Evidence · Case 09 · Atheism
Alvin Plantinga, Where the Conflict Really Lies
One exhibit from the free evidence repository at apologetics.pro.
Plantinga argues that the probability that our thinking faculties are reliable, given both naturalism and unguided evolution, is low or hard to assess, because evolution selects for survival-promoting behavior rather than for true belief. If that is right, the naturalist who sees it has a reason to doubt all of their beliefs, including naturalism itself.
Sources
Objections & responses
- If our faculties are unreliable under naturalism, they’re unreliable for evaluating Plantinga’s argument too. Doesn’t the argument saw off the branch it sits on?
This is a common reply, and Plantinga has an answer: the argument is a reductio. It assumes naturalism for the sake of argument, derives that the naturalist has a defeater for all their beliefs, and concludes that naturalism cannot be rationally held. The theist who runs the argument does not accept its premise and so does not inherit the defeater. Whether the reductio structure succeeds is debated, but the branch-sawing charge misreads the form of the argument.