I'm pleased to see Phil McDuff joining free marketeers in complaining that anti-obesity strategies of the sort promoted by Jamie Oliver will hurt the poor. For me, though, there's a deeper and nasty question here: if we can't trust the poor to feed themselves properly, what can we trust them to do?

Yes, there are mechanisms whereby the poor might choose bad diets.

One is the fact that coping with poverty is so stressful that it depletes (pdf) cognitive bandwidth.

The other is a form of ego depletion. After a long soul-destroying day, people seek relief in drink or junk food. As James Bloodworth writes:

When we walked through the door at midnight at the end of a shift, we kicked off our boots and collapsed onto our beds with a bad of McDonalds and a can of beer. We did not - and nor have I met anyone in a similar job who behaves this way - come home and stand about in the kitchen for half an hour boiling broccoli. Regularity of dietary habit is simply incompatible with irregularity of work and income (Hired, p52)

There is, however, no reason to suppose that bad choices will be confined to diet. Quite the opposite. The poor face tight budget constraints and so have an incentive to look for the best value food, and we all know that bad diet can kill us. On both counts, they face strong incentives. Also, buying food is something we do regularly, which means we should eventually learn from experience how to do the job well. Yes, people can make mistakes. But cognitive biases apply most when we are making judgments under uncertainty: there's a clue in the title of Kahneman and Tversky's first book. But this is not the case with food: we all know what chips taste like.

If people make bad decisions about their diet, therefore, they are likely to make bad ones elsewhere. If we can't trust them with their food choices, why should we trust them to vote, given that ignorance of basic political facts is widespread?* In this sense, anti-obesity policies are a slippery slope.

But as Phil says, there is an alternative here. One way to improve people's diets is to increase their incomes so they can afford healthier food and to reduce the poverty, insecurity and bad working conditions that drive people to bad food. The problem is capitalism, not the poor.

Some of you might have an inkling as to why the millionaire Jamie Oliver and old Etonian Hugh Fearnley-Whittingstall don't choose this route. But why don't others?

Phil's right. It's partly due to classism - "a deeply rooted belief that the poor are feckless and make bad choices." Also, there's an element of what Nick Cohen called vice signalling. Governments that impose pain upon people look tough, strong and manly - even if (as in the case of benefit sanctions) those policies are counter-productive.

These, though. Are both symptoms of a deeper condition - a belief that the iron fist of the state must be used against the poor, and never against capitalism. Diet, like everything, is a class issue.

* We can't rely upon the law of large numbers to ensure that errors cancel out. The point about cognitive biases is that they are, well, biases.