Definition of Terrorism
The difference between a terrorist act and a military act is the same as the difference between punitive and preventative sanctions. A terrorist act makes no sense in terms of projecting power except when taking into account the reaction of the terrorized. A military act projects power without regard to the reaction of the targets. Terrorism is a PR campaign that incorporates punitive¹ violence against its audience.
Some illustrations: Chechens massacre elementary school children. The Chechen soldiers expended in the mission were no doubt more valuable as strategic assets then the children they massacred. Therefore this incident is terrorism because it would make no sense except as influencing the decisions of the Russians. Aerial bombing: If the resources expended in the effort are justified purely by the destruction of the opposition’s ability to make violence (and not their will to make such violence) then it is not terrorism. If the resources expended require both the direct destruction of opponent’s abilities and inhibition of their will to be justified, then it is terrorism.
Nine eleven: terrorism because the attackers wished to send a message rather then incapacitate America, it is terrorism. The Cole attack was a legitimate military operation since military casualties inflicted by the radicals partially incapacitated the US’s ability to project its power in the middle east. Sure it was covert and irregular, but then again, so are US special forces. Killing the innocent close family of a judge is clearly an attempt to influence that official and therefore terrorism. Assassination is separate from terrorism and well defined.
We don’t approve of terrorism or torture in modern society for the same reasons. Both attempt to force others to carry out one’s own will. We currently prevent criminals from carrying out further crimes by isolating them from society. We used to simply lock people in the pillory and torment them (often to the point of maiming) for a few hours rather then isolate them from society. The purpose was to create a disincentive to crime through punitive measures, as opposed to inhibiting the criminal’s ability to do crime through imprisonment.
By extension then, the set of terrorists is a subset of propagandists. A military may engage in propaganda, but not all of its soldiers are propagandists.
¹: I specify punitive. I guess there could be a “Get punched in the face by a Gangsta Rappa” raffle as promotion for a consumer product. This does not qualify as terrorism due to the fact that the violence is viewed as desirable by the audience (people who want to get punched in the face by a rapper).