It's not a logical fallacy to discuss weapons that are more dangerous than ones we can currently have.
The question is: what makes machine guns much more dangerous that the average citizen can't be trusted with them?
There's two parts to that question. The "average citizen" in this argument is not a criminal and is not likely to ever shoot another person (except possibly in self-defense). Nothing that this person, the "average citizen", possesses is dangerous. If I had a nuclear weapon or nerve gas, no one would be in danger because I wouldn't use them.
But there's a second part to the question, which is what makes machine guns more dangerous than what is currently commonly available?
That's a stupid question. You know perfectly well that machine guns are more efficient killing machines. The reason that our military uses them (and that includes 3-round burst, since that's a "machine gun" under federal law, even if it's not fully automatic) is that multiple shots with a single trigger pull is more deadly.
Your response is going to be that "average citizens" like you and I, who have no intention of ever killing anyone, should be able to own such things. I agree.
However, the reason that many people think the current state of affairs is okay is that if they were available without a $200 stamp, high price tag and background check by the ATF, more criminals would have them and would probably shoot more innocent people with them.
Think about it--criminals use pot-metal guns from manufacturers like Hi-Point and Jennings. (You know, unless they can afford that "Glock Forty" because they sold enough drugs.) They buy what's cheap. If full auto were legal, some of them would be VERY cheap indeed. A Sten is easier to build full auto than semi-auto, and it's made of out a damn piece of pipe.
Now I'm not saying that I agree with these laws. But I'm saying that, in our democracy, there's a general consensus that "reasonable restrictions" can be imposed on the right to keep and bear arms. And I'm willing to bet that a majority of people think that it's reasonable to restrict fully automatic weapons. They think it's reasonable not because they worry about what honest, average citizens would do, but because they're worried about how much easier it would be for a criminal to obtain a fully automatic firearm, which are definitely more dangerous to innocent bystanders than semi-autos.
Right or wrong, arguing that they're less dangerous isn't the right way to win this argument.
And if you think there shouldn't be "reasonable restrictions" on our 2nd Amendment right, first realize that there are also "reasonable restrictions" on our right to religious freedom and our right to free speech. If you think we should be able to own fully automatic firearms with no restrictions, then ask yourself if people should be able to smoke marijuana as part of their religion or if they should be able to scream the proverbial "fire" in a crowded theater.
I honestly think it's a little conceited to basically make a thread where you're saying "All 'gun' people should agree with my view on guns, otherwise they're anti-gun." In a democracy, everyone is entitled to think their opinion is correct, but that doesn't make it true.
Aaron