You are certainly entitled to your beliefs, but I do not think that the evidence supports them; as I said before, studies I have seen do not seem to show the drawbacks greatly outweighing the benefits, and some show the benefits outweighing the drawbacks.
I don’t know why you keep bringing up the argument that there’s only one good outcome and several bad outcomes. First, it seems to depend on how finely you want to divide “outcomes.” But even if there is only one good outcome and several bad outcomes, it is a logical fallacy to deduce that the bad outcomes must therefore be more likely.
I agree that not everyone is psychologically fit to own a gun. If you are prone to fits of violent rage, then you should probably not own one. But again, this is not generally something random or sudden for an individual. A person doesn’t suddenly become violent once he buys a gun; an adult should be capable of making that judgment about himself. (And of course people who have demonstrated their unfitness by prior violent acts–these being the best predictor currently known for the likelihood of further violent acts–are generally disallowed from owning guns.)
Well, once you point out all of the people who call guns a panacea, I will agree that they are wrong; but this is really a strawman argument. A gun is a tool for self-defense. It is far from the only one, and in fact not the most important one. The gun is no use until the attack has begun; some attacks (robberies, rapes, etc.) may take a long time to complete, during which time the gun can be very useful as a tool for defense, not retribution.
But again, your counterarguments are hypotheticals, and the evidence I have seen does not seem to show them to be common–at least not common enough to vastly outweigh the good outcomes–in reality. Note that these arguments ought to apply equally well to police; and police still go armed. Police, of course, are trained in handgun use, but this sort of training is not something magically restricted to police; as I (and several others) have said, getting training is definitely recommended if you want a gun for self-defense.
There are a few types of gun accidents that I would not classify as negligence, mostly materials failures and mechanical malfunctions. These are quite rare (and mostly due to negligence even then) but manufacturing defects do sometimes happen.
I don’t think I’m demonstrating particularly great faith in humanity here. What I am saying is that most of the risks you quote can be vastly reduced with training. (The fact that gun accidents continue to happen is plenty of statistical evidence that not everyone is intelligent enough to learn how to use their guns.) I do think gun training should be much more widely available and promoted. But as with most tools, people end up making individual choices about how proficient to become in their use, and some of them end up lopping off fingers in band saws.
I don’t know what you mean by “preemptively” here. Are you imagining people going out and shooting “potential killers”? That seems somewhat unlikely. On the other hand, pulling a gun on a rapist might be considered “preemption” but I would certainly consider it proper.
[I agree with you that the initial analogy was flawed as regards prophylactic measures; I was proposing an analogy that I felt better fit. But really I don’t see much point to arguing over analogies; one subject of debate is plenty.]