natural sciences.

The third suggestion (c) invoked to “solve” the Anthropic Principle concerns the formulation of cosmological models that have recourse to multiple universes (   MANY-WORLDS MODELS, III). Some of the solutions that describe the state of the universe when passing from the Planck's era to its following transitions, foresee the production of an extraordinarily great number of independent regions of space-time during a rapid phase of inflation ( COSMOLOGY, III). Each of these regions would give origin to a universe with an actual set of values for the constants of nature, but only that universe (or those universes) with the “right” values will allow the development of life and eventually the presence of intelligent observers in it. Instead of “parallel” stories, a many-worlds model could even correspond to many universes, chronologically successive one after the other, having a new Big Bang every time the preceding universe has concluded its collapsing history into a Big Crunch. This theoretical option corresponds to one of the possible solutions for the standard Big Bang cosmological models, and it is known as the “cyclical universe” model. (   COSMOLOGY, V.2). Today, such solutions do not receive particular interest, both because the observations seem to indicate that our universe is open (and therefore does not identify itself with a cycle among the others), and because the number of possible “cycles” has a superior limit, and therefore such phenomenology cannot be reiterated to infinity or to whatever high number one wishes. The solution of the multiple universes works in the sense of removing significance to the anthropic coincidences, not because life has occurred by chance in our universe, but because our universe would be, by chance, one among many. A similar solution is possible in the domain of quantum mechanics. Once the whole universe is understood as a quantum object, according to what its very early stage might suggest, it could be interpreted as super-positions of a multiplicity of quantum states, of which one only would be “actualized” by the observation of an intelligent observer (   QUANTUM MECHANICS, IV.3). Although from the mathematical point of view the solution of many (space-time or quantum) universes is formally correct, it comes up against two problems: the first of which is again the problem of the whole, as we called it here above; the other is the artifice to respond with a non-verifiable solution (or non-falsifiable, if you prefer) to a verified physical interrogative. In both cases we deal with solutions taken from the philosophical realm, and no longer from the experimental-scientific field. Moreover, many authors have pointed out that the solution which appeals to the many-worlds model seems to violate the “Ockham's razor”, as it would multiply the entities not strictly necessary to resolve an interrogative that could have simpler philosophical solutions.

It is not difficult to realize that the three main objections to the Anthropic Principle (perhaps, except for the first) are obliged to appeal to some a priori philosophical arguments, which operate on a level of understanding and abstraction that exceeds the domain of experimental data, that is the domain from which the Principle (at least as a question) took origin. A kind of proof of the philosophical character of the alleged solutions, comes from the pioneering article by Carter (1974), when he asserts that « If it were to turn out that strict limits could always be obtained in this way, while attempts to derive them from more fundamental mathematical structures failed, this would be able to be construed as evidence that the world ensemble philosophy should be taken seriously — even if one did not like it» (Carter, 1974, p. 298). It is not surprising, then, that also solutions other than Carter's to the problem raised by the Anthropic Principle are almost always addressed on a philosophical, no longer on an experimental level, as, for instance, that reported by John Leslie: «the fine tuning is evidence, genuine evidence, of the following fact: that God is real, and/or there are many and varied universes» (Leslie, 1989, p. 198).

Again, it is a philosophical perspective that which presents the SAP as an expression of the evolutionary process caused by one general law, immanent within the cosmos, whose final consequence would be to generate intelligent life so that the universe “would finally become conscious of itself”. Instead, one could object that what intelligent life reflects upon, as a personal subject flourished in the universe, is much more profound than the simple “giving a voice” to cosmic evolution. As it has been rightly observed by Muratore, «the fundamental recognition that must be assigned to the human mind, is not that of a cosmos which demonstrates its intelligibility to itself, but rather the recognition of a contingent personal intelligence existing within a contingent universe. The condition of possibility of such recognition is that human beings open up a horizon of absolute transcendence which results in the recognition of their own being a creature and of that of the whole physical universe. It is nothing but to refer this contingent existence to a primary reality that is truly “other”, a reality which provides all absolute foundation» (Muratore, 1993, pp. 159-160). Opposite to this perspective there is the idealist position only, that of conceiving a completely self-referential universe.

