[jadell]

Picking apart someone's belief through explaining their logical fallacies presupposes that they got to their belief through a logical process.

"Reasoning will never make a Man correct an ill Opinion, which by Reasoning he never acquired." -- Jonathan Swift, 1721.

To rephrase in a more modern way: You can't use reason or logic to get to someone to stop believing something they didn't use reason or logic to start believing.

[cortesoft]

I always like the short version: "you can't reason someone out of a belief they didn't reason themselves into"