Why beliefs are "sticky"

Leo Tolstoy, What is Art (1897) 

I know that most men—not only those considered clever, but even those who are very clever and capable of understanding most difficult scientific, mathematical or philosophic problems—can very seldom discern even the simplest and most obvious truth if it be such as to oblige them to admit the falsity of conclusions they have formed, perhaps with much difficulty—conclusions of which they are proud, which they have taught to others, and on which they have built their lives.