3. The True Scientific Significance of the Anthropic Principle. It would be nevertheless erroneous to believe that the difficulty in separating the scientific data from their philosophical interpretations would deprive the suggestions brought about from the Anthropic Principle from any scientific value. I guess that such value could better emerge when abandoning of the denomination of “principle” (a name that would be more adequate in a philosophical realm), and limiting us to simply offer the set of the physical-chemical conditions originally at the basis of the “weak” formulation. To call the WAP a “principle” appears ambiguous, and it precludes the reception of the scientific results involved therein. In reality, the WAP points to a series of facts, which do not depend upon the assumption of a particular philosophical perspective, just as the charge of the electron or of the mass of the proton do not. Instead of being classified under the form of an “Anthropic Principle” that specific set of observations could be more correctly presented by the name of “biotic conditions”. The WAP is extraneous both to a deterministic bond with life (in fact it deals with necessary and not sufficient conditions; cf. above, n. 1) and to any allusion to intelligent observers. Once they are presented in this way, such biotic conditions are evidence for a significant, non-tautological knowledge with regard to the universe and its cosmic evolution. I try to recapitulate what are, in my opinion, the three more significant and relevant contents of such knowledge.

In the first place, the evolution of the universe manifests itself with a strong character of unity. The four fundamental laws of interaction and their adimensional constants determine the physics of the universe and its evolution in time, much more than all the individual events that will accompany its development after the Big Bang . The universe is certainly not a deterministic machine, as it was believed in the 18th and 19th centuries. Contemporary physics has widely acquainted us with the mathematical unpredictability of a good part of its phenomena and about the strong limits of methodological  reductionism, especially with respect to the approach to complex phenomena in the field of  chemistry, and above all in that of  biology. On the other hand, the universe does not present itself either as a whole of disconnected parts, extraneous to a unifying rationality, nor remnants of a reality whose capacity for emergence and autopoiesis would be entrusted only to chance interactions that will drive fortuitously its history. The scientific data at the basis of the “biotic conditions” (as they are derivable from the Weak Anthropic Principle) show instead that the essential characteristics of the physics of the universe are conceptually determined, and that the creativity that accompanies the morphological novelties of complexity, even remaining open and mathematically unpredictable, results implicitly conditioned by a number of basic and grounded properties that are never contradicted. These fundamental properties originate temporally within the primeval phenomenology that involved the formation of the space-time continuum, the radiation field, and finally matter, the adronic as well as the leptonic component.

Secondly, biology and human life strongly depend upon the whole history of the universe (I here employ the word “history” by analogy with the free human realm, in a somewhat inappropriate sense). In this history nothing seems to be superfluous. The very long times that separate us from the Big Bang , without which the stars would not have had the possibility to synthesize, and then release into space, the chemical elements indispensable to form organic molecules, have been necessary in order for us to be “here” and “now”. By consequence, also the dimensions of the universe and the enormous quantity of matter that it contains appear in certain ways indispensable for the presence of life, also in the case that this would spring up only on the planet Earth (   EXTRATERRESTRIAL LIFE). The radius of the universe is in fact proportional to the time of expansion, and all the quantity of matter that it contains depends upon the delicate equilibriums of the constants of nature (it could have contained much more, were not most of it transformed into radiation in the initial cosmological phases). Therefore, there is nothing superfluous, in the cosmos, but only that which is strictly necessary for hosting life.

In third place, the conditions (necessary but not sufficient) that render life possible present themselves as “original or primeval conditions”. In order for the appearance of life, the influence that a certain number of more or less casual events have had in the formation, for example, of our terrestrial habitat , has been after all inferior to the power implicitly contained in the conditions associated with the Big Bang , by means of the “fixing” of the values of the constants of nature and of the other fundamental physical constants. What I want to emphasize is not the necessity of a particular choice of those values — that would unnecessarily change the level of the argumentation from efficient causality, proper to the analysis of science, to that of a finalistic intentionality— but rather their original and non-evolutionary character. This result is enough, by alone, to frame the issue of the origin of life and of the appearance of intelligent life, in a way very different from the picture commonly assumed by many scientific circles, especially in science popularization, until our days (   BIOLOGY, V; CHEMISTRY, V). Regarding a comparison with biological evolution, the “biotic conditions” suggest that the paradigm of natural selection and the capacity for adaptation to the environment cannot be the only criteria to have operated in the long chain of events that accompanied the evolution of life.

These are the observations that seem to stand out, independent from any particular philosophical or hermeneutic paradigms. Starting from the original intuitions suggested by the Anthropic Principle, the natural sciences submit these observations as matter of reflection not only to philosophy, but also to religion.

