Kenan Malik: I despise him, but that's no reason to ban him

I despise Geert Wilders. I loathe his populist anti-immigration rhetoric. I despair of his tirades against Muslims. I find his film obnoxious.

But I also think that he has every right to be as crude and as loathsome as he wants to be. He should be free to be as rude about me and my beliefs – indeed, about anybody's beliefs – as I am about him and his. That is the essence of robust political debate in a plural society.

When he was banned from Britain last year, the then Home Secretary Jacqui Smith claimed that his "statements about Muslims ... would threaten community harmony and therefore public security in the UK".

Wilders is a threat to public security only insofar as some of his critics may be provoked to respond with violence. But then they, not Wilders, should be held responsible. What of the threat to "community harmony"? Wilder's ideas have caused controversy because there is a real debate in Western societies about Islam and about the relationship between Muslims and non-Muslims. That is why his party, the PVV, made gains in Dutch elections last week. However deplorable we might find Wilders' arguments we cannot wish them away. They have to be engaged with, openly and robustly.

Underlying the argument for censoring people like Wilders is the belief that, in a plural society, speech necessarily has to be less free. "If people are to occupy the same political space without conflict", the sociologist Tariq Modood suggests, "they have mutually to limit the extent to which they subject each others' fundamental beliefs to criticism."

No they don't. It is precisely because we live in a plural society that expression needs to be as free as possible. In a society in which different beliefs are deeply held, clashes are unavoidable. A society in which no offence is given or taken is one that is culturally and politically dead. The right, even of bigots, to "subject each others' fundamental beliefs to criticism" – and indeed to be abusive about them – is the bedrock of an open, diverse society.

Kenan Malik is senior visiting fellow at the department of political, international and policy studies at the University of Surrey