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Are Methodological Naturalism and Philosophical Naturalism the Same? A Dissent


In a previous post, I argued that methodological naturalism, as compared to philosophical naturalism, is a reasonable and neutral working principle limiting everyday science to natural causes. Afterwards, I corresponded with Center for Science & Culture Senior Fellow Paul Nelson, a philosopher of biology, who has a different view.

Dr. Nelson argues that in practice, there is effectively no difference between methodological naturalism and philosophical naturalism. He notes how methodological naturalism specifically excludes inferences to causation by whatever is not “natural.” Nelson is joined by mathematician William Dembski in his book The Design Revolution. He argues that while methodological naturalism does grant that there may be more to reality than natural causes, from the perspective of working scientists it is the same as philosophical (anti-teleological) naturalism. Methodological naturalism, Dembski observes, specifically excludes intelligent design from science because, by definition, design and teleology have been rendered “empirically undetectable.”1

Philosopher Barbara Forrest, however, a critic of intelligent design, has a different take. Forrest, in her article “Methodological Naturalism and Philosophical Naturalism: Clarifying the Connection” (2000), doesn’t see methodological naturalism as disallowing the logical possibility of supernatural causes. She sees any assertion otherwise as nothing more than epistemological arrogance, since no human can have exhaustive knowledge of all there is. She goes on to argue, however, that methodological naturalism does not allow enough of a logical possibility to provide sufficient warrant for acknowledgement of the supernatural.

Forrest, unlike Dembski, does not believe that methodological naturalism necessarily entails philosophical naturalism. She reasons, however, that based on the success of methodological naturalism, and the great knowledge it has contributed to the world, along with the simple dearth of evidence for the supernatural, that the “only reasonable metaphysical conclusion” from an empirical and logical perspective is philosophical naturalism.2 She sees methodological naturalism as procedural and epistemological, as opposed to philosophical naturalism which is a metaphysical position. The heart of Forrest’s argument is as follows:

Adopted in the sciences because of its explanatory and predictive success, methodological naturalism is the intellectual parent of modern philosophical naturalism as it now exists, meaning that philosophical naturalism as a world view is a generalization of the cumulative results of scientific inquiry… It is neither the a priori premise nor the logically necessary conclusion of methodological naturalism, but the well grounded a posteriori result.

I don’t think this holds up logically. Methodological naturalism has, indeed, shown great success in describing the natural world through physics and chemistry. We think, notably, of the incredible technological advances in medicine, robotics, cell phone technology, and soon-to-be-ubiquitous self-driving cars. But descriptions are not explanations, as they don’t tell us why things are the way they are. There are a great many things we can’t explain or describe that seemingly defy physics and chemistry, such as human consciousness, dark matter, or life itself. So I think Forrest displays considerable “epistemological arrogance” in saying that philosophical naturalism naturally follows from the success of methodological naturalism.

Consider Newtonian physics, the paradigm for the physics of everyday life. At a time when people believed bodies could only interact through contact, Newton introduced the notion of action at a distance. He challenged the mechanical philosophy of the day by focusing on forces operating in nature that could be mathematically described, though not observed. Forces, such as gravity, could produce effects that did not require any mechanical contact and had no apparent cause. This approach to science is known as “phenomenalism,” where phenomena can be described without knowing actual causes. For Newton, this permitted belief in the divine order of the universe by a creator whose work could be described (but not explained) by mathematics. The same approach was taken by the great astronomers whose work Newton synthesized — such as Copernicus, Kepler, and Galileo, who likewise believed God ordered the universe through mathematical laws.

Both Dembski and Forrest would agree that methodological naturalism is, in principle, metaphysically neutral. Both would also agree that methodological naturalism has no bearing on what practicing scientists may actually believe about the supernatural. Yet Dembski thinks that methodological naturalism effectively impedes scientific progress, in that it limits science to pursuing only natural causes. Forrest counters that methodological naturalism keeps science focused where it should be, on natural causes.

Clearly, there is no reconciling these two positions. However, is it necessarily the case that those who practice methodological naturalism, particularly those who are theists, feel that God would leave no empirical evidence of himself, as Dembski asserts of them? And is it necessarily the case that a non-theist who accepts methodological naturalism is not open to intelligent design? I don’t see it as the case that a non-theist who practices methodological naturalism could not possibly, at some point, infer design if sufficient empirical evidence were presented. And I don’t see where it is logically necessary that a theist who practices methodological naturalism as a principle must also believe design is not empirically detectable.

In 1997, the incomparable Christian philosopher Alvin Plantinga, now the John A. O’Brien Professor of Philosophy Emeritus at Notre Dame and this year’s Templeton Prize winner, published a paper widely read in Christian philosophical circles, titled “Metaphysical Naturalism?3 His purpose was to demonstrate that methodological naturalism is a flawed doctrine. Plantinga, like Dembski, believes that “in many areas” science is simply not neutral. While he admits that methodological naturalism is supposedly neutral, he argues that the “actual practice and content of science” belies such a notion. In his refutation of methodological naturalism, however, he does note two reasonably strong arguments for adopting methodological naturalism. The one I will focus on is Duhemian science, which is the view that I advocate.

Pierre Duhem (1861-1916) was a French physicist, mathematician, and practicing Catholic. Duhem was concerned that disagreements over metaphysics made it difficult for physicists of such differing views to work well together. Plantinga quotes Duhem:

I have denied metaphysical doctrines the right to testify for or against any physical theory….. Whatever I have said of the method by which physics proceeds, or the nature and scope that we must attribute to the theories it constructs, does not in any way prejudice either the metaphysical doctrines or religious beliefs of anyone who accepts my words. The believer and the nonbeliever may both work in common accord for the progress of physical science such as I have tried to define it.

Duhem argued that when workers in the field of physics impose their metaphysical views on physical theory, it makes it hard for those with differing metaphysical views to accept the physical theories of others. However, if science is done in a manner independent of metaphysics, then workers, regardless of their metaphysical views, can collaborate and cooperate. They are free to move science forward regardless of their other commitments.

Plantinga admits this view appeals to him in being “maximally inclusive.” Yet he rejects it because though much of science is Duhemian, he doesn’t see all science that way. He describes “Augustinian science,” which allows for theological or philosophical assumptions, as a valid form of scientific inquiry, and feels Duhemian science should include Augustinian science.

So it seems I am a bit at odds with Dembski, Nelson, and Plantinga, which seldom happens. Where does the disagreement lie? I believe wholeheartedly that design is empirically detectable in nature. The fact that some bring an a priori view of philosophical naturalism into science, while others feel it follows a posteriori from methodological naturalism (as with Forrest), is in my view unfortunate but immaterial to the goal of methodological naturalism to be neutral on the metaphysical (as Forrest maintains).

For me, what is important is that all scientists, irrespective of their metaphysical views, should be able to express their own sincere conclusions without fearing derision or reprisals in the scientific field. Clearly, those with an a priori and some with an a posteriori bias against design, such as Forrest, violate the Duhemian spirit in word and deed. That, in my view, is the real and distressing issue in the scientific community today.


(1) William A. Dembski, The Design Revolution: Answering the Toughest Questions About Intelligent Design (Downers Grove, IL:2004), p. 169-171.

(2) Barbara Forrest, “Methodological Naturalism and Philosophical Naturalism: Clarifying the Connection,” Philo, Vol. 3, No. 2 (Fall-Winter 2000), pp. 7-29.

(3) Alvin Plantinga, “Methodological Naturalism? Part 2,” (1997).

Photo: Statue of Philosophy, Reading Room, Library of Congress, by Carol M. Highsmith, via Flickr.