How many of you saw James Purnell's cringe-inducing performance on Newsnight on Monday night? He spent the first few minutes of the live interview repeatedly rebuking Kirsty Wark for focusing her questions on his resignation from the Cabinet and not on issues of substance. But when Wark finally got round to asking him which specific policies he would advocate Labour adopting to avoid "annihilation" (her word, not mine) at the next election, this was his answer:

"I think what we need to do is to renew ourselves and I think that goes through idealism. I think it goes through going back to our basic principles and articulating them for today."

Sorry, what on earth does that mean? And why does this man think he can launch a philosophical debate about the future of the left on the basis of such vague and dubious generalisations? In fact, this statement from Purnell is so meaningless, so pointless, so hollow and empty, that I would argue a whole host of figures on the left - from Gordon Brown to Tony Benn to Hugo Chavez - and perhaps even a few on the right, could easily sign up to it. So what purpose does it serve?

Where, I wondered, as I watched the interview, were his policies? What did he think should be done about Trident? Or ID cards? Spending cuts? Perhaps I nodded off on my couch, but I don't remember hearing Purnell outline a single policy or proposal that he believed would help Labour avoid the electoral defeat next year that Wark referred to in her original question.

Should I be surprised? He may be clever but James Purnell is, by no stretch of the imagination, a public intellectual, or Labour's 21st century Antony Crosland - no matter what his supporters in the press might claim. I'm not normally someone who agrees with Rod Liddle, but I couldn't help but nod furiously as I read the former Today Programme editor's description of the former Work and Pensions Secretary in a recent Speccie piece:

"He is a public school-educated monkey whose career, prior to him becoming a useless MP, comprised various vapid and pointless media consultancy positions, culminating in him being appointed to the job of lickspittle to the BBC's worst-ever director-general, John Birt, in the BBC's most useless and counter-productive and overpaid department, corporate affairs. Later, as an MP, he was the most avid supporter of Lord Hutton's whitewashed inquiry into the death of the scientist Dr David Kelly, and the most vociferous critic of his previous employers, the BBC."

To be fair to Purnell, the problem is not him. The problem is that it is now fashionable for ambitious young politicians on the left and centre-left to engage in pompous, pretentious, highfalutin rhetoric about choice, diversity, opportunity, equality and other high-minded principles at the expense of proper discussions about practical policies.

The latest buzzword is "capability", as in Amartya Sen's "equality of capabilities" - cited by, among others, Purnell in the Newsnight interview, Chief Secretary to the Treasury Liam Byrne, Foreign Secretary David Miliband and numerous other New Labour figures. It sounds fantastically deep and noble - and comes with a Nobel Laureate attached to it! - but as the Fabians' Sunder Katwala points out, what happened to old-fashioned equality-related issues like income and wealth? No longer fashionable? Out of date?

I, for one, want to know where the Labour's various self-appointed leaders, thinkers, intellectuals, etc, be they Purnell, Miliband, Balls, Cruddas, whoever, stand on specific issues like the 50p top rate of tax, bankers' bonuses, the war in Afghanistan and a whole range of other pressing, everyday issues. Hiding behind vague and vacuous clichés and catchphrases will not do.