Humans are not truth machines. We are machines/organisms composed of many practical problem solving components/modules. Actually, many of these modules often work against each other.
Our brains are not built to crank out truth. Instead, our brains are geared to produce desired results — results that secure survival and successful reproduction.
And if truth must be sacrificed for these supports for reproductive success, then the brain joyfully obliges ! See my post on the “Tooth Fairy“.
Disciplining parts of our mind to produce some measure of truth is then no easy matter. But we must take care. Our mind is geared toward practical skills to keep us alive, if we ignore them for the sake of some truth which ignores our survival, we can suffer. (Reality bites !)