Philosophy, as I define it, is the "critical examination of pivotal concepts and beliefs." Critical examination involves looking at matters with a questioning attitude. Look for reasons for opinions and beliefs. Look for reasons against them. Attempt to construct (or find) arguments for positions -- and also against -- positions. Reject or revise positions/beliefs/theories accordingly. Question what things mean. But don't simply ask questions and leave it at that. Attempt to answer those questions. And look (critically) at whether those answers are satisfactory.
One can critically examine lots of opinions without it amounting to philosophy. One can explore whether there are weapons of mass destruction in Iraq. One can examine views about who would be the best candidate for president of the United States in the next election. One can look critically at the long term health effects of "trans fats." One can look critically at whether Christ and the Disciples at Emmaus was painted by Vermeer. But such critical examination is not philosophy (although it uses the same tools and can both lead to and benefit from philosophical examination).
Philosophy is the critical examination of pivotal concepts and beliefs. Before we get to the "pivotal" qualification, let's look at what concepts and beliefs are. As I am using the term "concept" (philosophers of psychology would have to be more precise) it is anything picked out by a noun phrase. So hat is a concept; money is a concept; art is a concept; so is eating, knowledge, person, elephant, and poetry.
By belief, for our purposes here (again, a philosopher who focused on such matters would have to be more careful), I mean something that is or may be believed. It is something picked out by a declarative sentence. Examples of beliefs are: "The Yankees will win the World Series this year," "There are more than five people in this room," "Today is Tuesday," "Paul McCartney wrote Yesterday" and "A guitar is a stringed instrument."
Again, critical examination of the concepts and beliefs I have mentioned is not always philosophy. I have said philosophy is the critical examination of "pivotal" concepts and beliefs. A rough synonym for "pivotal" in this context is "fundamental." A pivotal concept or belief -- again roughly speaking -- is concept or belief that a lot of other concepts and beliefs depend on. Often these are more general concepts and beliefs. "Hat" is a concept and if you're going to follow some rule that you must (or must not) wear a hat at some religious ceremony, it can be important to know what a hat is. (Or if your spouse tells you to go out and buy a hat.) But in the grand scheme of things (and much of philosophy is concerned with the grand scheme of things) not much depends on whether something is a hat.
Contrast hat with person. Now you and I are pretty good (although not perfect) at determining what is a person and what is not (maybe better than we are at figuring out what is a hat and what is instead a scarf or cap). But of course there are important issues where this is in question. Some (but not all) of the debate about the morality of abortion involves the question of whether a fetus is a person. The question also arises at the end of life when a human body is lying in a bed kept biologically alive by machine and tests indicate that there is no brain activity. And one can imagine other circumstances (extraterrestrial visitors) where the importance of the extent of the concept would be obvious. But the concept is important even in cases where we have no doubt that something is a person. I (and you, I hope) think it would be wrong to kill a person for no good reason without that person's consent. You, I hope, have no doubt that I am a person. So, you probably think it wrong to kill me without my consent for no good reason. Of course some of you may think that consent (although it is a pivotal concept) is irrelevant here. Some of you might think it would be wrong to kill me even if you did have "good reason" (although that is another concept needing exploration). Some of you might think that whether I am a person is irrelevant here and what is relevant is that I am a living thing (although I wonder whether you would refrain from killing a living bacterium, scallion, or mosquito). And what is it for something to be wrong (wrongness -- you guessed it -- is a pivotal concept)? And what is it to kill (ditto)?
Now there is no sharp line between pivotal concepts and non-pivotal concepts. It is surely a matter of degree. It still makes sense to speak of some concepts as "pivotal." Here are some concepts I think of as pivotal: cause, knowledge, God, mind, value, material object, freedom, beauty, and art.
What about pivotal beliefs? Not all beliefs involving pivotal concepts will be pivotal beliefs. Did my cat cause the lamp to fall over? While cause is a pivotal concept, but this belief is not a pivotal belief. Not much (although not nothing) depends upon it. Whether everything that happens has a cause, however, is a pivotal belief. Other arguably pivotal beliefs: "There is a God who created us and loves us." "Knowledge is justified true belief." "Something that is not beautiful is not art." "Killing persons is wrong." "Human beings have free will." "We cannot know anything about anything we have not experienced." "Democracy is the only justifiable political system." "Mental phenomena are simply functions of the brain." "The only things that ultimately exist as things that are explanable in terms of physics." "The only things that are art are things which are beautiful in some way."
Now I don't believe in all these "beliefs," but each one is such that much depends on whether it is true.
One might think that since we are asking about concepts and beliefs, philosophy is about what people think. And in a sense it is. But the philosopher as such is not concerned with whether people as a matter of fact believe something. We'll leave that to the pollsters or the psychologists or sociologists. The question is whether the belief is true. That cannot be determined by poll (unless the belief is about sociological matters, such as whether in the United States in 1967 the Beatles were more popular than Jesus). So typically "social science" investigation will not be directly pertinent to philosophical exploration.
Often philosophers do analysis and attempt to understand certain pivotal concepts in terms of others. So a philosopher may propose that knowledge is justified true belief, that causation is constant correlation, or that art is the expression of emotion.
