Religion & Law

Metaphysics of Biology

By John Pieret

The usual line of argument endorsed by most critics of ID and other forms of creationism is that science in general, and evolutionary biology in particular, makes no commitment to metaphysical naturalism. Metaphysical naturalism is typically construed as [Michael] Ruse describes it: as an ontological thesis, stated with a priori certainty, about the absolute non-existence of entities other than those posited by our current scientific theories. If this is what metaphysical naturalism is, then it is beyond what science can tell us. Evolutionary biology hardly needs any such assumption. In this sense, at least, the usual line of argument is correct. But there is no reason why naturalists should accept such a view of metaphysics, unless, of course, the ultimate purpose is to reject the very possibility of metaphysics. Such a rejection was a rather common desire among twentieth-century philosophers, though, as usual, with many antecedents in the empiricist tradition, most notably, Hume.

But this not the only view of metaphysical commitment. It is, for instance, not the view of metaphysics ... taken to consist of a set of foundational assumptions supposed to be respected by all admissible scientific theories. Once we view metaphysics in this way, as Pierre Duhem -- a practicing Catholic and superb philosopher of science -- pointed out a century ago, science is never innocent of metaphysics. This, presumably, is the kernel of truth in [Phillip] Johnson's claim that methodological naturalism necessarily collapses into metaphysical naturalism. Descartes, Huygens, and Leibniz assumed the mechanical philosophy as they pondered on the motion of planets. Newton, at least in practice, advocated more tolerance about permissible explanations, but put a much greater weight than Descartes on quantitative agreement between the predictions of a theory and the phenomena to be explained. ...

When we do evolutionary biology, we assume the metaphysics of that theory: the type of mechanisms it admits, that is, blind material interactions with no directionality built into them. We accept the role of chance and we accept the lawlike operation of natural selection and all principles of the physical science. When one such 'blind" mechanism fails, we seek another that is equally '"blind." This is all that metaphysical naturalism amounts to, no more and no less.

- Sahotra Sarkar, Doubting Darwin?

Full post as published by Thoughts in a Haystack on November 15, 2008 (boomark / email).