Alex Massie is right to say that most people believe "we're governed by crooks and knaves and fools." He doesn't, however, stress sufficiently that most people are wrong.

First, such an opinion lacks perspective. There's no evidence that UK MPs are especially corrupt by international standards, or even by historical ones; I doubt our parliamentarians are gadding around town with gangsters as Boothby and Driberg did with the Kray twins. And the "expenses scandal" probably tells us more about the power of peer effects than it does about massive corruption. Only the most sanctimonious little pricks could really get angry about it.

Secondly, this view ascribes too much agency to MPs. Just as Marx claimed that the logic of their situation required capitalists to act badly whatever their own morality, so too do situational pressures bear upon MPs. I mean this in at least three ways:

- MPs must - at least sometimes - do what the public want. Some of their nastiest actions, such as the harrassing of immigrants and attacks on welfare recipients, are supported by the - albeit ill-informed - public. As Bill Stone once said, "There's plenty of cunts in t'country, and they deserve some representation."

- Politicians naturally kow-tow to big business simply because the latter offer jobs, and can therefore extract favours.

- Ministers are vulnerable to pressure from inside interests. They have the police and security services constantly yapping in their ears. And guess what, coppers and spooks rarely want to expand our freedoms.

In these senses, the belief that MPs are crooks and knaves disguises a nastier truth - that social structures condition them to behave so.

Indeed, one could argue that, insofar as politicians do have agency, the problem isn't that they are knaves, but that they are not knavish enough. In my (very limited) personal experience, MPs seem like nice people. But the thing about agreeable people is that they can agree with the wrong folk; this, I fear, was the tragedy (in the original sense) of David Miliband. My fear is not so much that politicians lie, but that they might actually believe what they say.

What's more, politics is not always a nice business. Getting your way in the face of opposition sometimes requires more than the exercise of sweet reason - in fact, in often does, given the latter's impotence. It needs the use of underhand methods too. Under the "nice" JFK, the Civil Rights Bill was going nowhere. It was only when the less decent LBJ took over and used what Robert Caro calls "savage, vicious" methods that blacks achieved legal equality.

There's a place for knaves in politics.