Hi Lee. What if I have a baseball bat and the bad guy shows up at the door without a weapon or say with a knife. Assume that I would have no idea how to really hit him with it. Is that any kind of deterrent? Would he think, "ah crap, he is going to bash my head in" and decide to back off?
I know we don't talk about guns here but I am going to bend the rules and ask the same question here: what if I have an empty shotgun? Is it better than nothing? Again, assume that I have no idea how to use it and won't have any bullets anyway.
Some of the responses you've gotten can give the impression that once a person arms himself for self-defense, his respect for the sanctity of life is suddenly downgraded, and/or he would be a fool to not live up to some macho slogan.
In my experience, such has not been the case. I've been in several armed encounters with criminals, and in none of them was I the least bit inclined to "shoot first and ask questions later" or whatever. If anything, my alertness and moral clarity were hyper-sharpened.
In each case (there were four), my desired outcome was the best possible for both of us (no crimes get committed, and nobody gets hurt). My second choice outcome was not so good for him. I was the only one whose will, if imposed, would lead to the best possible outcome for both of us, and fortunately for him, I was able to impose my will and nobody got hurt. But Plan B was ready to go, and I think that willingness on my part was projected as confidence.
Let me tell one story of projected confidence. I was friends with a 75-year old attorney who was in the habit of carrying concealed. One day he was leaving a client's place of business rather late, and as he was walking across the mall parking lot, he got the feeling that something wasn't right. He turned and looked behind him, and several young men were silently running up on him (his hearing was poor, so his definition of "silent" was different from yours or mine). At this point they were about thirty feet away and closing fast. Several things happened all within about one second: His body crouched and leaned toward his assailants; his right hand decisively swept his jacket aside and back as it reached for his holster; he totally fixated on the young men like a predator on its prey (i.e. there was no time for fear, only purpose - and his purpose was "fight" rather than "flight"); and the young men executed a textbook Flintstones-style flailing-stop-and-run-the-other-way. But when his hand reached the holster, there was nothing there! Not even the holster - he'd forgotten to put it on!! The point being, he had projected such supreme confidence and focus that none of the young men doubted for a heartbeat that they'd just made the biggest mistake of their lives.
The only way to project such confidence is to have such confidence. He had it, even though it turned out to be false! He told me that if he had known he was unarmed, he would have been paralyzed with fear knowing that escape was impossible, and he would not have even thought to fake it. He would have had a very bad day, maybe his last, and several young men would have had a very serious crime on their side of the ledger, which would have made their lives worse too.
So at the risk of repeating myself, my two points are: First, if you choose to be armed, that is not going to change who you are. Your moral values and mental acuity will still be 100% intact. You will still have all the wisdom and kindness that you do now; added to that, you'll have power to impose your will when it's the only sane course of action, and therefore the best possible outcome for all involved. And you'll have a backup worst-case-scenario option that you wouldn't otherwise.
(Let me give a quick example: Has having power on this board transformed you into a jerk? Nope; if anything, it has probably made you less inclined to engage in verbal conflict, and when you've had to use your power, you have been especially careful to exercise good judgment and use it for only good. You would do the same with this other kind of power. In fact, I would speculate that you're exactly the kind of person who can best be trusted with this other kind of power.)
My second point is, confidence is a very powerful weapon, but it can't be faked. It's got to be real. Personally I'd grab an empty weapon if it was all that was available, and do my best to fake it (Plan B being "okay, now it's a club"), but that would not be my first choice. If that awful moment ever comes, I think you will want to have the options that the real thing + situational awareness + reasonable preparation can give you. I sure did.