"The Shooter" is a stranger that walks around and shoots everywhere. He is likely to have two handguns, or a rifle or a shotgun. He is not hiding.
"You" are someone who is hiding behind some furniture and shooting a handgun at the shooter.
If the difference between the two is not obvious, don't shoot. This rule always applies: "Be sure of your target and what is in front of and beyond your target."
If the incident happens in an office or any place where people know each other (like maybe a smaller church) then chances of misidentification are even smaller.
But if despite all of that your 3rd person makes a judgement mistake and tries to shoot you ... well, chances of that are still lower than chances of a determined madman to eventually find you and kill you. There is no guaranteed way to walk out of such situation; you can only talk about probabilities. If none of the victims are armed then their probability of survival is about zero. Anything that improves that is a plus.
All of what you say makes perfect sense, and it is logical. And I’d even agree with the correctness of the theory.
But it all still relies on alot of assumption: for example, it assumes that everybody who is packing heat is operating in a rational fashion and has the mental presence to think things thru (”do I know that person?” or “who’s behind the shooter?” or “Is Mary-Anne the shooter? Has she flipped out?”).
Actually that last one is a biggie: you’ve assumed that the shooter is someone unknown to everybody else. That wouldn’t have been true in the Virginia Tech case. Who’s to say the shooter isn’t your best mate that you’ve worked with for 20 years?
Please don’t misinterpret me: I believe in your right to keep and bear arms, and I sure wish I had that right here, where I live in NZ.
I do think it is an assumption, tho’, that having everybody armed all the time would necessarily do much to avoid incidents like what happened in New York last week. Or even reduce the body count by much. I don’t know whether it would or it wouldn’t: it’s an untested assumption.
And you know what they say about Assumptions being the Mother of All Stuff-Ups...
That is the bottom line that can't be changed by anything a human being can do. It can't be changed by laws. It can't be changed by being armed or being highly trained. It can't be changed by a police state government. It can't be changed by metal detectors or lead-lined safe rooms.
The possible outcomes are nearly endless and there simply are no guarantees no matter what preventative measures are taken.