When trying to be funny about the news, it's sometimes necessary to juxtapose recent events with prominent celebrities: if Age UK reports growing depression among the over-60s, the joke might be: "Why not send for Wayne Rooney – he'd cheer them up!?" In response to news that the European Union butter mountain has increased, you could say: "We should get Vanessa Feltz/Eamonn Holmes/[insert name of more topical overweight person] on to that!"

The audience will dutifully laugh, which is appropriate because these jokes are cracked out of duty rather than love. Like punning links on daytime TV, they're not put there for people to enjoy, but to demonstrate effort. I have a slight sense of humour failure about them. I don't mean that they offend me, just that my sense of humour genuinely fails to function where they're concerned.

I think: "Well, that wouldn't work. There's no way that one person, even a fat one, could make any significant dent in an entire economic community's dairy surplus by eating, if that's what you're implying. Even if they were really hungry, how much butter do you think they could realistically consume every day, assuming they were attracted by such a physically ruinous career opportunity? Maybe four pats of butter a day? Maybe five? That would be going it some and yet wouldn't be anywhere near enough. In fact, I'll go as far as to say that it would be a completely unnoticeable contribution.

"Or," I wonder, "are you suggesting that Vanessa Feltz should set about achieving the wholesale reform of the Common Agricultural Policy? That's a marginally more plausible solution, but I still fail to understand why she's likely to succeed where so many seasoned politicians have failed. What is it about her experience at BBC London that you imagine will give her the edge in playing the Brussels bureaucrats off against one another?"

This all makes me think about Data from Star Trek trying to understand comedy and I start worrying that I might be a robot.

If you were trying to teach a robot how to make jokes, this would be a good type to start with. If Captain Picard commanded Data to quip about, for instance, reports that Britain's high street retail sector is in crisis, I imagine he might, after a conscientious but instantaneous search of his memory bank of British popular culture in the early 21st century, venture: "Why not seek the help of TV's Mary Portas, from Mary Queen of Shops? Pause for amused noises."

So does the fact that David Cameron has actually done this suggest that he's now trying to make his policies funny? Or, to put it in the format of an Ed Miliband-style zinger: "Are the prime minister's policies just a bad joke?"

Of course not. David Cameron is perfectly competent at humour and would understand that Data's joke doesn't work properly because, in order to make it a dig at the celebrity and therefore potentially amusing, you need to pick someone whose weakness, not strength, is to do with shops or shopping. Elton John or the Duchess of York would probably do. Richard Madeley wouldn't, not because the shoplifting story turned out to be untrue, but because, logically, shoplifting would hinder, not help, the retail sector. Data would get that.

Nevertheless, the recruitment of Mary Portas is a depressing development. Not because she'll do any harm – I've met her and she's charming, intelligent and driven. I expect she'll do good insofar as she's given the chance to do anything at all. But I fear she'll find that, eye-catching headlines about government responding to retail problems having been garnered, ministers will consider her job to be basically done.

They're using the media's obsession with celebrity to create a simulation of action which, like a montage in a film, is much more engaging and less arduous than genuine activity.

But it reinforces the illusion that those who present things on television are at the top of the field that they're presenting something about – that Rolf Harris is the greatest artist living in Britain and Melvyn Bragg our most brilliant intellectual – rather than just people who are doing quite well in the media. Labour attempted this trick when Gordon Brown appointed Alan Sugar as his "enterprise tsar". The dispiriting Jamie's Dream School was entirely predicated on this notion.

It's government by anecdote and it changes the public's perception of what governments are for. We get distracted into thinking that politics is about ideas, innovation and "thinking outside the box", rather than seeing the mundane truth which is that it's primarily about money. Governments decide how much tax we pay and what to spend it on. They should express their values and priorities through how they take money from us and how they give it back – and that's what we should judge them on.

Politicians shrink from being judged in that way. Those on the left don't want to be associated with tax rises, those on the right want to distance themselves from spending cuts and both sides want to be insulated from the vagaries of the country's economic fortunes, unless things are going well which they usually aren't.

So they try and bamboozle us with a semblance of activity, with talk of ideas. They try to persuade us that ideas can replace money – that they can make the NHS both cheaper and better, that taxes can go down and spending up.

Well, in politics, the power of ideas is hugely overestimated compared to the power of money. "But what about the wheel, the steam engine and the microchip?" an ideas-obsessed politician might reply, "They changed everything." They did but ideas like that are incredibly rare and they're seldom the products of government thinktanks.

I'm talking about ideas like "the Big Society", PPPs, outsourcing and, of course, privatisation; supposedly the cold fusion of our public services, it has directed billions of pounds of public money into the hands of private shareholders, led to a baffling array of people knocking on the door trying to interest you in a different logo on your gas bill and produced a railway system which is the most expensive way of becoming infuriated in Europe. That's the kind of idea with which politicians try to disguise what they're actually spending or cutting.

Comedy routines need ideas. So do party conference speeches. And so, I suppose, in a Machiavellian way, do political careers. But when it comes to running the country, the less talk of ideas, of values, of emphasis, the better and more honest our government will be. It should put our money where its mouth is.