Thanks for the thoughtful answer. I understand your point about escaping P.O.W.’s. I presume that Geneva Convention and military regulations apply in such circumstances. I have to believe you are not saying that a civilian hostage could not kill a terrorist in order to escape, for example. Let’s say, then, the civilian was not a hostage per se, but was just plucked off the street to serve as a houseboy in the local mosque. I’d say he had the right to kill anyone who stood between him and freedom.
I believe we are in agreement. In modern military terms, it is conditional on two events, first surrender and second, control.
An individual that is continuing to resist and has not surrendered to a military can be killed on the spot. A person who has surrendered has exchanged their freedom under terms of treaty so that they might live. As such, under law, they have to abide but such laws. There is a grey area, that is covered but the rules of “control”. That grey area is when someone wishes to continue to resist but is unable to. This can be from either not having the means to resist, (out of war supplies) or physically unable to resist as in wounded.
The rule of control can be summarized as a situation where a soldier has been placed under the control of the opposing military. Meaning that a formal surrender is not required. This allows the victor to go into a hospital and take control of all wounded personnel as if they had surrendered because they are no longer physically able to resist.
As for the Terrorist scenario that you present, a terrorist is not operating under the rule of law. As such, they are conducting criminal activities and threatening the life of the individual. At that point in time, the right of self defense applies and the hostage has the right to use what ever force is available to them to remove themselves from the life threatening situation.