Open-minded people are willing to honestly consider evidence that could change their minds. Closed-minded people will not. No one is completely open-minded. No one is completely closed-minded.
There are two problems we face in order to cultivate the intellectual virtue of open-mindedness. The first is to learn what constitutes evidence, since most people are unreasonably persuaded because of anecdotal evidence, or fallacious arguments substituting for the lack of evidence, or even peer-pressure or the accidents of birth into a particular family or a different culture. The second is to learn to avoid confirmation bias as much as possible, which Michael Shermer calls "the mother of all biases." [In The Believing Brain, p. 259].
Once we learn about these problems and recognize them as the serious ones they really are, and that they stand in the way of a clear-headed investigation of the truth, we can proceed to be honest investigators of the truth. We would know what kind of evidence to look for and be better able to see any bias we might have and adjust for it.
There are two problems we face in order to cultivate the intellectual virtue of open-mindedness. The first is to learn what constitutes evidence, since most people are unreasonably persuaded because of anecdotal evidence, or fallacious arguments substituting for the lack of evidence, or even peer-pressure or the accidents of birth into a particular family or a different culture. The second is to learn to avoid confirmation bias as much as possible, which Michael Shermer calls "the mother of all biases." [In The Believing Brain, p. 259].