IV. The Anthropic Principle between Science and Religion: is there any Design in the Cosmos?

After the date of publication of Barrow and Tipler's book The Anthropic Cosmological Principle (1986), there has been a notable increasing in the interdisciplinary literature on this topic. Also Catholic theology has registered a moderate but significant interest (cf. Muratore, 1992 and 1993). In the decade of the 1990, nearly all the books of science popularization which tackled the themes of the origin and evolution of the universe devoted at least one specific chapter to the Anthropic Principle. Implicit references to the Principle are also present in the recent debate regarding the so-called “Argument from design”, or other holistic approaches to  nature, that a few biologists seem today to prefer to better understand the morphogenesis of the living beings. A possible correlation between some suggestions coming from the Anthropic Principle and the philosophical thought of  Teilhard de Chardin also contributes today to keep this theme alive among scholars interested in the science-religion relationship. Because of the cosmological and biological contexts of the data that have brought about the formulation of the Principle, and because of the explanatory power it seems to possess, it is comprehensible that not a few authors have put the Anthropic Principle at the center of a debate in favor of or against the existence of a purpose in nature. The question about purpose easily shifts towards a question about the existence of an intelligent cause, and therefore of a Creator.

1. Anthropic Principle and “Argument from Design”. The idea to recognize the presence of an intelligent design in nature as a proof for the existence of a Creator, has accompanied human thought for many centuries. This theme has known a complex historical path, due to the diversity of the epistemological context — scientific or philosophical — where it has been proposed, and because of the wide meanings that the term “design” (or other terms related to it), may assume or imply, including teleology, finality, rationality, intelligence, etc. In this article I face only some of the aspects that are linked to the theme of finalism in nature: the reader can find more information in other entries of this Encyclopedia (   GOD, II; FINALITY, V-VI; UNIVERSE, IV), or in works that provide a thorough historical perspective of the theme (cf. Ward, 1961; Hulburtt, 1965; Craig, 1990; Barrow and Tipler, 1986, ch. 2; Harris, 1991, ch. 12).

Traditionally developed in philosophical contexts, as for example in the well known “fifth way” of  Thomas Aquinas that uses metaphysical arguments to ascend up to God starting from the recognition of finality in nature (   GOD, I), the “argument from design” has been first linked to “scientific” observations in the English Anglican apologetics of the 17th and 18th centuries. This movement coined the expression “physical-theological proof for the existence of God”, employed for instance by William Derham in his Boyle's Lectures of 1711. This cultural and philosophical movement had a certain development above all in the field of biology, where the physico-theologians pointed out the remarkable organization among the functions and processes of living beings, and the unusual singular harmony existing between living beings, human beings included, and the habitat they live in. In the domain of the natural sciences, the break will arrive with  Darwin, who proposed a way, until then unknown, to achieve such observed concord between living beings and their habitat resorting to natural selection and to progressive adaptation to the environment. In the philosophical domain, the argument from finality underwent a deep criticism in the Modern Age, first with  Hume, and immediately after, in a more severe way, by the thought of Kant.

The double realm, philosophical and scientific, where the argument from design is debated and claimed to be grounded, asks for some clarification. If an exclusively scientific foundation may be removed, within a scientific context, explaining the coordination and the apparent finalism by means of the action of some observed efficient causes (being the efficient, not the final causality, the proper object of science), the validity of a philosophical foundation of the argument, on the contrary, cannot be removed by new results of science, because it depends upon the correctness of the inference properly developed within a philosophical context. In other words, an argumentation developed at the level of efficient causality cannot remove philosophical inferences made at the level of ontological causality (the problem of contingency) or of final causality (   AUTONOMY, IV.1; METAPHYSICS, IV.2). For such reasons, a demonstration for or against the presence of a Design in nature, that utilizes only scientific data, can never be apodictic, simply because science cannot have a complete comprehension “of the whole”, nor can it give reason for the existence of some intentionality acting above the level of observational data. Although “finalistic” principles exist in science and they operate in mathematics, in physics or in biology, having also a certain predicting value and favoring the understanding of some particular phenomenology (  MECHANICS, VI; BIOLOGY, IV; FINALITY, II), they are nothing more than a kind of “finalistic strategy”, which corresponds to forms of teleology that can be recognized on a local scale, and that only a philosophical perspective is able to extend onto a cosmic scale. For this reason, the Anthropic Principle, or the “biotic conditions” associated with it, only indicate the coherence, the co-ordination and the interrelations existing in the structure and in the evolution of the cosmos: one cannot employ the Principle, in a straight way and without any further reflections, as the proof of an intelligent Design, nor can it demonstrate the existence of a necessary and absolute teleology towards the appearance of life and human beings. It is not without interest that researchers such as Michael Behe and William Dembski, support the legitimacy of approaching the world of the living beings under the perspective of an Intelligent design , but without necessarily endorsing any of kind of natural theology, since design is affirmed only as a cognitive strategy (cf. Dembski, 1998, 1999; Behe et al., 2000).

