Religion and the Physical Sciences

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This entry is concerned with philosophical questions arising from the interaction of religion and physical science. Here the focus is primarily upon Western religious monotheism, for this is the larger religious context in which modern science arose. And among the physical sciences, the focus is on astronomy and physics.

Historical Roots

The relationships between physical science and monotheism have deep roots in the history of Western thought. The simple assumption that religion and science have been and remain in conflict is falsified by the historical data. Rather, more complex and interesting connections hold between religious faith and scientific understanding in at least three domains: individual scientists and scholars, social institutions, and worldviews. At the individual level, the facts are too complex for one simple view to be true all the time, or even in a majority of cases. At the institutional level, the record of religion is at best one of indifference, and at worst outright opposition to physical science. At the level of worldviews, in contrast, Western religion has helped to make modern physical science possible.

The regular pattern of astronomical events traced by ancient Babylonian astrologers and the understanding of the physical world in Greek natural philosophy and astronomy gave currency to the idea that there must be a supreme god of some sort behind the universal patterns of causes and motions in heaven and earth. As Plato argued in The Laws, "If the whole path and movement of heaven and all its contents are of like nature with the motion, revolution, and calculations of wisdom, and proceed after that kind, plainly we must say that it is the supremely good soul that takes forethought for the universe and guides it along that path" (bk. 10, 897c). Both Plato and Aristotle were philosophical monotheists, a view based in part on their understanding of the workings of nature.

The tradition of Greek natural philosophy continued to develop in the monotheistic traditions of Christian, Jewish, and Arabic scholarship by means of commentaries on the physical works of Aristotle. What these philosophers had in common was what we might call a macrodesign scientific worldview: God created the whole cosmos and sustains the principles and laws of nature that regulate physical interaction and motion. The purpose of natural philosophy (as physical science was then called) was to investigate the primary and secondary causes sustained by the first cause. Natural philosophy did not discuss God per se as the first cause, nor did it appeal to God as an explanation for the natural phenomena of the world. God's nature was the province of theology. This division of labor aided the development of the rationality of early modern science in the European universities in the thirteenth century, the later Middle Ages, and the Renaissance.

Important to this development was the influx of the "new" Aristotelian science from Arabic sources. Combined with a Platonic-Pythagorean tradition of mathematics, this Aristotelian tradition of empirical study was assisted by voluntarism in theology and nominalism in metaphysics. This complex tradition of inquiry formed the background to the development of early modern science and made sense of a quest for empirical, mathematical laws of nature grounded in the will of the Creator. A good historical example of this combination is Jean Buridan (c. 12921358), a natural philosopher and one of the most honored intellectuals in Europe, who was twice elected rector of the University of Paris. In his commentary on Aristotle's On the Heavens, he wrote, "In natural philosophy we ought to accept actions and dependencies as if they always proceed in a natural way" (bk. 2, ques. 9; p. 423 f.). In the same question, Buridan went on to attribute the existence and design of the universe to God as first cause, but he did not appeal to God in natural philosophy.

The scientific revolution was a genuine revolution in human thought. Despite some continuity with the Middle Ages, a whole new way of seeing the world was born. The contributions of Nicolaus Copernicus, Galileo Galilei, Johannes Kepler, and Isaac Newton, for example, gave rise to a new understanding of the physical cosmos. While a macrodesign worldview did assist in the development of early modern science, there was tension at the institutional level. The Catholic Church continued to insist upon its right to judge theological truth, including the proper way to interpret the Scriptures. The Catholic astronomer Galileo Galilei (15641642) ran into trouble with the Congregation of the Holy Office (the Inquisition) over exactly this point. In his famous "Letter to the Grand Duchess Christina" (1615/1957), he argued as an individual scholar that the Scriptures should be interpreted in a manner consistent with the new Copernican astronomy. The Counter-Reformation authorities in Rome soon banned the work of Copernicus "until corrected," and got Galileo to agree not to publish his views except as purely hypothetical theories. When Galileo broke this agreement by publishing his Dialogue concerning the Two Chief World Systems, he was suspected of heresy and forced to recant publicly. This became the most famous example of institutional religion suppressing the scientific quest for truth in the physical sciences.

For the most part the Christian churches have been unconcerned with science, focusing instead on spiritual truth and religious practices. Indeed, by creating the Western university and the hospital, the Church provided indirect support for scientific research.


