My line of thinking when it comes to the deterrant factor of open carry is that it's kind of along the lines of locking my car doors, it keeps an "honest person honest."
To take this one step further, the deterrant argument applies a rational thought process to a group (criminals) that has been known, at times, for irrational thinking, for whatever reason. Drunk, high on drugs or desperate to get drugs, or just one of those who isn't right in the head to begin with.
The main reason I prefer to carry concealed is based on the advice of a close friend who had vast experience with weapons in his chosen profession. In fact, prior to his death, he had been in 28 countries of the world and had killed someone in darned near every one of them.
He told me that any opponent I may have to face shouldn't know my capabilities until they were on the receiving end of those capabilities. If they know what you are capable of they can take steps to defend against those capabilities.
This jibes with what another close friend told me. This friend has attained the highest level of Escrema, which I think is also called Corto Seguida (sic) and is Phillipine stick & knife fighting. He is also a Master of the Blade in Japanese sword fighting. I used to be his training dummy for years and many times he used to say, "If you ever have to use a knife for self-defense the first time your opponent should know that's what you're doing is after they've been stuck with it, preferably more than once." It goes back to the defending against your known capabilities.....
Does open carry deter some criminals?
I have absolutely no doubts that it does but I'm not going to stake my life on it deterring all of them.......
One last thing and this deals with odds. I have heard the open carry crowd, whom I support by the way, say that the odds of you being singled out because you are open carrying are slim to none.
For years I took canoe trips in northern Canada and when friends would ask if there were any bears up there I would say yes, there's some. They would usually follow up by asking if I carried a gun for protection against them (bears) and would invariably think I was taking a big risk when I informed them that it was against the law to carry a weapon up there unless it was hunting season. My pat answer was, "The odd's are one in a million that I would be attacked by a bear."
During that time in my life I was invited to a friend's family reunion and felt honored when I was seated next to his grandfather, the Grand Patriarch of that reunion. Little did I know that I was being set-up.
During the course of conversation the grandfather asked me about "my trips" and it ended up with me going / being led to my "One in a million" speil. A little later the grandfather said, "Come with me son." He then took me out behind a garage where the rest couldn't see us and handed me his beer saying "Hold this." After he handed me his beer he started to take off his shirt, which I thought odd, then his t-shirt, which really had me wondering, this was until I seen his upper body, which was covered with some nasty scars.
Even though I had a good idea I asked, What caused those? He answered, "A Black Bear." I won't go into his attack but will say that he had been cutting wood in Northern Michigan for a couple of hours before he was bum rushed by the bear so it wasn't as if he suprised it and it instinctively attacked.
He then said something that I'll never forget.
He said, "Son, you mentioned that the odds of you being attacked by a bear were one in a million.....while that may be true I can assure you of one thing, the last thing you'll be thinking about when you smell the foul breath of a bear in your face are odds."
Every time I hear the odds argument I think of that older gentleman and the lesson he taught me that day.......
I still continued to take trips, it's just that I took more precautions after meeting "the grandfather" in order to tilt the odds a little more in my favor.......
If someone feels that open carry is a deterrant then all the more power to them. It's a personal choice that we make based on our own experiences, which are unique to each & every one of us and by me relateing some of mine I'm not saying that I'm right and others are wrong, it's just where I'm coming from. Different strokes for different folks.