Another clarification regards the semantic width and the non-univocal meaning of the term design. Within the notion of “design” are contained at least three different ideas, although connected among themselves: i) the existence of regularities or patterns that are thought to be non-casual; ii) the presence of a teleology understood as mere functional or organismic finalism; and, finally, iii) the idea of finality in the strong sense, as something which refers to the presence of intentionality and intelligence (cf. Harris, 1991, pp. 162-163). Any criticism addressed to only one of those levels, very often ends up by rejecting and disapproving also the other two.However, this comes from (and generates) a kind of confusion, since we have to remind the general rule of any teleological approach: the removal of a supposed scientific cause, when substituted by other scientific causes, cannot directly imply the removal of an ontological or metaphysical causality.

2. The Peculiarity of the Anthropic Principle among the Various Arguments from Design. The Anthropic Principle seems to possess a kind of “specificity” within the more general problem regarding the “Argument from design”. Its peculiarity is the consequence of the cosmological and global context in which the Principle is raised, and that deserves to be carefully considered. Different from other forms of order, organization or regularity that we observe in nature, the biotic conditions expressed by the WAP cannot be removed employing a mechanism similar to that by which Darwinism has removed, at least to some extent, the teleological interpretation of the harmony and agreement between the different biological forms and their habitat (   EVOLUTION, III). The fine tuning of the constants of nature is not the result of an adaptation to the environment or of natural selection (at least if a unique universe is assumed), because it regards instead “congenital” conditions. The only way to remove the significance of fine tuning is to postulate either a cosmological and omni-comprehensive general law by which those conditions or coincidences may be deduced, or, also, the existence of infinite universes. Both requests have already been recognized as a priori philosophical requests, that cannot be demonstrated on the basis of experimental observations only (see above, III.2). Moreover, the teleological indications suggested by the Anthropic Principle no longer regard a teleology confined to one or more parts of the natural world, as it happened, for instance, in the 18th century argumentation on the functioning of the human eye, in the later discussion about the delicate equilibrium of the terrestrial atmospheric conditions for the sustenance of life or, more recently, when emphasizing the surprising informational complexity of molecular DNA. For the first time we are now in front of a global and all-encompassing teleological proposal, that is intended to show the functioning of a finalistic principle from the era of Planck (10^-33 sec from the Big Bang ) up until our days.

In my opinion, it is precisely this specific peculiarity of the Principle what makes it really interesting. The Anthropic Principle, in fact, is able to join together the three components of the Design: coherence, teleologism, and reference to a mind. It could not be otherwise, when embarking on the undertaking — impossible for science, yet inevitable for the scientist — to make one concept of everything, from its origins until the present, using the ideal, comprehensive frame, that contemporary cosmology is today able to provide. In the origins, “coherence” becomes “project”. In so doing, we grasp (and perhaps recover) an important aspect of finality which is less evident. It is that finality does not only indicate the physical or temporal “end” towards which a process tends, but it also indicates the coherence of the entire process as a whole. As the ends for an athlete are not only to arrive at the finishing-line, but also to achieve this in the shortest time possible, and the ends for a musical composition are not only to arrive at the last note, but to grasp the whole symphony, so the possible functioning of an Anthropic Principle would remind us that the finality of the cosmos must lay, and be recognizable, within every moment of its existence (cf. Harris, 1991, p. 168).

