How much simpler it is when art comes with an instruction sheet. Pretty much everything does in "do it 2013", a centrepiece for the Manchester International Festival this year. Indeed, in quite a lot of cases the art consists of nothing but an instruction sheet. One work, for instance, consists of a notice instructing you that only visitors humming a tune will be allowed through a set of doors guarded by a uniformed attendant. Another, by the sculptor Louise Bourgeois, instructs you to go out and smile at a complete stranger, the additional instruction "Stop" adding an extra level of difficulty to the mission. A quick beam is one thing. A static grin takes you into quite different social territory.

Visiting the exhibition with the historian Tom Holland I tweeted a picture of him providing the vital spark for a piece by Andreas Slominski, which consists of an upward-tilted bicycle seat which visitors are invited to use to juice lemons. There's a bucket full of lemon halves and a bucket for the emptied rinds but no receptacle for the juice, which spreads and splashes around the plinth as the day unfolds. We would be discussing this and other pieces on the radio later that week, I pointed out. In the spirit of the exhibition I should probably have instructed people to listen, but I thought of that too late. And in any case I think there would have been resistance. "What a fine reason to rearrange my sock drawer – in silence," one follower replied, adding the hashtag #pretentiousegocentricbollox in case he hadn't made himself clear.

It was a prejudiced reaction but not an entirely illegitimate one, I felt. Because, as in all contemporary art shows – and particularly those of a conceptual bent – one instruction was missing from every piece present. How seriously were we meant to take them? And that angry tweet addressed a kind of un-instructed obedience that we all too often display in an art gallery, which is to take things seriously by default, and only rarely question the point at which an artistic conceit has tripped over into the unartistic kind.

Slominski himself seems interested in this boundary; one of his previous works consisted of inviting people to an outdoor event in Frankfurt at which there was no art at all, just the artist hiding in a nearby bush. It was the conceptual equivalent of a self-contradicting statement – only really art if there was no art there...though if the piece satisfied its own conditions there would be of course, furtively.

I think that instinctive submissiveness of modern gallery-goers is a problem for modern art. And it's not that there are things admitted into art galleries that shouldn't be called art at all, which is the reflex reaction of the more conservative consumer. Arguing about what is and isn't art is a cul-de-sac. The significant and interesting argument is whether a piece is any good as art. But it's much harder to have that discussion candidly and directly when deference is the standard mode. Attentiveness, yes – perhaps a little patience too, given that the best art doesn't reveal itself immediately – but not the quite widespread reflex to identify a disappointing experience in an art gallery as a failure of grasp.

Shortly after I'd visited "do it 2013" I read that Grayson Perry was going to deliver this year's Reith Lectures, reflecting on "the idea of quality and how we might, in an age where we are told anything can be art, appreciate which art is any good". It's an excellent subject and an overdue debate. I hope he addresses the problems that unearned respect brings with it.

All the world's a stage... well, nearly

I'm not entirely convinced by the Globe Theatre's proposal to stage Shakespeare's three Henry VI plays at four historic battle sites this summer. I suppose there will be a certain kind of frisson in seeing them at Towton, site of the bloodiest battle ever fought on British soil. But I'd worry a little about the actors getting lost in all that space. Stage war can never be a Cinemascope affair. It requires close-ups, and the tighter the frame the better view you get. In his Macbeth in Manchester last week Kenneth Branagh (above) staged a battle in a space not 12ft across and you could see sparks fly as swords clashed. I doubt location fighting can top it.

Canned? Don't make me laugh

It's probably not a distinction that audiences much care about, but the difference between "canned laughter" and "studio laughter" is very important to professional comedy writers. Graham Linehan for instance, who vented his irritation on Twitter this week at those who used the wrong term about Count Arthur Strong. Why do they mind? Because "canned laughter" is comedy fraud, pasted on after the event to patch holes in the hilarity. "Studio laughter" is the authentic response of real humans who were present at the filming. One is non-dairy aerosol cream. The other has actually emerged from a herd. And if the studio audience has too good a time, it's not unknown for them to turn the yocks down in the final mix.