Garvan Walshe is a former National and International Security Policy Adviser to the Conservative Party.

We don’t yet know who trained the man who shot an audience member an event discussing free speech and a volunteer guarding a synagogue in Denmark where a girl’s bat-mitzvah was being celebrated, but it appears likely that someone taught him how to kill. Someone else provided a get-away car, and perhaps another the gun.

Less glamorous, from the terrorist’s point of view, than a “spectacular” bomb, such an attack is much harder for the security forces to detect. The profile of activities involved, acquiring a stolen car and a gun, resembles non-political organised crime, of which there is far more and of which the killer, Omar El-Hussain, had a history known to police. It is harder still in the United States, where guns are easy to come by (and an atheist extremist – not, it would appear so far, part of an organised group – killed three Muslims in the university town of Chapel Hill, North Carolina last week).

As is becoming all-too-common, the targets were chosen, like Hanns-Martin Schleyer (kidnapped and murdered by the Red Army Faction) because they were symbols. The RAF could not have hoped to eliminate all German capitalists, but killing one raises the question in people’s minds whether more might be next. We find it hard to resist the habit of looking for meaning that isn’t there, and look for reasons to explain why, for instance, Schleyer was targeted. This produces two insidious lines of argument. The first is to blame not the victim himself (for nobody admits to being quite so crude) but people who might share some characteristic with the victim. Not this businessman of course, but some other one, who is capitalism’s unacceptable face. Not the Jews in the kosher supermarket or Copenhagen synagogue but other Jews, perhaps those in the Israeli government. If this is too easy to see through, it can be suggested that the victims, while personally innocent, nevertheless make the rest of us unsafe. They ought, as they draw their cartoons, take care not to be provocative because in doing so, they don’t only endanger themselves, but also the rest of us.

This is particularly invidious because it is the gunman who sets the terms of the capitulation. He decides, like the rapist who claims his victim dressed too scantily, what is should count as “provocative,” whether it be cartoons of Mohammed, or being Muslim in North Carolina.

Both attempts: blaming the victim, or questioning whether they should really be entitled to the protection of the law, are attacks on democratic governments, whose job it is to protect the people they rule over from criminals who would threaten them or murder them.

The cause for which the terrorists claim to kill (and, which is not the same thing, the cause for which they actually kill) is relevant to people who study them professionally: the academics, social workers, probation officers, policemen and intelligence operatives whose business it is to know this detail. It will obviously be important to devising strategies to dissuade and confront them. But it is not relevant to whether we decide to confront them in the first place any more than the results of investigations into why some men rape should prevent us prosecuting and punishing rapists.

That terrorists kill for political reasons sows confusion among people who share their enemies, be they the state of Israel, irreverent cartoonists or Islamic extremists. It leads them to excuse crimes they shouldn’t. But government’s first duty is to defend the rule of law against all comers without exception and without compromise. People usually have reasons why they kill, and it can be useful to find out what they are. They should never be confused with excuses or justifications.