When the three dimensions of finality are joined together, the whole argumentation moves from the scientific onto the philosophical terrain and the Design flows within the thesis of the SAP. It must be underlined that the argument for Design possibly associated to the SAP does not necessarily possess a theist value, but, rather, it simply points to a “mind”. We realize this also by reading the many reflections of scientists who take on the onus to travel along the path of the Anthropic Principle trying to keep themselves as faithful as possible to the observational data. Freeman Dyson's comment is sufficiently eloquent: «I conclude from the existence of these accidents of physics and astronomy that the universe is an unexpectedly hospitable place for living creatures to make their home in. Being a scientist, trained in the habits of thought and language of the twentieth century rather than the eighteenth, I do not claim that the architecture of the universe proves the existence of God. I claim only that the architecture of the universe is consistent with the hypothesis that mind plays an essential role in its functioning» (Dyson, 1979, p. 251). A further conceptual step would be to judge whether this philosophical position is truly coherent. It is the assertion of those scientists who speak of a mind that is recognized to be the owner of the “project” of the universe, without being recognized as something distinct from the universe itself and, therefore, immanent to it (   LAWS OF NATURE, III.4; PANTHEISM, III.2). This it is enough to clarify that such a reference to a cosmic mind does not necessarily point to the Christian Logos, although, when opportune clarification is made and more precise conditions are specified, it is certainly compatible with it.

3. Anthropic Principle and Christian Theology of Creation. For Judaeo-Christian Revelation the whole universe, with all the richness of its phenomenology and forms, expresses a unique project of God that comes into being with the  creation. The Christian universe is the intentional effect of a personal Word, intelligible and open to dialogue. It develops through time, not because driven by a blind chance, but according to a rationality which stems from an original simplicity, that has in God its first and its final causality. Life originated as fruit of His creative will, aimed at developing towards the appearance of intelligent life at its apex. The human person enjoys a special dignity, being created in the image and likeness of God, and having therefore the capacity to recognize the Creator through His works. The greatest dignity of the created world is shown by the Incarnation of the Son of God, because a human, created nature, is taken up by God, in the Word made flesh (   JESUS CHRIST, INCARNATION AND DOCTRINE OF LOGOS, II).

The relationship between humankind and the created world is summarized in a passage from Gaudium et spes : «Through his bodily composition man gathers to himself the elements of the material world; thus they reach their crown through him, and through him raise their voice in free praise of the Creator» ( Gaudium et spes , 14). It is easy to note that this theological perspective is certainly in agreement not only with the scientific data that points out the existence of a certain number of biotic conditions, but also with those philosophical formulations that offer a possible finalistic reading of the Anthropic Principle. However, two clarifications are here needed. Theology warns that such a finalism must be able to refer to a source of rationality, to a Logos , that does not identify itself with the same universe, but transcends it. That humankind realizes to be the voice of all creatures, and these find in the human being the crowning and the awareness of their long evolutionary history, is a sign of human freedom, not the result of a blind necessity. At the same time, the agreement between these two perspectives, theological and scientific, does not constitute any “scientific demonstration” of the existence of a personal Creator. We can speak only of a simple consonance : the biotic conditions expressed by the Anthropic Principle are consistent with that which the theology of creation says, but no logical-demonstrative proof of any theological content is asked, nor entrusted, to the knowledge brought about by the Principle. Let us look at the reasons for that.

If the universe has a first transcendental Cause, that determines all the cosmic fundamental characteristics and features, and drives the physical-chemical evolution as a final Cause does, then the analysis of science would reveal just what it actually observes: a cosmos with steady and intelligible properties; the capability the universe has to be unified by a certain rationality be recognized as the effect of a unique cause; the presence of conditions necessary to host life; times of physical and biological development long enough to allow cosmic evolution, and thus life. Nevertheless, the reverse inference does not stand: that is, the observation of all these delicate conditions, necessary but not sufficient for the development of life, does not reveal on its own, and with scientific methods only, the existence of a Creator. What on the philosophical and metaphysical level has the character of an intentional finality, and on the theological level reveals itself as source of meaning and having the character of a gift, on the level of mere empirical analysis can be only seen as physical and mathematical coherence.

Such a necessary distinction does not mean that a scientist cannot use the evidence of this coherence as support for the credibility of his or her  faith in God Creator. It only means that to judge things in this way requires a further philosophical abstraction, above the empirical data, and it probably implies the decision to put the presumed evidence for Design in relation with other motives to believe in God, already owned by the subject. This is why, starting from the same data, there are scientists who arrive only at inferring the existence of a “cosmic mind”, an immanent intelligence with which only mathematics, not the human person, can actually dialogue. Philosophy and theology indicate this total identity between God and the world by the name of  pantheism.

