When people think of philosophy and mathematics, they tend to think of either
a.) Logic, which a cynic might call mathematics with massaging to make it fit into philosophy departments.
b.) Philosophy of mathematics, where Platonism and intuitionism (and fictionalism and etc.) collide.
However, there’s a new group blog devoted to topics within “fields of formal epistemology and decision theory”; in other words, studying philosophy with mathematics rather than simply studying the intersection:
Since it’s a new blog, there isn’t much to link to yet, but I recommend the post on The Condorcet Jury Theorem, which is “often cited in support of the thesis that a group is a better truth-tracker than an individual.”