Howard Jacobson: Why mock the expectation of beauty in art? It is laudable that we want to be impressed

A Pissarro or a Pissoir is our theme for today. But first, by way of fortifying our intelligences, the example of Dr Johnson "rejoicing to concur with the common reader" in the matter of that much loved poem "Gray's Elegy" – "for by the common sense of readers, uncorrupted by literary prejudices, after all the refinements of subtility and the dogmatism of learning, must be finally decided all claim to poetical honours".

When it comes to judging literature we cannot manage without recourse to that "common reader". Whether he ever existed in actuality is hard to say, but he is certainly not conspicuous today. Take a look at the literary blogosphere when you have nothing better to do, or the windows of any bookshop, and you will see to what depths of intellectual ignominy common readership has sunk. But we more than ever need the concept. Beyond the prejudices of special interests and the over-subtlising of the literary profession speaking only to itself must be a bar of common judgement – real or imaginary – before which all productions have ultimately to appear. It is for the common reader, philosophically conceived, that a writer writes.

As it is for the common viewer, looker, observer (interesting how hard it is to find the word, other than dealer, buyer or curator) that a painter paints or an installationist installs. Except that it isn't. Duchamp saw to that. Paradoxical to say such a thing, I know, given the avowed democracy of Duchamp's intentions, presently arrayed in all their mischievousness at Tate Modern, but paradox or not, it was Duchamp who, in the very process of debunking the authority of the gallery and the grandee, closed the doors of art to all but those who got the joke he chose to make of it.

And it's to those who don't get the joke that we wish, today, to offer support. Not as allies in incomprehension. We do, as it happens, get the joke. We don't think it's a particularly funny joke, but we get it. And that's not because we're smarter, but because we've been let in on it. We've read the explanatory essays. We've served the time. We've met, in our line of work, comparable jokers. We don't, however, see why everyone should have to labour likewise, or rather, we don't accept the pretence that there's no labouring to do – that if they only trusted their native innocence, Joe and Josephina Public would get all there is to get.

This is the big lie of contemporary art: not nothing being passed off as something, but the make-believe that the division between high and low has been destroyed and that we're all now capable of being artists or art-consumers once we rid ourselves of false bourgeois assumptions about what art is.

In this I beg to differ from my fellow columnist Philip Hensher who wrote enthusiastically about Duchamp in this newspaper the other day. Addressing what he calls "the philistine response" of those who object to Duchamp's urinal or similar found-object on the grounds that they too could find a thing and put it in an art gallery, Philip Hensher invokes Beuys whose answer, he says, was always, "Of course you could; why on earth do you believe the creation of art to be something beyond your capacities? Who taught you that?"

In fact, it's no mystery who or what taught them that. Previous visits to art galleries taught them that. The cathedral at Orvieto or the Sistine Chapel taught them that. An expectation of beauty, or excellence, or difficulty overcome, taught them that. I see no reason to mock such an expectation. It is laudable that people want to be impressed. Admiring what we cannot ourselves do is a mark of generosity of mind. It is in order to enthuse over what is beyond our capabilities that we travel, read, look, listen, even go to restaurants. It is not philistine to be moved by art whose execution astounds us.

Things have trundled on in the art world, it is true, since beauty was the criterion. And while we might choose to stay with beauty if we so desire, we are without doubt naive – naive, not philistine: for the two are not the same – to be unaware that contemporary art is, ideationally, somewhere else. Here is where the disingenuousness of Beuys et al comes in. When he tells the bewildered viewer of found-art that he too could find and exhibit it, he is telling an untruth. You cannot knock on the door of Tate Modern holding a twig that happens to look uncannily like Nicholas Serota and expect them to hang it.

For, as Serota himself has often cautioned us – and this is modern art having it both ways with Mr and Mrs Public – you can't just come in from the cold and hope to understand. Aesthetically speaking, a found object is much more than a found object; behind its showing lies a highly sophisticated philosophical justification for its showing, a strategy of subversion, displacement and surprise entailing enough exegesis to keep 1,000 curators busy 24 hours a day.

Beuys is right that anyone can be artist enough to find a found object, but to know why you are finding it and by what alchemical process of politics and irony it becomes art you have first to put yourself to school to conceptualism and its allied theories, which might be beyond your capacities or your patience.

To those who would rather look at a Pissarro than a Pissoir I say you are right, in so far as it is plenty to which you want to treat your eyes. But sensuality is out of fashion. The puritanical abstemiousness of post-Duchampianism rules now and you should find out what it is about. As things stand, it is your outrage and incomprehension that go on giving this art its raison d'être.

Go to Tate Modern. Get to the bottom of this. Don't let the jeerers take advantage of what you don't know. Don't stumble exactly where they want you to stumble by saying you can do what you will now discover you cannot. You probably have too much heat in you to want to anyway. But that apart, it is time you stopped being their fall guy.

Look at what's on the walls, read the notes, don't go blundering into any of that "a child could do this" nonsense ever again. Grasp that the strategy is now the art, and that while the art might be nothing the strategy is smart. Learn to juggle absence and presence. In French, preferably. Admit the icy ironies. Even laugh a little. Then get back to enjoying your Pissarros.