I was arguing against:

On things I care about, I find the best position I can and act as though I'm 100% certain of it. When another position is shown to be superior, I reject the original view entirely.

with the implicit assumption that "best positions" are about states of the world, and not synonymous with "best decisions".

I guess we need to go back to Z. M. Davis's last paragraph, reproduced here for your convenience:

I agree that it would be incredibly silly to try to explicitly calculate all your beliefs using probability theory. But a qualitative or implicit notion of probability does seem natural. You don't have to think in terms of likelihood ratios to say things like "It's probably going to rain today" or "I think I locked the door, but I'm not entirely sure." Is this the sort of thing that you mean by the word judgment? In any case, even if bringing probability into the process isn't helpful, bringing in this dichotomy between absolutely-certain-until-proven-otherwise and complete ignorance seems downright harmful. I mean, what do you do when you think you've locked the door, but you're not entirely sure? Or does that just not happen to you?