By way of contemporary issues of philosophical interest, the rise in the latter half of the twentieth century of theology-and-science debates has stimulated a number of methodological questions concerning both religion and science. The question of how we know in both disciplines has given rise to philosophical investigation into the nature and limits of knowledge in physical science and academic theology. Thomas Kuhn's Structure of Scientific Revolutions (1962), a revolutionary work in the philosophy of science, made a lasting contribution to the dialogue between theology and science. Science, according to Kuhn, is based on tradition and on "paradigms" of shared values, rationalities, and perspectives that gave shape to each of the scientific disciplines. It is thus based on epistemic values and metaphysical presuppositions that it owns but cannot justify. Far from being a complete worldview, science depends upon these larger perspectives for its working assumptions. This overarching view brought science into closer contact with philosophy and religion, since it was no longer the domain of purely objective, empirical fact derived from logic and evidence alone.

Investigations of the different methods of theology and science has also raised issues in the philosophy of language. How language is used in both physical science and theology has highlighted the importance of analogy and metaphor for both disciplines (Barbour 1974). This is especially true in subjects that study phenomena beyond human experience or full comprehension, for example, God and quantum reality. Yet both theology and quantum physics wish to make truth claims about their subjects, and this can only happen if we allow metaphorical truth and analogical predication.

Mathematical Perspicuity

Contemporary physical science, going back to the days of Galileo, constantly uses mathematics to model reality. Yet mathematics is a symbolic language that humans created over centuries but never grounded in pure logic. Why should mathematics be such a powerful tool to describe physical reality? The physicist Eugene Wigner raised this question in his oft cited essay "The Unreasonable Effectiveness of Mathematics in the Natural Sciences" (1960). The structures of mathematics and the deep structure of the physical universe share a feature that makes physics possible. Especially in the area of quantum physics, the ability of mathematics to predict the outcome of difficult and complex experiments is a striking example of this aspect of the universe. For theoretical physicists, the beauty and elegance of the mathematical formulas of a theory has become a key indication of the truth of the theory. But why should this be so? Is there any a priori reason to believe that the structures of mathematics should describe and predict the nature of the cosmos so well? Religious faith, especially monotheism, provides an answer to this question. The rational mind that designed the cosmos set it on a mathematically well behaved path (macrodesign again). Whether this is the answer to the question is a matter of serious dispute. A possible naturalistic answer might point to the evolution of the brain. Human consciousness (including the ability to create mathematics) is the ultimate product of the very laws and principles of nature that we studya fact that makes their harmony seem more reasonable, perhaps.

Astronomy and Cosmology

From mathematics we now turn to astronomy. Three areas of this science have especially drawn the attention of philosophers and theologians: the age and size of the universe, big-bang cosmology, and the fine tuning of certain physical constants in a way that allows for the evolution of stars, planets, and people. This discussion requires the distinction between a universe and the cosmos. Here "universe" refers to our space-time domain. A universe is a spatially related collection of objects under a set of natural laws and principles. "Cosmos" refers to all the universes that have ever been or ever will be.

Our universe is expanding, and this implies that it had a beginning, when the volume of space was zero and physical time first began. Along with this discovery, astronomers in the twentieth century discovered how vast the universe really is. We are a very small part of a gigantic system of planets, stars, galaxies, and galactic clusters whose vast reaches boggle the mind. Just our galaxy alone consists of 100 million stars, and many of them may well have planets. How can we think of the Earth or our species as special in any way? Philosophers and scientists alike have embraced a kind of Stoic defiance against a cold, dark, empty universe in which humanity has no special place. Somehow the vastness of space and time makes humans less significant, they argue. However, this ignores the fact that the God of traditional Western religion is both eternal and omnipresent. To an infinite, unbounded deity, what difference can it make how big or old the cosmos is? Any finite being will be the same relative to the creator, namely, of limited time and size. In biblical religion, the special status of human beings comes from their capacity for a personal relationship with God, not from how big, strong, or old they are. Still, the scientific conception of our universe has forced religious scholars to rethink the interpretation of the Scriptures and their understandings of the place of humans within creation. But nothing in the size and age of the universe actually falsifies the teachings of the great world religions.

The development of the concept of an initial singularity for the entire universe is one of the fascinating stories of twentieth-century physics. Suffice it to say that reluctantly, after several decades of debate, the physics community agreed that the general structure of space-time is dynamic. While such a conception of the beginning of the universe fits very poorly with the scientific materialism common in the physics community of the twentieth century, it does fit quite well with the older macrodesign view. The problem has to do with what caused the cosmos to come into existence. Even if space and time break down at the very earliest moments of space-time, we can still point to the first instances of time (which would not have any particular metric) and ask, Where did that come from? What caused it to be? Where do the structures and laws that allow such an event to take place come from? A macrodesign worldview has an answer to these questionsnot a scientific one, but a religious one. The cosmos has a creator of some kind, who must be eternal, omnipotent, and omniscient (in fact, a necessary being). Note that this answer is not physical but metaphysical. It has implications for religion as well.

