All professions - yes, even economists - tend to have a biased perspective on the world; the French call this deformation professionnelle. Reading Theresa May's proposals to combat Muslim "radicalization" reminded me that politicians are prone to such biases too.

I say this because they are selected to have certain dispositions. It costs time and money to enter politics, and success does not necessarily go to the most meritorious. This means that politicians, even more than others, will tend to be over-optimistic. Also, you tend to enter politics if you think policy can make a difference. This tends (there are exceptions) to select against those with an Oakeshottian conservative disposition, who believe that bounded rationality plus the innate imperfections of human nature mean that some social evils cannot be eradicated.

There's a third selection effect. Politicians are selected for their emphasis upon rhetoric and persuasion. Many would-be pols were active in the Oxford Union. But if you emphasize some things, you naturally de-emphasize others. And one of these other things might be the dull grunt work of day-to-day policy implementation; the soaring rhetoric of Winston Churchill excites more admiration among politicians than the quiet administrative ability of Stafford Cripps or Norman Fowler.

This is where Ms May comes in. These raise some obvious questions: do we really want to keep potential terrorists in the UK where they can cause trouble here rather than let them kill themselves in Syria? If the security services devote resources to people plotting terrorism overseas mightn't they be distracted from those plotting terrorism here? Might a clampdown on "radicalism" reinforce some Muslims' perceptions that the west is at war with Islam and so encourage some hotheads into terrorism? Wouldn't such actions suggest to some that the "western value" of free speech is mere hypocrisy, thus further antagonizing some Muslims? (Nelson Jones has likened May's proposals to the Six Acts).

Now, like pretty much everyone else who bloviates upon these issues, I don't know how strong these objections are. But I do know that revenge effects are common in the social sciences. And I fear that politicians might be underweighting them because of their deformation professionnelle.

I stress that I'm not making a partisan point here. One thing for which this goverment deserves more credit than it gets is a lack of the legislative hyper-activism of the New Labour years. And Npower's claim that it hasn't cut gas prices for fear of a price freeze under a Labour government is - if true - an example of how Labour has under-estimated the power of revenge effects.

However, it's not just politicians who should be blamed here. So too should be voters (and the media). The tendency to regard politics in the spirit of partisans cheering for one side or another distracts us from some fundamental questions, such as: what can politicions actually achieve?