This question is simple for me, I don't put my morality over survival. I even keep a sword next to my bed, in the case that an intruder comes into my living space with a weapon, they're either getting out with the cops or the paramedics.

I just don't believe someone who is willing to kill others for no reason, not even self defense, deserves the second chance sparing them would give them. When people kill and get away with it they tend to make a habit of it, would I really want to be responsible for someone else's death because I felt compassion towards a murderer, no I would not.

Edit: Forgot to mention I have also done weight lifting, so I'm not exactly weak, I've got a heavy build.

pennylessz : I think I know who my money is on if it's a hardened criminal used to breaking and entering vs. an 18 year old with an unwieldy weapon in close quarters.

Do you train with that sword extensively so you're ready to go from a dead sleep to fighting for your life against an armed assailant?

Ghostbear1111 : I keep my door blocked so if they break in the room I have time to react just in case I didn't hear them enter my apartment. 
I practiced with wooden swords crafted in a woodshop down the street for years when I was younger, I definitely know how to swing one at least.
I also am one of the only people I know who isn't drowsy after waking up, everyone I know has to sit there and get their bearings, I used to practice getting up quickly, and can get out of bed and in fighting stance in less than three seconds.
I have taken some Karate, but it wasn't for very long, I do however know the proper stance, punching, and kicking motions, and have been taught how to disarm someone with a melee weapon. (Though I'm a bit rusty on that last part).

I mostly practiced all of this because I am the guy paranoid enough to keep a sword near him, but honestly they're really around because my girlfriend moved in with them. (She really likes Japan)

If it means saving my life, someone else's that is dear to me or to prevent a mass shooting, then I think I might have that "will." I abide the non-aggression principle (do not initiate violence), so killing is legitimate self-defense is perfectly justifiable.

Hrm...you see, I don't like to think of myself as a violent person in general. When it comes down to it, in most situations, I just don't like to fight. When I get angry though, I've gone far enough that there should've been a fight, had the other person not backed down, or I myself was held back. I think that I might, but only because I wouldn't know when to stop beating on someone if I had the opportunity, not because I had any desire to truly kill. I can't say for certain whether or not I would do so, on the other hand, so...yeah. That's all I've got.

An interesting question for sure. Really made me think. 

I think the only time I would be able to have the will to kill is to protect a loved one who is unable to protect themselves, or if I had to just defend something of mine that has value to me. Other than that I think I could incapacitate somebody but never kill.

Well this is one sensible question.

Personally, I can't see myself killing anyone out of pure will. I've discussed this with a friend lots of times, he basically thinks the same. I believe we have naturally evolved as a society in such a way that we find killing pretty much anything a traumatizing thing. I dunno, I believe the only way for someone to get used with this is actually doing the deed lots of times (as in, a hit man or a serial killer, although the latter is already born with psychological issues, but I think it counts as well). I'm not a hero, no one is, so I shouldn't act like one. Except for fire fighters and the police.

However, everything has an exception. If I had to kill someone for real, I would think of three exceptions first:

* Did this person tried to attack me or one of my relatives?

* Did this person tried to steal something of value?

* Does this person threaten me to death?

If either one of these is true, I'll go ahead. It's a natural thing, we defend ourselves and what we battled for. Legitimate auto-defense. Note that I included a threat as an exception for one sole reason: would you really feel safe watching someone who is threatening you go away, free as a bird, just for him/her to appear again some time later and try to kill you in your sleep? You're defending your right to live, so I believe that's one good reason to kill someone if you really have to.

If none of these are true, then all I can do is forget about it. Because, as I said earlier, nothing beats the right to live, even though not everyone should have this right IMO, but who am I to judge. People are people.

In either case I also believe I would throw up on the ground in an instant due to being too shocked.