Thanks to the above distinction between the scientific and the philosophical levels, the objections that deny any scientific significance to the data associated with the Anthropic Principle (see above, III.2), do not constitute, by their own, any “scientific” refutation of the existence of a Creator. As I have noticed before, such objections are philosophical, not empirical, and they are not exempt from a priori assumptions, more or less declared. In particular, the recourse to a multiplicity of universes, invoked to justify the existence of anthropic conditions for our universe, does not imply that the appearance of humankind must be considered a casual epiphenomenon lacking of any purposiveness. This last conclusion cannot be strictly supported by science, since all these universes belong to “unconnected” space-time regions that would not be the object of physics, nor of a consistent statistics grounded upon the experimental method. Neither would the role of a Creator be denied from a philosophical point of view, since nothing forbids multiple universes, in one of which life flourished, to all belong to the same creative project. To support a many-worlds model as a unique, possible justification for the biological suitability of our universe, rather manifests the defense of a philosophy that maintains, at any cost, a casual interpretation of life, that is its non-purposeful appearance. On the other hand, to consider the appearance of life and then humankind as the inevitable result, within a unique universe, of an immanent evolution that denies a transcendent, divine projectuality, is also an a priori philosophical conclusion, since there is no scientific evidence that the necessary conditions to host life in the universe are also sufficient conditions for the appearance of intelligent life.

Summing up, I would suggest that the major relevance of the Anthropic Principle in the terrain of dialogue between science and religion resides in the fact that it furnishes the researcher with elements of reflection on the ultimate whys of reality, and on the “mystery of being”. Taking the cue from scientific observations, the researcher wonders again about the role of humankind in the cosmos, with a questioning capable to involve him or her at the existential and even religious level. Science is not new to the possibility for provoking “ultimate” questions from inside, that is within its research activity, although it perceives its inadequacy to answer these questions exhaustively by means of empirical tools only (   MYSTERY, IV). The elements of reflection offered by the Anthropic Principle appear, from this point of view, among the most stimulating for the comprehensiveness of the context in which they emerge, which is no longer the context of one or another discipline, but that of physical cosmology, stretched in its desire to make the whole universe a unique object of intelligibility.

V. Anthropic Principle and Theological Christocentrism

1. Unity and Coherence of the Cosmos under a Christocentric Perspective. A central aspect of the Christian theology of creation is to indicate the Incarnation of the Son of God, and more precisely the design of God-Father to recapitulate and reconcile all things in Christ, as the most important principle of coherence and unity of all that is created. Such a headship of the Incarnate Word does not act in virtue of the Incarnation alone, but because of the whole paschal mystery of Jesus Christ, dead and risen (   MYSTERY, II.2). The glory of the risen Christ is therefore presented by the Sacred Scripture as the completion of the expectation of the whole created world, as the beginning of a new creation. Based on the Christological Pauline hymns (cf. Eph 1,3-10; Col 1,15-20) and on the Johannine doctrine of the mediation of the Word in the creation (cf. Jn 1,1-4; cf. also Heb 1,2-3), theology has expressed in various ways the headship of the risen Christ, reading again, in a new Christological context, that anthropological headship possessed by the human being, as it is presented in the book of Genesis . Here, within the panorama of all the creation, the human being stands as the apex of an ascending path, that starting from simpler living forms raise up to the appearance of homo sapiens . The position of Christ in the creation reveals and redeems the position of the first Adam within the plan of God. This theological perspective can be found in authors belonging to different historical epochs, from the Fathers of Church up until our time, and it is usually indicated by the name of “Christocentrism”. We could then ask whether the centrality of life and the special role of intelligent observers, as they are stated by the Anthropic Principle, might contain some points of connection with a theological anthropology finding its completion in a Christocentric perspective. We note here that the reverse question, that is whether a Christocentric theological perspective can serve to shed light on the coherence, rationality, and significance of a created universe, object of study of the natural sciences, has been replied to in another article of this Encyclopedia (   JESUS CHRIST, INCARNATION AND DOCTRINE OF LOGOS, III).

The fact that, when speaking of Jesus Christ, the Scripture affirms that «all things were created through him and for him», and moreover that «He is before all things, and in him all things hold together» ( Col 1,16-17) had already brought Duns Scotus (1265 ca.-1308) to suggest that Christ, the Incarnate Word, was the first of the predestined, and therefore He was the true end God had in mind while creating the universe. This medieval Master does not consider the Incarnation as the crowning of creation (elevating purpose), that together with the redemption of humanity (healing purpose) would constitute the two scopes of the creative will of God. Scotus tried to overcome the impasse , proper to its epoch, of having to choose or confront between these “two ends of the Incarnation”. He affirms, instead, that the Incarnation of the Word is rather the grounding reason for the creation itself: God would not have wanted Christ for the universe, but the universe for Christ . The Christocentric perspective of Scotus has undoubtedly the merit to place again the accent on the relationship between Christ and the creation, but it had the limiting factor to place the Incarnation “as such” at the center of the divine design, not the paschal mystery of the risen Christ. In reality, a more equilibrated vision would place the latter at the center of God's plan, as it results for instance considering the Book of Revelation , which presents the immolated Lamb having the characters of the Alpha and the Omega (cf. Rv 1,8; 21,6; 22,13), the eternal mediator who works both in the principle and in the end.

