[habitue]

This just doesn't explain things by itself. It doesn't explain why humans would care about reasoning in the first place. It's like explaining all life as parasitic while ignoring where the hosts get their energy from.

Think about it, if all reasoning is post-hoc rationalization, reasons are useless. Imagine a mentally ill person on the street yelling at you as you pass by: you're going to ignore those noises, not try to interpret their meaning and let them influence your beliefs.

This theory is too cynical. The real answer has got to have some element of "reasoning is useful because it somehow improves our predictions about the world"