Desirable social change doesn't happen without practice, except by accident. Artists often wait for an accident called "inspiration". Suppose that weren't the case?
Art can be a laboratory in which to test ideas that one's situation forbids testing elsewhere (let's say in "real life"). (In much of the art world, the above sentence is, alas, one of those ideas.) That's assuming, of course, that people can have more than one idea at once, and can even have thousands of ideas in a lifetime. Many people have been told that's impossible, and that's how they act: as if the four or five ideas that make up their "identity" were slightly malleable, but not increasable. People often judge an idea as if they were weighing the desirability of it being the only idea they'll ever have. (Think of all the success stories about billionaires which begin "He had
just one idea: Bendable Forks.")
An artwork can hold an idea which isn't yet heavy enough to stay down by itself. I can walk away from that artwork and come back years later -- the idea hasn't floated away. Some ideas I wouldn't recognize or even remember if I didn't remember artwotk where I coudl find them. One of the practical ways art promotes and protects multiple ideas is by giving us someplace to put them.
Humor is a temporary anaesthetic to fear. Fear includes the desire for someone else to make decisions for you. Contributing to the climate of fear and emotional / intellectual anxiety which serves our current leaders so well is a job commercial art performs easily. Too many noncommercial artists attempt to perform with difficulty the jobs commercial art performs easily.
Thoughtfulness is a desirable political state. So art that provokes thought can be "political," even when its content is abstract or everyday. Explicitly political content needs to be made thought-provoking, since we are numbed to it, not just by the culture we live in, but also by the numbing character of our political system itself. It's desirable for any work of art to contain an irritant that disturbs the comfort of anyone who already "agrees." This can be a surprising shift in tone, an element that doesn't fit, an awkwardness or "wrongness" in music, color, movement, etc.--anything that calls for more thought and change on the part of perfomer and audience as well as the world. Art is utopian in the best sense, where utopia is defined not as a final paradise, but as a profusion of new ways to imagine and solve new and more productive problems.
Art should suggest that problems are there to be solved, even if, or because, the characters in the artwork didn't solve them. In commercial art, everyone identifies with the main character's apparent relief that he died before having to solve the problem.
Art needs to educate because nothing else will -- we no longer have an education system in the U.S. Anyone who knows anything is an autodidact, and despite the contempt many have for "learning", everyone enjoys becoming smarter. Art doesn't have to become school to explore that enjoyment.
Art can connect ideas and events in a way that the news media, with its carving up of information into articles, features, and columns, never can. It can juxtapose events from widely differing scales, fields, and times, often in counter-intuitive and revealing ways. So one job of artists is to defend and promote the counter-intuitive; this is essential when most immediately available arguments turn out to support the way things, and people, already are.
Artists should declare their work to be in opposition to war on Iraq, even if that work consists of smearing old LPs with chili paste while reciting Chaucer. The people who don't want our work to be funded want to spend billions on untested and unreliable missile systems, so we needn't feel bad about needing money. (We try to remember that there's a difference between needing money to live, which we all do, and needing money to make art, which Spielberg does.)
Art needs to display its feelings, not just the fact that it feels. Art should argue against any situation in which people say the art is beautiful because otherwise nothing would be.
Activism needs art. Nearly everyone gets bored at rallies when all that happens is rant. The most successful public events entail as much art as talk. And the most absurd, apparently off-base art can draw more attention to a demonstration or talk than the best speakers.
Art should leave us with the feeling that the work and the fun are just beginning. The world changes, whether we want it or not. We wish to become experts at wanting it. No-one can become an expert without practice. Art can become a world (individual and social) in which we practice, and have help practicing.