Philosophers who resist this implication, such as Quentin Smith and Adolf Grünbaum (2000), are forced to suggest either that (1) the earliest prematerial phase of the first quantum field that gave rise to the big bang sprang into being from nothing at all, or that (2) we can only ask questions about things that begin to exist when there is a space-time metric to measure temporality (Grünbaum), or that (3) the cosmos was just an accidental, random event in an infinite series of random events. None of these answers is especially cogent. First, a quantum field is, after all, a kind of order. Where did this order come from? If matter is structured energy, as quantum theory teaches, the origin of structure is the key to the question of where matter comes from. The idea that all matter sprang out of an utter nothing at allnot simply no particles, but no laws, no fields, no energies of any kindseems rather absurd. Second, to suggest that we can only think about why things come into being when there is a temporal metric to the time in question confuses physics and metaphysics. In metaphysics, it is still perfectly natural and rational to ask where the universe and its measurable temporal passage came from (and where it came from in the first place), even if there was no physical, measurable time prior to the first event of cosmic time. Finally, to suggest that the whole cosmos is purely random seems much more like an evasion of the problem than an attempt to answer the question. To postulate an infinite number of universes (or space-time domains) only to explain the design of this one is ad hoc and violates in the most extreme way Ockham's razor, or the principle of simplicity. We should not need to be reminded that this principle is important to the rationality of both physics and metaphysics. The existence and ultimate origin of the cosmos cry out for an explanation. This final issue, however, raises the question of design, and the possibility of a "multiverse," in the fundamental structures of physical reality.

Fine Tuning, Design Arguments, and the Multiverse Hypothesis

In addition to the cosmological argument (the existence of the universe as evidence for the existence of God), in the 1990s there appeared a new and powerful version of the design argument that relies on certain fundamental constants in nature. It seems that for any intelligent life (including human life) to ever evolve anywhere in the universe, the exact values of some fundamental physical constants must be so precisely fine-tuned and balanced that it boggles the human imagination. For this reason John Barrow and Frank Tipler have called these physical constants "anthropic."

This quality of fine-tuning for anthropic purposes is widespread. Stephen Hawking, for example, estimates that the initial temperature of the universe at 1043 second was fine-tuned to one part in a trillion. A tiny increase would have precluded galaxies from condensing out of the expanding matter; a tiny decrease would have resulted in the collapse of the universe. Such fine-tuning is also present in two constants in Einstein's equations for general relativity: the gravitational constant and the cosmological constant. It is also found in the fine-structure constant (which regulates electromagnetic interaction), the proton-to-neutron mass ratio, the weak nuclear force, the strong force, and so forth. According to Barrow and Tippler, a 50 percent decrease in the strength of the strong force, to take another example, would make all elements necessary for life unstable.

The initial response to this problem was to develop a number of inflationary models of the big bang. According to such models (and there are many of them), matter in the very early universe (1035 second) expanded faster than the speed of light but then slowed down, and this resulted in a nearly flat curvature of space and the isolation of our relatively homogeneous space-time within a larger cosmos. We should remember that these models are highly speculative and as yet have no empirical support (that is, they are mathematical and theoretical constructions). On the basis of some inflationary models, theoretical physicists have gone even father and suggested that our cosmos may be a "multiverse." In such theories, which need much further investigation in both physics and metaphysics, our universe is one space-time domain in a vast cosmos that might contain a large number of other universes. No serious astronomer or physicist suggests that there are an infinite number of universes. But there could be an extremely large number of universes in the cosmos, and the number might be potentially infinite (that is, finite at any moment of time but open to an infinite future). If we assign laws and principles of nature randomly among all these universes in the cosmos, the fact that ours is so well fine-tuned for the evolution of intelligent life seems less surprising.

But is it less surprising? Stephen Barr (2003) has argued cogently that even if there are many, many universes in the cosmos, the fine-tuning needed across the whole range of principles and laws is so great that no finite number of universes would lower the "surprise" (the probability of our universe, against a background knowledge consisting only of the truths of reason). If Barr is even close to being right, then the multiverse hypothesis does very little to make our biologically friendly universe less surprising (or more probable). Perhaps some macrodesign scientific worldview is the most rational explanation of the order of the universe. Other options are possible, of course, for those uncomfortable with belief in some kind of creator. These options include the view that epistemic probabilities are purely subjective, and that the only real probabilities are physical ones, so that one simply cannot judge probabilities for the initial conditions of a universe. Another possibility is that our probability reasoning cannot apply to a whole universe: Any universe is just as improbable (and just as probable) as the next one. We are extremely lucky that one universe in the cosmos of multiple space-time domains is capable of bearing life. Despite these options, or perhaps because of them, philosophers, scientists, and theologians continue to find the new fine-tuning arguments of great interest.

See also Religion and the Biological Sciences.


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Alan G. Padgett (2005)

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Religion and the Physical Sciences