Many of the most common arguments against Labour's policies are laughably bad - such as the claim that people earning a little over £80,000 a year will have to pay very much more tax; or the idea that higher top taxes wreck the economy; or the demand that individual spending plans be fully costed; or the notion that nationalization is a cost to the Exchequer.

In pointing this out, however, people like me are missing something important - that even lousy arguments have the power to persuade.

Robert Cialdini gives us an example of this in Influence. He tells of an experiment in which a woman tries to jump queues to use a photocopier in a university library. When she merely asked to jump in, 60% of people in the queue complied. But the question "May I use the Xerox machine because I have to make some copies?" got 93% to agree. Even a meaningless remark (why else would you want to use the copier?) elicited compliance.

What's going on here is that the mere act of speaking has persuasive power. This has been corroborated by experiments (pdf) by Justin Rao and James Andreoni. They got people to play a dictator game in which one subject was given $10 and then invited to share some or none with somebody else. They found that in the straightforward game, dictators have an average of $1.53. However, when the third party asked for a share of the money, the dictator gave an average of $2.40. The actual wording of the requests didn't seem to much matter. But say Andreoni and Rao, "the existence of a request matters tremendously." They say:

Communication, especially the power of asking, greatly influences feelings of empathy and pro-social behavior.

The mere existence of messages, then, gets us to sympathize with the sender.

In this context, there's a massive bias in the media. People earning over £80,000 might be only 5% of the population, but they account for much more than 5% of communication. This leads us to sympathize with them. Add in the fact that people tend to believe lies, and we get a big bias towards the rich.

It's often said that many people oppose higher taxes on top earners because they hope (mostly wrongly) to become one themselves. But this is only part of the story. We sympathize with the rich not (just) because we hope to become rich ourselves, but because we hear so damned much from them.

There's a nasty flipside to this. If we don't hear from people, we tend not to sympathize with them. Separate experiments by Agne Kajackaite has shown this. She got people to work where the rewards went not just to them but to a bad cause (the NRA). She found that when people chose not to know whether the money was donated to that cause, they behaved more selfishly; they worked harder to make money for themselves. "Ignorant agents behave in a more selfish way" she concludes.

Thigh might well have political effects. Because the worst-off have less voice, we are relatively ignorant of their suffering and so less sympathetic to them. Support for benefit cuts isn't based solely upon outright untruths, but upon a lack of sympathy for them caused by their relative lack of voice.

Most of us, I guess, can name far more people who are in the top 5% of the income distribution than in the bottom 5%. This introduces a bias towards the rich.

My point here is that the media's bias isn't merely conscious and deliberate. There are more subtle ways in which it serves the interests of the well-off.