Let's see the facts.
Murder and forcing a living beeing to something against their will is always wrong.
Self defense is something a bit tricky. Lethal self defense should only be done, when there is no other choise. So if you have to save your own right without no other way to avoid your own dead.
The raiders, well they are simulated living beeings. I consider their mental state as highly ill. They are drug-addicted in a very strong way and very dangerous. Letting them run around freely is danger for other simulated persons in Fallout 4.
My normal reaction would be, that it is nessesary to protect others from them, but when they are defensless, they should be consideres as such and should get as much aid as possible, by simultaneously protect the surounding from them.
I personally believe, that a living feeling beeing should be threated with respect and not be enslaved by somebody else.
(By pets its something different. If you have a dog or a cat and the pet is allowed to run around freely and return, what normaly happens, it is not slavery or against their will. Its their free will.)
My result for Fallout 4 is:
I mentioned living feeling beeings. The raider and everybody else is only simulated in Fallout 4. It isn't even a PC sitting behind them and controlling them. So if you shoot them, if you enslave them, or something else, you won't hurt any feeling, living body. You would only play around with a situation. Because of this, i don't see any reason to act respectful towards them. One of the reason i will have my fun with the second DLC. Aswell with the first one, when i build robots. Hope they will be able to fight in the arena aswell.