Terrorism is self-evident by its means. But as with the investigations into Fort Hood gunman Maj Hasan’s contacts with a cleric linked to al-Qa’ida, we increasingly see the term narrowed to mean acts committed for a particluar end, a weasel use of the word.

Such inquiries wrongly conflate the word “terror” with a very specific form of Islamic extremism, and assume that its use is indicated if and only if such a link is found.

While not clearly defined, the word terrorism describes a particular lethal strategy. Blowing up a bus to terrify the populace is clearly terrorism, a battlefield skirmish between professional combatants, while also horrific, is not terrorism. And there is grey in between.

But what does not define terrorism is its motivation. If pro-democracy activists blow up a bus, they become terrorists. Similarly, however we feel about religious extremism, every military act initiated by such people is not automatically terrorism.

Whether Hasan’s actions, or anyone else’s, were terrorist or not does not depend on whom he sent emails to beforehand. The cause of an action and its results are ethically disjoint – the former may aggravate or mitigate, but we forgive or punish only the latter. Misusing the word terror, deliberately or not, blurs this vital distinction, and may lead us to punish the innocent and exonerate the guilty.