“You teach philosophy. What IS philosophy?”
In my first philosophy class, the professor began by saying something I've been repeating ever since:
“Philosophy asks just two questions. What can we know? And what should we do about it?”
American philosopher Wilfred Sellars was apparently (but not really) leaning more towards the first of those questions when he came up with the definition of "philosophy" that philosophers themselves like best: the attempt to understand how things (in the very broadest sense of that term) hang together (in the very broadest sense of that term).
Think of ALL the activities in which we try to build a coherent picture of the world and our place in it. Telling stories, studying history, doing mathematics, looking through telescopes, consulting horoscopes and priests and doctors and scientists and chicken entrails, arguing about whether ghosts could have caused that noise in the attic, photographing crime scenes, trying to remember exactly what happened last Tuesday evening, consulting Wikipedia, going to the psychiatrist or the Tarot reader, praying, deciding to volunteer for a cause, defending an economic policy, tapping something to see what kind of noise it makes ... whatever. How do all these activities fit together? What unified picture of the world we’re swimming in do they create—if any? How do we deal with it when they seem to contradict one another?
This leads to philosophers’ favorite sport: asking rude questions to people in other disciplines. “Yes, yes, I know you claim to be an expert in X. But tell me: how do you really know? What—more exactly this time, if it’s not too much trouble—do you mean by this, and that, and the other? And where did you get the evidence?” This is the core of the so-called Socratic method, in which Socrates goes around making fools of pompous ‘experts’ by asking naive-sounding questions to which (it turns out) the ‘experts’ can only give a mass of incoherent or contradictory answers.
But philosophers also like to take in and feed stray questions that seem to have been ignored or abandoned by everyone else:
Can I in fact know anything, for certain? (How? And is certainty even a necessary or plausible aim of knowledge? And if not, what makes some less-than-certain things good examples of knowledge, and others not so much?)
Is lying / cheating / stealing / torturing / killing ever defensible? (When? Why?)
Is the pain in my toe really a pain in my brain?
Is what’s morally right and wrong a matter of opinion — or are some people wrong about what’s right and wrong? (Hint: many, many beginning philosophers think the former is obviously true. Most philosophers, sooner or later, come to think that it can’t be true — even though that, in turn, seems to imply the weird idea that there are moral facts, out there in the world, independent of us.)
Can we describe a perfect society for human beings? If so, what’s it like? If not, why not?
Is there a god? (Or are there seventeen — and, if so, are some fatter than others?)
Is one molecule of water wet? If not, how can a big pile of them be wet?
“17 is a prime number”: is that a truth about the way the world is? If not, what sort of truth is it?
Is the world just stuff? (This is “materialism” or “physicalism.”) Or is it also some entirely other kind(s) of stuff — mind, soul, spirit, God, The Transcendent? Or (this is “idealism”) is the material stuff just an illusion conjured up by / for / inside the other kind(s) of stuff?
What sorts of freedom should be defended, or restricted? By whom? And why?
Physics tells us that color is just light bouncing off things — so what the heck do things actually look like?
Take any two examples of painting / sculpture / film / literature / drama / music; is it ever plausible to say that one is just objectively better than the other?
Will androids ever really think? Will they ever really feel? And how would we ever know?
How do I know Aunt Edith isn’t really just a cleverly-constructed android?
If all events are determined by earlier events, then isn’t my free will an illusion?
But if some events are undetermined by earlier events, then … isn’t my free will an illusion? (Despite this paradox, we all believe that we exercise free will all the time. Why?)
Speaking of illusions: how do I know Aunt Edith isn’t an illusion?
Speaking of the Aunt Edith illusion, how do I know that sitting-in-this-chair-reading-this-right-now isn’t an illusion?