Is Naturalism Irrational?

Alvin Plantinga

in Warrant and Proper Function

Published in print July 1993 | ISBN: 9780195078640
Published online November 2003 | e-ISBN: 9780199872213 | DOI:
Is Naturalism Irrational?

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In this chapter, I continue to argue that naturalistic epistemology flourishes best in the garden of supernaturalistic metaphysics. I do so by presenting two epistemological arguments against metaphysical naturalism; the first argument is for the falsehood of naturalism, the second, and more developed, is for the conclusion that it is irrational to accept naturalism. Crucial to both arguments is the estimation of the value of a certain conditional probability, P(R/(N&E&C)), where (roughly) R is the proposition that our cognitive faculties are reliable, N is metaphysical naturalism, E is the proposition that our cognitive faculties arose by way of the mechanisms of evolution (i.e., the mechanisms to which contemporary evolutionary thought directs our attention), and C is a complex proposition stating what cognitive faculties we have and what sorts of beliefs they produce. In the second argument I contend that (1) it is quite plausible to think either that the rational attitude to take towards the conditional probability mentioned above is the judgment that it is low or that the rational attitude is agnosticism with respect to it, and, (2) in either case, the devotee of N & E has a defeater for any belief he holds, including N. Further, since this defeater is an ultimately undefeated defeater (as I argue), it is irrational to accept N, since it is irrational to accept any proposition such that one knows one has an ultimately undefeated defeater for it.

Keywords: evolution; metaphysical naturalism; naturalism; naturalistic epistemology

Chapter.  12607 words. 

Subjects: Metaphysics

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