I said I'd reply to striqun's argument. It's been a rather drunken Bank Holiday weekend, but now I'm ready.

First off, can I just say what a nice change it makes to have a civilised debate? Normally I'm arguing with godbotherers, warmongers or homeopaths. How very convivial to be able to assume a certain amount on the part of the other participants. It comes as a particular relief after several weeks spent knee deep in the Qur'an. I feel almost - cleansed.

Cleansed, and baffled. For suddenly I find myself constructing an argument without needing to insult anyone, and I'm really not quite sure how to proceed. Typically my opponents come strutting up with their inerrant texts and their only too errant capitalisation, there's a brief flurry of adverbs and spite and they withdraw to pull my barbs out of their bleeding haunches and look them up in the dictionary. It's nice to swap my halberd for an armchair and a glass of something soothing, but it does leave me in need of a way to break the rhetorical ice.

Ordinarily I'd start by defining terms, but that would leave me defining art, a notoriously futile activity. As Louis Armstrong said about jazz, if you gotta ask you ain't never gonna know.

But perhaps I should bite the bullet, brave the inevitable brickbats and pick out some of the features of art which are relevant to this debate. I must emphasise though that these are neither necessary nor sufficient. In other words, you could perfectly easily have art which doesn't meet any of these conditions, and you could have artefacts which meet all of them but still aren't art.

Firstly, art is an intention rather than a thing. It's art because whoever made it says it's art. By this definition, coral reefs, though beautiful, are not art, but if I made a coral reef identical to the real thing and said it was art, it would be.

Secondly, art has stuff going on under the surface. It refers to things, including itself. Dali's droopy clocks aren't just droopy clocks, they symbolise Einsteinian time. Or something. Ovid's Metamorphoses include explicit and implicit homages to the Iliad.

Thirdly, art shows, rather than tells. Picasso's Guernica is political, but it's political art, because it isn't just an explanation of why bombing is bad. zombizi's pictures are about stuff like mortality, or human relationships in the age of the Internet, but they don't explicitly say so. He's probably a bit ticked off that I've said so, so I won't go on.

Fourthly, art has structure. Symphonies come in movements. Novels have chapters, paintings have frames. And digital images have pixels. For all the images we see on the Internet are written in 256-256-256 time. Or something similar. You get the idea.

Your homework for tonight is to think of exceptions to these rules, and add them in the comments. Tomorrow, the main argument.