Full Idea
Reasoning will never make a man correct an ill opinion, which by reasoning he never acquired.
Gist of Idea
You can't reason someone out of an irrational opinion
Source
Jonathan Swift (Letters to a Young Clergyman [1720])
A Reaction
It would be hard to prove this, and someone full of irrational beliefs may have their rationality awakened by a sound argument. Nice remark, but too pessimistic.