We generally interpret that question as an assault on our egos. If someone asks us to consider even the possibility that we're wrong, either about an opinion or a proposed course of action, we get very defensive.

It's very difficult to tell or suggest to another person that they're wrong. Chances are, you won't change their mind. If anything, you may end up having the opposite effect: the more defensive a person is acting, the less likely they are to reconsider, or even think about, exactly what it is they're defending.

I think considering the possibility that you might be wrong can often serve as the ultimate escape route. We get to a point where we're clinging to what we (think we) know and have trouble letting go. But being wrong can be a relief...so long as you ask it of yourself before someone else does. Then, it's an argument.

It's the question I (try to) never stop asking myself.