Aside from justified self-defense, here are some other valid reasons to hurt and kill people:
When is it ethical to humiliate, hurt, and initiate violence?
Answer: When the so-called "victim" is a consenting adult. Whether it's a movie stuntman being deliberately hit by a car or a masochist who likes being whipped and humiliated, as long as all parties involved are consenting adults, it's okay in my book.
When is it ethical to kill the innocent for money?
Answer: When they are sick and wish to die. If a person has some horrible disease and in a sober state of mind they choose to die, I think it is ethical to mercy kill that person and even charge for this service. I would prefer a waiting period of a few days to make sure the person didn't make a hasty decision in a bout of depression, but I see no reason to make someone suffer needlessly for months or years when they prefer a painless, peaceful death. I fully support euthanasia.
If the person wishing death happens to be healthy, then I am undecided. On the one hand, I think adults should have the right to do anything they want to their bodies, including self-destruction. However, there comes a point where the individual's mental health must be considered. If someone wants to blow their brains out because they lost $20 in a hand of Poker, I would physically stop such an individual if I could and give them time to think it over.
When is it ethical to rob someone at gunpoint and shoot them dead if they resist?
Answer: When they rob me first. Suppose some random hoodlum points a gun at me and demands my wallet, which I surrender immediately. He takes out the money and throws the wallet on the ground and walks away. I immediately go to my car and get a revolver. Now I am armed and I see the person who just robbed me. In his hands he's holding the cash he took out of my wallet. I have the moral right to point my gun at this person and rob him of that cash. If he draws a weapon in self-defense, I will shoot him dead and wring the wad of cash from his dead hand.
When is it ethical to torture someone?
The following are premises in my hypothetical: It is known with 100% certainty that the person in custody has planted a bomb in some public place and it will explode in a matter of hours. He gladly admits that he planted the bomb, but instead of telling us where it is, he talks about all the blood, flying body parts, and dead people his bomb will produce and the joy this will bring him.
At first I would try reasoning with him. I'd call in expert negotiators and criminal psychologists and do everything possible to get him to reveal the location of the bomb. If that failed, I would recommend drug-assisted interrogation with a military-grade truth agent such as thiopental sodium or Methylene-Dioxy-Meth-Amphetamine (MDMA). If those humane methods also failed, the only rational course of action at that point would be physical torture. Even then, I would begin with torture that would not cause permanent damage because the goal here is not to inflict injury but to motivate the individual to cooperate. Water boarding seems to cause great physical discomfort with no permanent damage so I'd begin with that. You may see a video of atheist writer Christopher Hitchens being waterboarded if you click the image below.
More Intense Torture
On a TV show about medieval torture devices used by the Spanish Inquisition, I remember hearing that no matter how principled and courageous a person was, and no matter how devoted to his religion or cause he happened to be, absolutely no one was able to withstand The Rack. The subject's feet were tied to a fixed location and the wrists were tied to a chain or rope that wrapped around a crank shaft. When the torture assistant turned the crank, the device stretched every tendon, ligament, and joint in the body, causing unbearable, excruciating agony. Essentially, the person was slowly ripped apart. While revising this device, the inventor decided to add a ratchet to the crank, allowing the stretching mechanism to be locked in place. This caused the subject to remain in the stretched position for however long the Inquisitor wanted: minutes, hours, or perhaps even overnight.
Sometimes the soon-to-be victims were in a torture queue. Those who were next saw exactly what was in store for them. Merely watching someone get the treatment and hearing their cries of anguish was enough for some people to confess on the spot. Those who thought themselves strong always confessed when it was their turn on The Rack. They confessed to crimes they did not commit, to being witches and servants of Satan, they involved innocent people in plots against The Church, etc. They agreed and confessed to absolutely anything just to stop the torture. In essence, this device was effective at breaking people, both physically and psychologically.
I would approve the use of such a device only if all previous humane methods failed but most importantly, if it is known with absolute certainty that the person being interrogated planted a live bomb in some public place so as to kill many innocent people. If there is even the slightest chance that the wrong person is in custody, then torture of any kind is immoral and not to be used.
The torture is morally justified because it is voluntary. The subject can end the torture at any time by revealing the location of the bomb.
Since it's impossible to be sure that a given individual has the information you want, my approval of torture is largely hypothetical.
In the movie "The Cell" (2000), a serial killer kidnaps a woman and puts her in a device with a timer that will kill her in several hours. If this serial killer were captured and he were conscious and able to communicate, I would approve any and all forms of torture to get him to reveal the location of the victim, so that her life could be saved.
Again, the torture is morally justified because it is voluntary. The subject can end the torture at any time by revealing the location of the victim.
