Interesting no one has pointed out that those explicitly studying human behavior might have some insights on the subject as well, by which I mean psychologists.

Interesting no one has pointed out that those explicitly studying human behavior might have some insights on the subject as well, by which I mean psychologists. This is one the most unfortunate things I commonly run into when reading philosophy (or talking with those who study it): imagine if once physics became an established, separate scientific endeavor from philosophy (though it was once a part of it), and yet the majority of philosophers kept on inventing their own versions of physics (without ever doing experimental verification) and pretending the scientific branch didn't exist. I think this is a fairly accurate analogy for the relationship between psychology and philosophy. To be certain there are many subjects bordering on psychology which are still correctly in the domain of philosophy (e.g. free will or the 'hard problem' of consciousness), but then there are many more mundane issues which are already basically settled in psychology which philosophers still treat as if they were some deep fundamental aspect of reality. I suppose part of the difficulty is finding quality material in psychology, since it's a vast field with many sub-disciplines. That said, the search can be richly rewarding. There are experiments described in Gazzaniga's The Social Brain, for example, which profoundly changed my understanding of the human brain (and have remained consistent with much more reading over the decade following).