There is a fine line between having a preference and being close-minded. For instance, I have been asked whether I would date someone of a different race. We’re all allowed to have our own tastes in people, but at what point does that cross into racism or bigotry?
I think the answer is that preferences are continuous while dogmatism is discrete. Having a preference differs from dogmatism in the recognition that the other extreme is possible, even if exceedingly unlikely. It means being able to envision dating someone of a different race, even if the combination of factors necessary for that to happen is unlikely to manifest in the real world.
Given that it will be difficult to distinguish between improbability and impossibility just by examining someone’s actions, this standard for dogmatism will mostly be important internally. Nevertheless, we are the ultimate arbiter of our thoughts - no one can force us to be convinced of beliefs we don’t want to be convinced of. So perhaps it is enough that we alone can employ this yardstick on ourselves.