The association of the mystery of Christ, center and fulfilment of creation, with an Omega point towards which the history of the cosmos would tend, has been proposed by Pierre Teilhard de Chardin (1881-1955). The French author reads the biological and cosmological evolution — of matter to life, of life to man, and of man to Christ — as a grandiose ascending process that realizes the definitive headship of Christ over all things: «instead of the vague focus of convergence which recalls the end of this evolution, we see now the personal and definite reality of the Incarnate Word, in which everything assumes consistency, that manifests and installs itself. Life for Man. Man for Christ. Christ for God» ( L'avenir de l'homme , 1959, posthumous). It is not surprising, therefore, that the work of Teilhard is implicitly (and sometimes explicitly) present in numerous presentations of the Anthropic Principle, especially those made by scientists who are believers (cf. Coyne et al., 1987). Probably it has also inspired the reflections of Barrow and Tipler (1986) on the final destiny of the universe (cf. ch. 10), so giving origin to the formulation of a Final Anthropic Principle (FAP). This latter formulation, however, is much less convincing and seems to endorse a reductionist vision of life and humanity, since it will the  information, according to their view, to inherit the final destiny of being eternally present in the cosmos. In the following years, Barrow has no more proceeded along this line of thought, while Tipler has developed it in a way that is even less convincing, philosophically fantastical, and clumsy (cf. Tipler, The Physics of Immortality , 1994). In reality, as far as I know, the original thought of Teilhard de Chardin did not contain a reductionist vision of life, nor the idea of a determinist finalism that would lead the whole cosmos towards the Incarnation, with an absolute necessity, up to a point in which the universe assumes pantheistically the divine characters: «Is it not perhaps the counter-check that we were waiting to confirm the presence, on top of the world, of what we have called the Omega point? Or at least, in a more exact formula, “to confirm the presence, on top of the world, of something even more elevated, in line with the Omega point”. This respects the thesis of the “supernatural”, a thesis according to which the sketched unified contact hic et nunc between God and the world reaches a super-intimacy and so therefore a super-gratuity to which man could not think nor pretend in virtue of the only requirement of his “nature”» ( Le phénomène humain , 1938). The suggestion and grandiosity of the Teilhardian vision of a finalism aimed at reaching Christo-Omega explains the attraction that the French thinker has exercised upon many writers, who gain inspirations that are developed in scientific and literary contexts other than Christian. From his part, Teilhard had underestimated the mediation that Christ exercised “in the principle”, and did not offer, also for the not strictly theological character of his writings, a complete understanding of the relationship of continuity/discontinuity between the first and the new creation. To be adequately appraised, the consideration of such a relationship would have required, at some level, also the pondering of the mystery of human sin (for a short evaluation regarding the thought of Teilhard:  JESUS CHRIST, INCARNATION AND DOCTRINE OF LOGOS, III.2).

2. The Paradox of the Cosmos and the Mystery of the Risen Christ. Beyond the attempts of Duns Scotus and Teilhard de Chardin, what could a Christocentric theological perspective add to the dialogue between science and theology within the terrain of the Anthropic Principle? A theology of creation that would recognize the existence of a “harmony” or a “consonance” between the suggestions brought about by the Anthropic Principle and the dynamic vision of a created world that tends to the appearance of the human being (see above, IV.3), could read the “meaning” of creation according to a Christocentric, not only to an anthropocentric, perspective. On the other hand, in the same way as the Anthropic Principle could not demonstrate, on the scientific level, that the appearance of the human being fulfils an immanent and unavoidable cosmic law, so it could not demonstrate any necessity for the Incarnation of the Word. If it is true that God wants the world for Christ, it is no lesser true that this will belongs to the mystery of the Father ; it belongs to a personal intentionality that remains non-accessible to scientific data, or to any philosophical (aprioristic) use of a strong Anthropic Principle. In spite of that, when a Christocentric and not only an anthropocentric perspective is assumed, the “consonance” between theology and science could reveal unsuspected dimensions, hidden in the biblical data. The New Testament affirmation that “all things exist in Christ” and that creation was made “in view of Christ” would show once more the coherence and unity of all material reality, now summarized in the true human nature of the Incarnate Word. Suggestions for Christology might be derived too. They should be prudently evaluated, but had certainly something to gain from the widening of horizons brought about by contemporary cosmology. «Does an evolutionary perspective bring any light to bear upon theological anthropology, the meaning of the human person as imago Dei, the problem of Christology — and even upon the development of doctrine itself? What, if any, are the eschatological implications of contemporary cosmology, especially in light of the vast future of our universe?» ( Letter to the Director of the Vatican Observatory , June, 1, 1988, OR, October, 26, 1988, p. 7).

