Philosophy is notorious for not answering the questions it tackles. Plato posed most of the central questions more than two millennia ago, and philosophers still haven't come to much consensus about them. Or at least, whenever philosophical questions begin to admit of answers, we start calling them scientific questions. (Astronomy, physics, chemistry, biology, and psychology all began as branches of philosophy.)

A common attitude on Less Wrong is "Too slow! Solve the problem and move on." The free will sequence argues that the free will problem has been solved.

I, for one, am bold enough to claim that some philosophical problems have been solved. Here they are:

Is there a God? No.

What's the solution to the mind-body problem? Materialism.

Do we have free will? We don't have contra-causal free will, but of course we have the ability to deliberate on alternatives and have this deliberation effect the outcome.

What is knowledge? (How do we overcome Gettier?) What is art? How do we demarcate science from non-science? If you're trying to find simple definitions that match our intuitions about the meaning of these terms in ever case, you're doing it wrong. These concepts were not invented by mathematicians for use in a formal system. They evolved in practical use among millions of humans over hundreds of years. Stipulate a coherent meaning and start using the term to successfully communicate with others.

There are other, smaller questions that I think are solved, too, but for now I'm curious: Which philosophical problems do you think are solved, and what is the answer?