Howard Jacobson: The rest of us could do with some of Boris Johnson's chicken feed

Money talks. In fact money is never quiet. It's had a lot to say for itself this week in particular, just when you might have thought it would have the nous to crawl into a corner and shut up. But that's the way of it with money. It isn't only garrulous, it's indiscreet.

The banker's bonus is back, in so far as it ever went away, to vex our quiet. It was the banker's bonus that fuelled our orgy of rage against MPs and their expenses last month. I don't say politicians weren't culpable in their own right, but we confused small offences with major ones, fumed over hairdryers and hand towels as well as moats and mortgages that weren't, because the banker's bonus had exposed the vast inequities at the heart of our society, and while we can't get at bankers we can get at MPs.

What the bonus taker can't understand is our objection to him, and what we can't understand is why, if one has a salary, one has to have a bonus – beyond 50 quid and a bottle of bubbly at Christmas – to boot. To be paid extra because you do your job well presupposes that your pre-bonus salary is paid to you for doing it indifferently. This is not a logic you can expect a nurse or a schoolteacher, a policeman or a fireman – that's to say the people to whom society is truly beholden – to comprehend. How does one measure a nurse's bonus? By the amount of mortality she oversees? And a schoolteacher's by the number of loutish pupils he manages to get away with clobbering?

It was also disclosed last week that the director-general of the BBC, Mark Thompson, earns, what with one thing and another (and if it isn't one thing it's another), in excess of £800,000. Why? I don't mean why was it exposed, I mean why does he earn it? By what system of computation is he deemed worthy of the salary of 20 firemen, or 25 teachers, or I don't know how many jobbing media men like himself? Leave aside how good he is at what he does, for we must leave aside how good the fireman is – though if Thompson were exceptional then what the corporation produces would be exceptional, a credit to the vitality of the nation, and it isn't – but leaving that, I say, aside, why do we pay a public servant such an obscenely excessive amount of money?

Because otherwise he will go somewhere else? Then let him. If he stays only because we pay him what would otherwise buy us a small hospital, what does it say about his commitment to the moral and intellectual challenges of the job? A man should be proud to be director-general of the BBC, at a quarter of that salary, and if he isn't then his valuations of both himself and his profession are awry and we don't want him in so sensitive and influential a position.

It is, I know, impossible to measure worth of job against worth of job. But if our object is a fair society, we have to say that some inequalities we will not tolerate. And one man earning – earning? – the salary of 25 is one of them.

Nothing much we can do, I know, when that man has built his own business and taken his own risks. In a market economy, profits justify themselves. Ditto the earnings of stars in that lowly firmament of time-wasting we call entertainment – footballers, rappers, telly presenters. Though here again I would argue that the vast discrepancies between their earnings and that of those whose time they waste do not make for a calm or kind society. If acts of violence are more often than not the consequence of a violent upbringing, then theft and robbery are no less the consequence of a consciousness of worthlessness and dispossession. And whoever takes from our sense of remunerative self-esteem dispossesses us.

Am I saying, then, that it was Ronaldo's 30,000 smackers for every missed penalty (or Jonathan Ross's for every misplaced prank) that persuaded our MPs they were within their rights to nick an extra coat hanger at the taxpayer's expense? I wasn't in fact quite saying that, but now I hear the argument advanced I am convinced by it.

Boris Johnson, with his usual boastful carelessness, contributed to the nation's sense of dispossession in an interview for the BBC's HardTalk the other day. "'Chicken feed," he called the £250,000 a year he gets for writing a newspaper column. There is not room on this page to count the number of ways in which that throwaway line is fatuous, distasteful, contemptuous and cruel. He is the Mayor of London, among other things, for which he is also paid what he would no doubt consider chicken feed, and as the Mayor of London should a) be aware of the financial hardships faced by many of those he represents, and b) know not to trumpet his easily obtained wealth in their faces.

Too late for the speed of his mouth – for the tongue of a conceited man works faster than a skink's – the Mayor realised his gaffe and explained that he was only joking. But there is no such thing as "only joking". Our souls speak through our jokes, unless we have no souls in which event it is our unconscious that does the talking. If Boris Johnson made a joke to the effect that he looks down on the poor and the illiterate from a shonky eminence of extreme good fortune, it is because that is precisely what he does.

Everything he said thereafter, in extenuation of his little joke, only made him more of a chump. He thought it "wholly reasonable", he said, to write newspaper columns on the side because he writes "extremely fast". Much in the same way, therefore, as he thinks and speaks. "I don't see why, on a Sunday morning," he went on, "I shouldn't knock off an article. If someone wants to pay me for that article, then that's their lookout."

What self-respecting columnist describes his work as "knocking off"? What regard for the poor suckers who read those columns does that display? A good column will be brooded on for half a week and takes at least a day to write. As for its being the "lookout" of those willing to buy whatever he knocks off on a Sunday morning (when he ought to be in church, confessing), what morality of fair exchange of salary for honest labour does that suggest?

Thus, unashamedly avowing shoddiness here and cynical opportunism there, the Mayor of London exemplifies our times. Only fools and money talk.