There is a long and venerable tradition of Christian reflection upon natural philosophy, or as we now call it, natural science. Since the world is God's creation, Christians who value all of God's gifts, including the natural world and their own reason, have wished to incorporate the sciences along with the best theology into a meaningful world view, at once scientific and faithful to the gospel. Origen's First Principles, written in the second century A.D., was the earliest attempt to formulate such a comprehensive Christian world view; the most impressive is doubtless the Summa of Thomas Aquinas, the Angelic Doctor, who reconciled Aristotelian science with Christian theology.

While I do not believe that science provides a true challenge to faith in the long run, there can be large areas of apparent conflict between religion and science. In fact, the historical connections between them are a fascinating study in complexity and a good antidote to the usual stereotypes. The burgeoning interest in the religion-and-science dialogue has even created a new chair in religion and science at Oxford University, which has just been filled by the historian John Brooke. Professor Brooke recently gave the prestigious Gifford Lectures with his colleague Geoffrey Cantor (another historian of science). The published version of the lectures, Reconstructing Nature, provides us with a rich array of thinkers across the centuries "whose science and theology were interrelated in interesting, unpredictable, and extraordinarily diverse ways."

Most thoughtful religious intellectuals would agree that we are faced with significant new challenges to religion from the biological sciences, at least on the face of things. After the work of Einstein, Bohr, and Hubble, the physical sciences no longer seem the threat they once did (if indeed they ever were). Since the days of Darwin, on the other hand, biology has provided a series of apparent challenges to Christian thought. Recent developments in genetics and in biotechnology have only increased the need for a new synthesis between the best science and the very best Christian theology. I believe this to be a fundamentally communal project, involving Christian scholars from many domains in fruitful dialogue and discussion. In deed, B&C has proved to be one locus in which such open and reasonable debate has taken place.

Anyone interested in a Christian approach to the philosophy of science will welcome Del Ratzsch's Science and Its Limits. A reliable and readable guide, it is the first book I would put in the hands of anyone who is new to the subject. The book first appeared some 15 years ago under the title The Philosophy of Science, and was a very useful textbook in my classes. Now updated and expanded, it should serve a new generation of readers well.

Ratzsch begins with a historical survey, including a brief new section on postmodernism. He canvasses the major issues in philosophy of science, including data and theory choice, realism and antirealism, and the limits of science. A large section is devoted to issues of religion and science, including the question of whether science poses any challenge to Christian faith. Here Ratzsch follows Alvin Plantinga and "Reformed epistemology" (no surprise from a Calvin College philosophy professor!). There is a new chapter on the intelligent design movement as well. All told, a good read at a good price.

Those who find their philosophical appetite stimulated by Ratzsch may wish to move on to a recent book from the pen of Anthony O'Hear. O'Hear is a seasoned philosopher and teacher. In Beyond Evolution: Human Nature and the Limits of Evolutionary Explanation, he writes in that wonderful British tradition of clear, thoughtful, and considered philosophy. The main purpose of this book is to swim against a current trend to reduce those great Platonic verities of truth, beauty, and goodness to biological categories. Some (though not all) sociobiologists and evolutionary epistemologists insist that our "moral" behavior, and our rationality, can be fully explained in Darwinian terms. O'Hear sets himself against this trend. He fully accepts biological evolution, but presents cogent arguments why our attraction to, and use of, truth, beauty, and goodness cannot be explained on biological grounds. Self-conscious animals, once they evolve, behave in ways which natural science cannot fully explain. While I do not accept all of his conclusions (what philosopher would?), I believe he makes a good case against any simple biological reductionism.

Both Ratzsch and O'Hear talk about the "limits" of science. And science certainly does have its limits. I prefer, however, to speak of the focus of science, especially its explanatory focus. I am unwilling to draw artificial limits to science. The methods of any science follow from the aims of that science. Natural sciences aim to understand the physical world. The true limits of science come from the very thing that has caused its huge success: a focus on physical properties and things. Some authors on both sides of the religion-science debate argue that natural science must include a "methodological naturalism." I should like to propose a bold hypothesis: there is no such thing as methodological naturalism in natural science. Rather, the term "methodological naturalism" is always and everywhere a front for full-blown philosophical naturalism. Those who defend this "mere" methodology always end up re sorting to naturalism pure and simple. And those who attack it, like William Dembski or Phillip Johnson, are in fact attacking philosophical naturalism. There just is no such thing, then, as a merely "methodological" naturalism that is limited to the actual practice of modern natural science.

My own work on the problem of induction has led me to conclude that explanation in any of the sciences comes in particular traditions and "paradigms" which are part of the history of that discipline. To learn a science is, in part, to be inducted into a way of thinking about the world. The natural sciences have been successful because they have limited their interests to the natural world. They are interested in measurable properties, mathematical relationships, models and laws that are physical or natural in their province. Their focus is on the nature, properties, powers, and relations of physical objects (including energy and living things). Natural sciences explain things based upon this background knowledge and specific focus. The natural sciences explain natural events against the background of theories about physical properties and powers.

