Frequentists don't have a defined view of beliefs, they have a defined view of probability, namely that probability statements about events are statements about the limit of that event's frequency in an arbitrary number of trials. The Bayesian position is that probability can be understood as degree of belief. The Bayesian epistemological position is that all beliefs ought to be understood as probability statements. There is no Frequentist epistemology, a frequentist could hold any epistemology they wanted more or less.
I understand that this is the standard story, but don't find it satisfactory; hence was presenting my own "deeper" explanation (which I still regard as tentative).
After all, based only on what you've said, a frequentist could also be a Bayesian! This doesn't seem right, or at least doesn't seem to account for the fact that there seems to be a controversy between "frequentists" on the one hand, and "Bayesians" on the other.
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