High certainty does not entail inflexibility, narrow-mindedness, nor dogmatism.
For instance, I have high certainty that the Earth is not flat. This certainty is evidenced by the fact that if I were given the opportunity to bet accordingly under sufficiently reliable conditions, I would do so. I might even give the Flat-Earther better odds. But I am not dogmatic in this belief, for I can describe conditions under which it would be rational to change my mind—conditions under which I would change my mind and conditions under which I would concede to losing any such bet.
Moreover, while it can be rational to disbelieve in, say, magical powers, it can also be irrational to continue to disbelieve in them in spite of evidence to the contrary. I do not believe in the magic of Harry Potter, but if I observed the kinds of things Harry Potter observes, I’d be increasingly irrational to deny magic as those observations accumulated.