One thing philosophers do, then, is to critically examine such views. A broad, coherent view about a matter could be called a "theory." Philosophers come up with theories about pivotal matters. Philosophers also critically examine theories which have been proposed by other philosophers.
As philosophers we spend a lot of time looking at views that are false. It is important when a philosophical view is false to understand why it is false, what is wrong with it. This is part of what is involved in critical examination.
Like any other discipline philosophy has branches. The three main branches of philosophy are metaphysics -- the study of the nature of reality, epistemology -- the study of nature of knowledge, and axiology -- the study of the nature of value. Logic, which is often taught in philosophy departments, is in part a branch of mathematics, in part a tool which philosophers use in their work, in part an aspect of epistemology (in that it is a study of the nature of good reasons, reasons which may lead to knowledge) and in part an aspect of axiology (in that involves an exploration of the nature of good reasons).
In addition to those branches there are often taught in philosophy departments courses with titles of the form "philosophy of X." Philosophy of science explores the nature of science and philosophical questions that arise in, and at the foundation of, science. Philosophy of religion explores philosophical questions that arise in, and at the foundation of, religion. Philosophy of art, naturally, explores philosophical questions that arise in, and at the foundation of, art.
So what are the philosophical questions that arise in, and at the foundation of, art? Here are several:
One thing philosophers do is to make distinctions. So, for example, Collingwood distinguishes what he calls "art-proper" from other things such as "magical art," "craft," "amusement," and so on. An important distinction at the center of the field is between "art" and "aesthetics." Aesthetics, as this term is currently understood, involves certain kinds of judgments ("aesthetic judgments") about things, often, but not always, involving beauty. One can make aesthetic judgments about things which are not art, such as sunsets and hands. Philosophy of art, on the other hand, concerns philosophical questions about the nature of art, not all of which involve an aesthetic appreciation, and not all of which involve beauty.
I mentioned already that philosophers use logic as a tool. This is because philosophers are concerned to make and criticize arguments. As philosophers use the term "argument" it is a defense of a position. An argument has conclusion, a statement which is argued for. An argument also has premises, which are claims which are appealed to in defense of the conclusion. It is also usually useful to isolate the form or structure of an argument, which helps to make clear how the premises are supposed to support the conclusion.
Here's an example of an argument:
Some of you might immediately think "of course!" Others may be ready to object. Both groups of people, however, should ask whether this is a good argument. Has a good reason been given for the stated conclusion? And this question can be broken down into two questions: First, are all the premises true? Second, is the structure of the argument such that if the premises were true, the conclusion would then have to (or at least probably) be true? I have made this case a bit easier by laying out the argument with explicit premises and an explicit conclusion. Usually in books and articles the arguments won't be laid out quite so clearly. One will have to tease out what the premises are.
For this particular argument it may be difficult to lay out the form precisely. And, furthermore, in trying to do so, one might find oneself having to puzzle about what it means to say a work is art is something (viz., a physical object). (Bill Clinton may be the one who gets into the book of quotations, but philosophers are often in a position to say "It depends on what the meaning of 'is' is.") And one might find that premise 3 is not all that clear either. For example, what is included in the "et cetera?" Are all human beings presumed to be destroyed? After all, if a poem can be stored on a computer disk, can't it be stored in a brain? (Fahrenheit 451, anyone?)
And then if we do reject the conclusion, and admit that not all works of art are physical objects, then what belief do we put in its place? Are some works of art (paintings, maybe) physical objects, and others (poems, symphonies) not? Or are no works of art physical objects? And if that, what are they?
So, why bother to do philosophy of art? Well, while I feel philosophy is valuable in general, I actually don't think it is requisite that everyone do philosophy of art. While art and beauty are pivotal concepts, it is not important that everyone understand about them. Some people want to understand. All power to them. But someone who cares about art, someone who does art, ought to try to understand.
Socrates was an important philosopher early in the development of western civilization. (He died in 399 B.C.E.) Socrates made a practice of questioning all sorts of people whom others might consider wise. He questioned politicians, military generals, priests, law professors (or what was roughly equivalent to that in their society), and poets. In each case he'd find people with strong beliefs who thought they understood what they were doing. In each case by the end of the discussion with Socrates they would realize that they don't understand what they are doing. Generals didn't understand what courage was. Priests didn't understand what piety was. Politicians didn't understand what justice was. And so on.
Spiders make webs. It is not important that they understand what they are doing. They do it (and generally do it quite well; the ones who didn't haven't passed on their genes to subsequent generations). Bees make honey. They don't need to understand. Water runs downhill. It doesn't understand what it is doing. And people too do things they don't understand and don't need to understand. I walk. I haven't taken courses in kinesiology. But if someone specializes in some field or wishes to be an expert, she or he should understand what it is she or he is doing. And this involves critically examinating pivotal concepts and beliefs that arise in, or at the foundation, of that field. If, therefore, one wishes to be an artist (not as a casual hobby, but as master), or if one intends to teach art to others, one should have an understanding of what art is, how it relates to emotions, and so on.