Moral humility is born out of uncertainty. Bertrand Russell, the great British philosopher was inspired by John Locke. Locke always emphasized that all knowledge is uncertain. People should always take into consideration that they might be wrong. This should be remembered whenever we deal with others who have different opinions from us. This leads directly to tolerance in practice. Live and let live. Reject fanaticism in favour of moderation.
Russel called this the liberal outlook. it lies not in any particular beliefs but rather in how they are held. Instead of being held dogmatically, they are held tentatively with the understanding at all times that new evidence may show we were mistaken and will then abandon our beliefs. This is the opposite of how theologians hold beliefs.
Critical thinking is not utopian. It adopts instead what I have called the Russell principle, after Bertrand Russell. He said, “it is wrong to inflict a certain harm to achieve a dubious good.The more uncertain the future goal one is trying to achieve, the less the harm one must employ to obtain it.” It might be permitted to inflict violence to avoid a certain greater harm, but it makes no sense to inflict a certain harm to avoid an uncertain future harm unless that future harm is much, much worse than the means. This always requires a rational analysis of the probabilities. The more dubious the future goal the more gentle must be the means employed to obtain it. The problem with many modern revolutionary utopians is that often they inflict a certain substantial present harm to achieve not just a dubious future goal, but an impossible goal!
I prefer modest goals and modest means. Many believe such views, especially in religion or politics, is too tame. They prefer missionary zeal. I don’t. I prefer moral humility.