We should have argued Sweden Democrats to oblivion

What surprises me most after the Swedish elections is that so many people seem surprised the ultraconservative Sweden Democrats party (SD) has made it into parliament. From no representation it now has nearly 6% of the vote, which means that it will get 20 MPs; it also destroys the previous centre-right majority and creates an uncertain situation in parliament. Sweden will get a weak government, one that must rest on different minorities, since all the parties have spent most of the post-election debate guaranteeing that they won't in any way co-operate with the SD.

This went so far on election night that the leader of the Left party, Lars Ohly, refused to have his makeup done at the same time as Jimmie Åkesson, the SD leader. That was silly, of course, even if you understand it. But every time anyone from the SD is shunned like that it can have little effect except to make more people sympathise with them.

Three questions are important: who are the more than 300,000 Swedes (out of a population of 9 million) who voted for the SD? Why couldn't this be stopped? And what must be done about the result? We still don't know in detail who voted for the SD. But we know some things. Like other ultraconservative parties, the SD is also a "protest party". People vote against something rather than for it. In this case, people are looking for a scapegoat for their own miseries. It is the unemployed, the ill, those who feel themselves marginalised and cast out, who turn in their powerlessness against the established parties and vote for those who reach out to them. The SD becomes the only decency they find in a political landscape where everything else is hypocritical and forsworn. The SD listens to them. In the SD's programme they find their own thoughts, their own anger, their own fears.

It is wrong to believe the SD recruits from conservative circles. This happens, of course, but it's not the dominating factor. On the contrary, there are many studies that show the SD gets most of its recruits from the working class.

And, as I said at the beginning, only those who refused to see what was happening didn't understand the outcome. For too long during the election campaign the SD was pushed out. The other parties refused to engage in a dialogue with it. The SD was forbidden to come and spread its "message" in some schools.

This was, of course, a completely mistaken and counterproductive strategy; it was, in fact, idiocy. The only way to deal with people with racist, xenophobic and generally populist views – like the German National Socialism of the 1920s – is through a determined dialogue that we never abandon. The commandment echoes from the Enlightenment: "I disapprove of what you say, but I will defend to the death your right to say it".

I believe that it was precisely the refusal of the other parties, from left and right, to debate with the SD that allowed them to grow from nothing to 6% of the vote. If we had had the debate, the SD might have got into parliament, but with far fewer seats. In fact, they could have been kept out of parliament altogether.

So, I blame everyone who has been surprised by this result, or "saddened" as they now say. The responsibility lies with those who saw this coming but looked away. And were silent. One can never choke the voices of reaction with silence. One can only argue them to death. Above all, we must criticise the doubtful intellectuals, and the politicians who struggled to win seats and a majority for either the centre-right or socialist-green blocs, but who never debated with the SD.

Certainly, there is a rightwing wind blowing over Europe. But in Sweden we have until now been able to keep these ultraconservative groupings out of play. They have had a few representatives in local government but not much more than that. The difference this time was that the SD was much better organised, that they made their views much clearer, and that they were pushed out. At one stage a television channel refused to show their party political broadcast. It was thought too xenophobic. I don't know how many people decided at that moment to vote in protest against this censorship – which is what it was. But did the refusal to show the film give the SD more votes than the film itself would have done?

What will happen now, in the hung parliament we're going to get? No one, least of all me, is asking that we allow these anti-human politicians into the government of Sweden. But respect for the 300,000 people who voted for them demands that we accept the necessity of dialogue, before these 300,000 become two or three times as many. We're not there yet. We won't ever reach that point, either.

Henning Mankell, a Swedish crime writer, occasional children's author and dramatist, best known for a series of mystery novels starring Inspector Kurt Wallander.