I used to think I'd never hurt anyone else to protect myself; just try to immobilize them, etc.
Then when I was working in the prison system with psych patients, one of the inmates pulled a knife on me. Luckily the situation was defused without any violence or bloodshed. That incident did make me realize, however, now that it was no longer a hypothetical scenario, that I would indeed have used whatever means necessary to protect myself and the other people for whom I was responsible. I'm all in favor of the philosophy of minimum force necessary, but whatever that might have been I'd have used it. And only the situation itself can tell you what that will be.
I'm not a large person. It wouldn't be reasonable for me to assume that failing talking someone out of doing something stupid (i.e. harmful to me!) that any sort of physical force on my part would be pretty ineffective. So I go to the range and practice shooting, trying to hone my accuracy at different distances. My goal would be to incapacitate someone if necessary, but only if necessary. I wouldn't want to be fiddling around trying to figure how my gun worked in a crisis situation.
But yes, if no alternatives were possible, that experience taught me that I certainly would use whatever means were necessary to protect myself. That could potentially involve shooting someone else, as a last resort.