Precisely regarding this “future”, I believe that theological Christocentrism brings its specific contribution to the new vision of the cosmos produced by the Anthropic Principle. This Principle, in fact, meets up in a paradox: that of a universe that is recognized as “finely tuned” with respect to the parameters necessary for life (WAP), or even declared purposefully oriented to the appearance of intelligent observers (SAP), but a universe in which the “window of opportunity” for the sustenance for life and of human beings remains extraordinarily small. The thermodynamic evolution of the Sun will not permit the terrestrial biosphere to perennially maintain the favorable parameters of temperature, humidity, pressure, etc. that today make survival possible, but will end up by altering, in an irreversible way, the conditions necessary for life, impeding its prolongation. Although it will happen on a time-scale that is rather long when compared to the interval of time corresponding to the origin of the human species (though comparable with that corresponding to the appearance of life on the planet), it is a very short time-span when compared to the whole history of the cosmos, which is still very young, as shown by its overall chemistry. Such a situation provokes the radical interrogative on why, from its very genesis, does the universe contain the keys for an opportunity that would be destined to terminate quite soon. Would some thing serve this “evolutionary effort”, this delicate action of fragile equilibriums, if then life is destined to be extinguished on a time-scale much shorter than that of the future existence of the inanimate matter? The possibility that life has grown on planets around stars different from the Sun (  COSMOS, OBSERVATION OF THE, II), would leave the paradox unresolved. The general conditions for the stability of galaxies (stellar evolution at their interior) and of the cosmos in its entirety (cosmological expansion) limits in some ways the favorable conditions for life within narrow, well-circumscribed intervals of time.

It is from the mystery of the risen Christ, and that of his relationship with the whole creation, that such a paradox might receive some light. A universe created through Christ and in view of Christ would imply, by analogy, the same logic of death and resurrection revealed by the Incarnate Word. In a Christocentric universe, life and matter are destined to be transfigured, as the body of the risen Christ (   RESURRECTION, VI). Once it is assumed that our created universe has to reproduce the same logic of the paschal mystery, then the existence of a narrow window of opportunity for life, as the adequate conditions for its development last for a very limited time, appears no longer contradictory, even though the whole cosmos is so well regulated to favor the rise of life. This is a response that faith, not science, can offer to the paradox; but one that maintains a deep coherence with what theology affirms concerning a creation understood within a Christocentric perspective, enlightening science on what it could not say on its own. At the same time, the existence of this paradox can demonstrate the inconsistency, both on scientific and philosophic levels, of the idea that the strong Anthropic Principle is an expression of an all-encompassing and determinist super-law, governed by a mind immanent within the same cosmos. In fact, it is precisely in this case that the enormous evolutionary effort made by the cosmos would remain truly contradictory.

The extraordinary import of such interrogatives manifest that the major existential question regarding human life can be extended also to a cosmological level: why is there  death? Such a question seems to now assume a new physiognomy, able to involve the universe in its wholeness (   CREATION, VI). Scientific analysis can explain the manner with which death will happen, both on the personal and cosmic level, but is not able to free humankind from the idea that in the event of death and in the apparently unavoidable destiny of life in the cosmos, is there contained a contradiction that can be healed. And, perhaps, because of the intimate perception of such uneasiness, also the world of science can focus more attention on hearing the words of the Psalmist: «When I see your heavens, the work of your fingers, the moon and the stars that you set in place, what are humans that you are mindful of them, mere mortals that you care for them?» ( Ps 8,4-5).

Giuseppe Tanzella-Nitti

See also: COSMOLOGY; FINALITY; LAWS OF NATURE; UNIVERSE.

Bibliography

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