That argument has come up before and it is flawed in many ways. First, the assumption is that the men and women in the military would all choose to follow the dictator that is telling them to subdue their own people. I would hope, and expect based on the members of military I know, that this would not happen. If we don't believe this, then it's over for us and we might as well give up. The Constitution is dead and we have no more power.I found this really insightful post on: http://www.allegianc...i-want-fly-f-14
This line of thinking - particularly with regard to present reality behind the notion of defense against tyranny - has occurred to me over the course of this debate. This guy put it in words pretty well if you ignore some of the "less eloquent" bits around the ends of his argument.
Second, I've had people say that it would be pointless to go against our military since they are so powerful and would squash us. I say to them, ask the dictators in the Middle East, or even our own military members that were in Vietnam, Iraq, or Afghanistan, how an armed population with mediocre weapons and ingenuity can cause trouble for a military power.
Third, I've actually had people say that we should abolish the 2nd Amendment because it is no longer necessary. Assuming that this is true, it ignores the fact that we have reached a point where we believe it is not necessary BECAUSE of it. If we did not have the rights provided us in the Constitution, and a people that have taken it to heart to protect it and not let it get ripped up, we probably would have been disarmed a long time ago and would already have a dictatorial government by now. My guess is that the Civil War is where our freedom experiment would have ended.
So, regardless of how relevant we think it is, the Constitution and core "safety against the Government" Amendments must remain in place to protect from the unknown future more than to protect from what we perceive as the current relevance.