What is called "methodological naturalism" is in fact the tradition of inquiry that dates back to medieval scientists like Robert Grosseteste and Roger Bacon. This tradition of inquiry focuses on natural explanations and natural things, which can be known through empirical (rather than logical) analysis. Natural philosophy was thus distinguished from theology because of its focus, which in turn dictated a new, empirical method, combining experimental and mathematical reasoning. Almost all of the early Western scientists, from Grosseteste to Galileo, were Christians. The idea that they were involved in the advance of "naturalism" of any kind is historically absurd. Within their proper domain, the natural sciences have been immensely successful in expanding our knowledge of creation. But this should not be confused with "naturalism." Rather, it is the focus of the natural sciences that creates both its explanatory power and its explanatory limits.

Major philosophical obstacles to naturalism (which is a kind of atheism) have long come from the tradition of natural theology. Literature regarding natural theology was common in the nineteenth century, but has fallen into decline since Darwin. However, the tradition is on the rise again, and will continue to pose some difficult conundrums for naturalism. The greatest living natural theologian is Richard Swinburne, another Oxford professor.1 Swinburne has given the argument from design a new power and elegance, based upon rigorous philosophical logic and the latest natural science. He has managed to overturn the objections of Hume and Kant, and generally rehabilitated arguments for the existence of God based upon evidence. Like O'Hear, Swinburne accepts biological evolution in the strict sense because of its evidential basis. His argument stems from the order and structure of the physical universe, which makes evolution possible in the first place. God is the author of Nature and the designer of its order and structure.

In the United States the banner of "design" has been taken up by members of the intelligent-design movement. Composed of philosophers, scientists, and at least one lawyer, this group is not content with a good argument from de sign against philosophical naturalism. They wish to insert "design" into the paradigms and explanatory traditions of the natural sciences. Among this group, William Dembski is a new and authoritative voice.

Dembski is a bright young mathematician who earned his doctorate in the mathematics of probability, then went on to a doctorate in philosophy (also with an emphasis in probability). His several works on this topic are one reason this idea has caught on. One cannot have read much of this journal without seeing his name, for example. And I believe this is a salutary development in evangelical reflection upon the natural sciences.

Advocates of intelligent design respect the natural sciences in general, and biology in particular. Most of them will accept biological evolution, as long as that is not the whole story. This is a great step forward in the religion-science debate among conservative Protestants. No longer is the theory of evolution as a whole rejected as un-Christian and un-biblical. The "young earth" hypothesis, though still a staple on the "creation science" circuit, is rejected by most members of the intelligent-design movement.

In contrast to Swinburne, whose version of the argument from design focuses on the contention that the whole of the physical universe is designed, Dembski and friends focus on the design of particular items within the physical universe. They tend to ignore the larger argument against naturalism, from the universe as a whole, although they certainly agree with this contention.

Now it is true that the difference here is a matter of emphasis, but it is nonetheless significant. The stated aims of the intelligent-design movement include scientific and philosophical challenges to "Darwinism" and naturalism.2 One might think that an argument from design to the existence of God would be celebrated, rather than ignored. But the focus of the intelligent-design folks is upon design in living systems.

Dembski presents us with two recent works: Intelligent Design, a more popular work drawn from a number of his articles and lectures; and The Design Inference, a philosophical monograph in probability theory and explanation. The latter volume stems from his Ph.D. dissertation in philosophy, and is rather technical in parts. Given the nature of most monographs dealing with probability calculus, however, I found The Design Inference to be quite readable. Those who have no knowledge of the mathematics of probability may be put off, but in fact the level of mathematics and symbolic logic employed is not very difficult. There are no mathematical proofs in this book (as mathematicians think of such things). The main arguments (and lots of definitions) are given in ordinary prose, then translated into symbols. I think an intelligent layperson could grasp the main details of Dembski's argument. But what is that argument?

The subtitle of the monograph tells us the author's aim: to eliminate chance (as an explanation) through small probability. Dembski seeks to do this through his "explanatory filter," which he claims "faithfully represents our ordinary human practice of sorting through events we alternately attribute to regularity, chance or design." The purpose of the explanatory filter is to use probability estimates to "sweep the field clear of chance hypotheses," that is, to "eliminate chance entirely." This kind of informal logical reasoning is concerned with causes, that is, with causal explanations of why something happens. Dembski attempts to give a rigorous analysis of this kind of thinking, on the basis of probability.

The alternatives to chance as an explanation are regularity (or necessity) and design. The conclusion that some event is due to design comes from understanding the probability of that event to be quite small, against our general background knowledge. But Dembski rightly notes that this is not enough. We also need the event to be specified, and complex. A specified, complex event with small probability is, according to the argument, always a designed event.

Dembski has made a real advance in probability and information theory, with his attempt to give a rigorous logical definition of design in terms of "complex specified information" (here "information" is used in a mathematical sense to speak of patterns in the data). But I remain unconvinced by the explanatory filter. For example, Dembski reduces all kinds of regularity to natural laws. But that is too quick. Some regularities are not based upon the laws of nature. I once had a roommate who always put his pencils at a certain place on his desk, and they were always sharp. The probability of finding a sharp pencil on his desk in exactly that spot was very high indeed, but was not based upon a law of nature.

