Overconfidence is Stylish
On William Strunk, author of the classic Elements of Style:
His original Rule 11 was "Make definite assertions." That was Will all over. He scorned the vague, the tame, the colorless, the irresolute. He felt it was worse to be irresolute than to be wrong.
An "irresolute" person is "Undecided or unsure how to act; Indecisive or lacking in resolution." You couldn’t ask for a clearer demonstration that we prefer overconfident people.
This passage shows about as well as anything why Strunk & White is a bad book. It mixes meaningless advice about style with statements about usage that are flat wrong (like telling people never to use "which" to introduce a restrictive clause). It is popular, though, so White (the book's real author) may have had a point about how to score points with the public.
Strunk was talking about writing. I could be wrong, but I don't think he would like your interpretation. It may have been that his philosophy concerning "resolution" extended to things other than writing, but the way I read it, he was saying that it is important to clearly state your ideas. As a writer this is a very difficult thing to do. It is about learning what is really in your mind and then being able to put that on the page. I think that is the confidence he was looking for. Once one's ideas are on the table we can discover whether there is anything to be confident about. To be irresolute means you have not even come that far.