What is an artist for? Judging by this year's Archibald finalists, the job of an artist is to take the place of a camera, to add something a little expressive around the edges and not let the heads get too big (be they artist ego, subject, or the painting itself).

Size is an issue and it must be tasteful, say our esteemed art critics, and so, please, heads no larger than life-size. Duly noted.

We like our artists to be expressive, to let us see the world through their eyes. That is a given. But the weight of public opinion demands that artists do not stray too far from the concept of "community standards".

Art controversies are debates about what is acceptable self-expression.

The argument is that there are responsible limits to artistic freedom. It is all well and good to express yourself, but if you go too far the public reserves the right to call the police.

Another popular and recurring debate about art is whether new forms of art are really art at all.

There has been a strong conservative backlash against contemporary art in the past few years that has gained strength since the onset of the global crisis in capitalism.

The art critic Jonathan Jones, writing in The Guardian arts blog, claims all this new fangled so-called art is the hand-maiden of vacuous contemporary culture. It does not matter that an artist claims to be critiquing contemporary culture, making pretty, meaningless objects that sell has just made a bad situation worse.

These sorts of social constraints on art are a challenge to anyone who wants to make it. There's a pact between artist and audience, which acknowledges that to work in a certain medium is to carry a range of expectations.

Being a painter is a largely redundant practice nowadays and no one really expects a painter to be anything other than a creator of pleasant decor.

If they choose to do otherwise, they risk the wrath of a conservative public who know what they like.

If an artist works in a newer medium, such as video or performance art, then the artist will probably accept that, in Australia at least, they are not going to get a lot of respect. You cannot just switch on a video camera and film yourself slapping your face and call it art, can you?

Some artists do exactly that; they stretch the definition and practice of art. And the question remains - why?

The short answer is that most contemporary art is created in the tradition of the avant garde.

Most people mistake this tradition for wilful obscurantism, when in fact the "avant garde" is about a critical relationship between an artist, the making of art and how the work of art is seen.

This is where the art world splits into two factions. One side is all about beauty and truth. Art should be about craft skills and the search for an honest expression of noble ideals. The other side wants to create a critical dialogue about the very idea of making art.

For all the appeal of art as an expression of beauty, it is also a deeply conservative and culturally isolating notion.

Who gets to decide what is beautiful and what isn't? Who are these arbiters of taste and value? And is what we call beautiful the same for other cultures?

The problem for the other side is that being a commentator on the making of culture is beset by painful ironies and compromises when cutting-edge art winds up in the hands of wealthy collectors or in a stuffy museum.

Is it even possible to criticise culture when you're right in the middle of it?

A friend of mine hates the word "negotiate" when it is used in the context of artists, as in "Joe Blow's art work negotiates the terrain between memory and subjectivity . . . "

What do they do, my friend demands, are they hostage negotiators?

In a way, artists are negotiators, working out how to express themselves in the fraught and complicated battlefield of culture.

Artists want to be free to do what they want to do, while the public demands art that does not violate their expectations. Artists negotiate that difficult path. That's what artists are for.