Some people are of the opinion that the philosophical discussion around theism and naturalism as conceptions of reality should consist in a comparison of their respective “theoretical virtues.” I think this is exactly wrong. In fact, I think that framing the discussion in this way is a trap. Naturalism can always win the “theoretical virtues” debate, even if theism is true. In other words, I think the debate about “theoretical virtues” is worthless. Moreover, I think that a careful consideration of the “theoretical virtues” of naturalism reveals how empty it is. Here is why.
(1) Suppose a naturalist and a theist are debating the “theoretical virtues” of their respective world-pictures. The theist posits a cosmos of contingent things entirely dependent for its existence upon a necessary first principle called “God.” Can the naturalist can simply appropriate this conception of things and call the first principle “natural,” even though it does it all the same “work” and satisfies the same metaphysical description as God in the theistic system? If he cannot, then the debate about theoretical virtues is pointless; one must attend to whether things really are the way they are being described by the theist. But if the naturalist can appropriate and “naturalize” the theist’s system, then naturalism would be more “parsimonious” than theism, even though it does not differ in terms of actual content, simply because it talks about everything using one word (“natural”) rather than two (“God” and “not-God”, “natural” and “supernatural”).
The only disadvantage of the theist was that he approached everything from the point of view of the difference between the contingent cosmos and the necessary first principle, whereas the naturalist thought of everything from the point of the co-belonging of first principle and cosmos in a single category. Because he approached things from the point of view of a difference, the theist had to use two categories. Because the naturalist approached things from the point of view of a co-belonging, he got to use one category. But this difference of approach gives the impression that the naturalist is being more parsimonious, even though ex hypothesi there is actually no difference in content between the two theories. So the victory of the naturalist from the point of view of “theoretical virtues” is an empty one.
The same point can be put more formally, for those so inclined. Suppose we are trying to explain some phenomenon p. It will always appear more parsimonious to explain p in terms of some special X that can do whatever a Y is supposed to do rather than to speak of Y as doing something special which most ordinary Xs cannot do. But if the notion of an X can be expanded to include the work of a Y, then there is no difference in actual content between the persons who believes only in Xs and the person who believes in Xs and Ys. There is simply a decision to speak about things using one word rather than two. But this is in fact an empty victory in the debate about theoretical “virtues,” because the decision to talk about Ys in the first place was motivated by the fact that not every X can do the relevant theoretical-explanatory work. So one is left with two perspectives which are equal: one can talk about Xs that can do the work of a Y, if one is concerned to subsume everything within a single category; or one can talk about Xs and Ys, if one wishes to highlight a critical difference between Xs in general and that which is being posited to explain the phenomenon p in question. There is no difference in content, only a difference in direction of approach which motivates a different use of language.
(2) Suppose then we have two naturalists who believe in a necessary, natural first principle on which the cosmos of contingent things depends for its existence. One of them, the “former” theist, attempts to relate to this natural first principle in typically religious ways: through contemplation, prayer, and perhaps even acts of worship and participation in a “naturalized” interpretation of some popular religion. The other considers this either pointless or inappropriate given that the first principle is “natural.” But the “former” theist can respond in two ways. He can either say that some natural objects are worthy of worship, or else he can say that whether or not the natural conception of the first principle demands that one worship it, it is nevertheless is fitting and appropriate for the reasons theists typically give for God, e.g. because He gives us existence and makes it possible to enjoy good things. Thus, he remains a naturalist who believes all the same things as when he was a theist, apart from the fact that now he calls the first principle “natural”, and who engages in religious practices.
Has he ceased being a naturalist in relating to the first principle this way? If not, then naturalism is perfectly compatible with the truth of theism and the practice of religion, so long as one calls the first principle “natural.” This is the emptiness of the debate about “theoretical virtues.” One could even be a Christian naturalist: God is natural; Christ was natural; the resurrection was a natural event; etc. But if he has ceased to be a naturalist at this point, i.e. if the force of the category of the “natural” is that it excludes worship or religious attitudes, then it becomes obvious that the difference between naturalism and theism is not a matter of content but of practice. Both the naturalist and the theist can believe in the same thing: a necessary first principle on which the whole cosmos of contingent things depends for its existence. Naturalism turns out simply to be the refusal to worship anything.
(3) If the true heart of naturalism is simply the refusal to worship anything, if the true force of the use of the word “natural” is to empty something of its religious significance, then once more the character of naturalism as a bias and an ideology comes into clear relief. It is a picture of the world developed on the basis of the assumption that nothing is worth worshiping. It is not really an attempted explanation of things and its “theoretical virtues” are in fact empty. This is clear when one considers that it could posit exactly the same picture of the world as theism, only it uses “natural” to describe everything and so is more “parsimonious.” Naturalism thus starts with an idea in mind of what reality must be and then attempts to conform everything to that idea, rather than proceeding on the basis of the things themselves. It sees everything only from one point of view and therefore is an ideology.