The problem is that there is no such thing as philosophy. You cannot go and "do philosophy", in the way that you can "do mathematics" or "do skiing". There are only people thinking, some well and some badly. The less they get out of their armchairs, the more their activity is likely to be called philosophy, and in general, the less useful their activity is likely to be. [...]

When philosophy works, it isn't philosophy any more, so the study of philosophy is the study of what didn't work. It's a subject defined by negation, like the biology of non-elephants.

I think there are useful kinds of thought that are best categorized as "philosophy" (even if it's just "philosophy of the gaps", i.e. not clear enough to fall into an existing field); mostly around the area of how we should adapt our behavior or values in light of learning about game theory, evolutionary biology, neuroscience etc. - for example, "We are the product of evolution, therefore it's every man for himself" is the product of bad philosophy, and should be fixed with better philosophy rather than with arguments from evolutionary biology or sociology.

A lot of what we discuss here on LessWrong falls more easily under the heading of "philosophy" than that of any other specific field.

(Note that whether most academic philosophers are producing any valuable intellectual contributions is a different question, I'm only arguing "some valuable contributions are philosophy")