The question of the week

How do our atheists/naturalists brothers and sisters, or rather put those who subscribe to evolutionary naturalism arrive at their moral knowledge?

Alvin Plantinga and William Lane Craig help us formulate the below impregnable argument. Have a look at the premises and the conclusion, then try to formulate a rebuttal; by whacking down each premise. After this, please help me answer the opening question above.

  1. The probability that our cognitive faculties are reliable, given naturalism and evolution, is low.
  2. If someone believes in naturalism and evolution and sees that, therefore, the probability of his cognitive faculties’ being reliable is low, then he has a defeater for the belief that his cognitive faculties are reliable.
  3. If someone has a defeater for the belief that his cognitive faculties are reliable, then he has a defeater for any belief produced by his cognitive faculties (including his moral beliefs).
  4. Therefore, if someone believes in naturalism and evolution and sees that, therefore, the probability of his cognitive faculties’ being reliable is low, then he has a defeater for the reliability of his moral beliefs.

Because our moral beliefs have been produced by faculties aimed at survival, not truth, we can have no confidence that our moral beliefs are true.

Plantinga argues that naturalism is self-defeating because if our cognitive faculties have evolved by naturalistic processes, they are aimed, not at truth, but at survival, and so cannot be relied on to produce true beliefs.
William Lane Craig adds to this and says that ‘Because our moral beliefs have been produced by faculties aimed at survival, not truth, we can have no confidence that our moral beliefs are true.’

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