Plantinga Summarises the Evolutionary Argument Against Naturalism

Here’s how Alvin Planti­nga sum­marises the evo­lu­tion­ary argu­ment against nat­u­ral­ism (EAAN) in his book Where the Con­flict Really Lies (p. 314):1

The basic idea of my argu­ment could be put (a bit crudely) as fol­lows. First, the prob­a­bil­ity of our cog­ni­tive fac­ul­ties being reli­able, given nat­u­ral­ism and evo­lu­tion, is low. (To put it a bit inac­cu­rately but sug­ges­tively, if nat­u­ral­ism and evo­lu­tion were both true, our cog­ni­tive fac­ul­ties would very likely not be reli­able.) But then accord­ing to the sec­ond premise of my argu­ment, if I believe both nat­u­ral­ism and evo­lu­tion, I have a defeater for my intu­itive assump­tion that my cog­ni­tive fac­ul­ties are reli­able. If I have a defeater for that belief, how­ever, then I have a defeater for any belief I take to be pro­duced by my cog­ni­tive fac­ul­ties. That means that I have a defeater for my belief that nat­u­ral­ism and evo­lu­tion are true. So my belief that nat­u­ral­ism and evo­lu­tion are true gives me a defeater for that very belief; that belief shoots itself in the foot and is self-​​referentially inco­her­ent; there­fore I can­not ratio­nally accept it. And if one can’t accept both nat­u­ral­ism and evo­lu­tion, that pil­lar of cur­rent sci­ence, then there is seri­ous con­flict between nat­u­ral­ism and sci­ence.

(Empha­sis mine.)

Prob­a­bly the most com­mon objec­tion to the EAAN is that bio­log­i­cal organ­isms with gen­er­ally reli­able cog­ni­tive faculties—that tend to pro­duce beliefs with true content—will sur­vive bet­ter than bio­log­i­cal organ­isms with gen­er­ally unre­li­able cog­ni­tive fac­ul­ties, and so the evo­lu­tion­ary process will select for the for­mer over the latter.

But this objec­tion misses the point. On nat­u­ral­ism, the evo­lu­tion­ary process does not care whether or not adap­tive neu­ro­phys­i­o­log­i­cal prop­er­ties gen­er­ally cor­re­spond to beliefs with true con­tent; it will select for adap­tive neu­ro­phys­i­o­log­i­cal prop­er­ties, not for neu­ro­phys­i­o­log­i­cal prop­er­ties that cor­re­spond to beliefs with true con­tent. And, on nat­u­ral­ism, there’s no rea­son to think that adap­tive neu­ro­phys­i­o­log­i­cal prop­er­ties do in fact gen­er­ally cor­re­spond to beliefs with true content.

This appears to put the nat­u­ral­ist in a slightly sticky sit­u­a­tion, to say the least. And things do look some­what bet­ter for the Chris­t­ian the­ist who believes, per­haps in a prop­erly basic way, that God exists and has (in one way or another) cre­ated human beings and the phys­i­cal world in such a way that human beings can have non-​​trivial knowl­edge about reality.

1 Planti­nga, Alvin (2012). Where the Con­flict Really Lies: Sci­ence, Reli­gion, and Nat­u­ral­ism. Oxford Uni­ver­sity Press.

Image from Wikimedia Commons.

Originally posted at TomLarsen.org.