While persevering with a belief may be an epistemic virtue in some contexts, stubbornness is not and its presence does not render knowledge better.
The tide comes in, the tide goes out. The only thing constant in life is change. But why is it that when we go to sleep we often wake up, and when we wake up in the morning we just go to sleep? People have been known to have dreams which reveal important truths. Why do they come in dreams and not in the light of daily thought?
A person who does not have a regular pattern of thought would probably qualify for being insane. And in that pattern is woven a system of thinking that includes what we know, what we believe and what we question. The daily routines of life keep us sane, I guess, or at least they keep our insanity under control.
Philosophers are those who think very deeply about things. They usually begin by doing something else. They are writers or scientists. They study mathematics, linguistics, psychology or some other field, and gradually work their minds into the rarified world of metaphysics. But along the road of trying to understand and define existence they arrive at points of contact where there has to be an idea expressed which formulates their thinking, a theorem, a touchstone to further thought and enquiry. But a true philosopher, like a true scientist, is gifted with the humility to be able to prove himself wrong.
Gottlob Frege, a German mathematician and philosopher, (1848 - 1925) thought that all cardinal numbers are extensions into the concepts of logical thought. After many years and further study he abandoned the theory. (Part of the reason for his change of mind had to do with Russell's Paradox (maybe I'll write about that some day if I have the nerve).) Frege was and still is an important philosopher.
The great lesson here is that a person who had worked for years to develop a system of thought that would explain things was ready and willing to give it up. I try not to think about the wrong opinions I held tenaciously to in my life. It wasn't hard to change my mind when I learned better. What was hard was being willing to change it. I feared that if I admitted I was wrong, even just to myself, I was also admitting my stupidity. Quite the opposite, in some cases the very thing I believed and was so certain of, even to the point of being called stubborn, was, in fact, superior to the so-called facts I was being given. While, at the same time, other ideas had to fall from the mental cart because they were wrong. I learned to let them go gracefully because I realized I wasn't stupid and that a mark of intelligence was being able to change one's mind.
There are people who stubbornly hold on to a belief even in the face of undeniable truth, or who insist on their own way of thinking and will not consider any evidence right or wrong to the contrary. Those people add little or nothing to the world. Theories of existence, anthropology, psychology, history, cosmology must come under scrutiny at all times and any thinker in those fields must be ready to change his mind if necessary. When an idea is challenged the result may be a better idea, or it may be a fist fight.
DB - The Vagabond
Below are some familiar phrases. Only one of them is legitimate. Which one is it and what is wrong with the others? That is your chore.
EXTRA: You get bonus point if you can think of other illegitimate ones.