After reducing all highly probable events to natural laws, Dembski then reduces all natural laws (necessity) to algorithms and mathematical functions. And this will simply not do as a philosophy of science. Not all laws of nature are mathematical, nor can they all be given numeric values. They may not always generate a necessary outcome.

Dembski is on firmer ground when stating that the laws of nature, if we know them all, will make a particular event highly probable if that event is indeed caused by such laws. But we do not know all the regularities of the natural world. At best we can only talk about what is highly probable given our current knowledge. The filter demands that, in order to eliminate chance, we are aware of all the "chance hypotheses" for any given event. This demand seems out of reach, to my mind. So this filter does not in practice always eliminate chance, as Dembski wants it to.

Moreover, while Dembski insists that natural causes cannot generate complex specified information, it may be possible in the future—or so it seems to me— for us to understand how complex specified information can be generated by self-organizing physical systems. On the other hand, perhaps there are some biochemical systems so complex, and so specific, that design is the only possible explanation. In any case I will give Dembski this: his proposal is subject to empirical falsification. If he is correct, science will confirm it. If he is not, that also will be shown to be true. We should welcome further advances and debates on this matter, especially if they are scholarly in nature rather than vitriolic.

I believe that the intelligent-design movement has an important cultural role to play. Its members are rightly critical of the modern myths often told by scientists regarding the evolution of life from non-life (what is called pre-biotic evolution). We frankly have no knowledge of how life came from non-life. Scientists, especially in popular writing and speaking, sound as if they have well-confirmed theories about how life came about on this planet. And they do not. Life on this planet may be a direct result of divine design (a miracle), or perhaps it arose from as-yet-unknown natural causes. This debate has not been re solved. Either theory could be true, from all we now know. I admire the intelligent-design group for putting forward a bold, empirical hypothesis: the origin of life comes from some intelligent designer or other. No reasonable explanation will be forthcoming from natural causes (they claim) to explain complex and specific biological systems.

What about the claims of this movement to "insert" design back into science? I find this goal a rather odd one. If we are talking about all of the sciences, including economics, archaeology, and anthropology, then intelligent design is already a part of science. Archaeologists explain what might look at first like chance marks upon a stone as in fact the design of primitive humans. This stone was used as a tool, they will explain. So intelligent design is already a part of science. But like too many scholars today, intelligent-design folks often assume that real science is natural science. Hence when they say "science" they usually mean natural science unless the context demands otherwise. And they wish to add intelligent design to the paradigms and explanatory schemes of the natural sciences. Will they succeed?

Intelligent design, as a causal explanation, does not seem to be part of the natural sciences. This has to do with the focus of natural science upon the natural world, both for its object of study and its explanatory scheme. Natural sciences explain things on natural terms. And while it is true that intelligent agents like humans are "natural" objects, the natural sciences do not deal with the study of intelligent agency. This they leave to the social sciences. Animal psychologists are just beginning to study the intelligent behavior of apes. But notice that this is psychology, not biology. Intelligent agency is neither studied nor explained by natural science. Keeping this simple fact in mind would solve a lot of problems in current debates about science and culture.

The natural sciences can identify an event which, given our current knowledge, they cannot now explain. Perhaps, then, the event or object was designed. That is as far as natural science can go. And perhaps that is all the intelligent-design movement needs. Its members seem to want scientists to look and see if certain facts about the world, especially facts about the origins of living systems, exhibit signs or symptoms of design rather than natural causation. And I can see no reason in principle why astronomers or biologists should be unwilling to do so—apart, of course, from a prior commitment to naturalism as a world view.

I would make one final plea to both sides of this debate concerning the origins of life. Please do not think that the truth of the Christian world view turns upon your debate. Christianity is just as true if natural science can explain the origins of life, as it will be if intelligent design ends up being correct. But the debate itself should be interesting and informative. One hopes that both sides will maintain a scientific attitude to ward the evidence.

For my part, if I had to predict today how a future Angelic Doctor will reconcile theology and science, I would throw my hat in with O'Hear and Swinburne. I do not believe the intelligent-design folks will win the day. In other words, I accept the notion that life will some day be explained through natural causes, while insisting that God is the origin of all natural things, natural causes, and natural laws. In this way design and evolution are not opposites. Rather, evolution is based upon natural regularities, which in turn are created by God. Evolution is based upon design.

Alan G. Padgett is professor of theology and philosophy of science at Azusa Pacific University. He is a member of the Oxford Templeton Seminars on Science and Christianity, and has published books and articles in philosophy of science, philosophy of religion, biblical studies, and systematic theology—most recently, with Steve Wilkens, Christianity and Western Thought, Vol. 2 (InterVarsity).

Footnotes:

1. Swinburne summarized his technical arguments for a broader reading public in Is There a God? (Oxford Univ. Press, 1996).

2. By "Darwinism" they almost always mean a combination of biological evolution (a part of natural science) and philosophical naturalism.

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