Okay, going back to the proposed situation of a mugger with a gun or a mugger with a knife.
First off, disarming someone with a knife. Even with the most basic training, or even none, you can disarm someone with a knife. An overhead strike - very easy to block, you merely stop their arm and then they are open to counter - attack. Straight thrust - again, very easy to block or evade. The most dangerous are little flicks/slashes with a knife, not large movements because they are harder to block. However, if they are close enough to begin slashing etc. then I'd say you have more than a fair chance of taking them out. Unless you're an invalid. In all of these scenarios of attacks, you really should come out of it with minor cuts to your arms at the most. Your belly is your most vulnerable area when fighting someone with a knife - However, as I just said, thrusts to it are easily blocked. quick little slashes are the most dangerous, because if they can get close enough, and move fast enough to evade your block, and actually hit you, and put enough power in.... then yes, you are in trouble.
One other thing - which is it easier to run away from? A gun, or a knife? Last I heard, knife's weren't really a ranged/projectile weapon so unless the mugger is close, you can probably get away. (Please note, I'm talking about a situation with one mugger at the moment) A mugger with a gun - well, who knows, you may look pretty with a bullet in you. If you get them to place it right, in some kind of pattern, you could make a fashion statement. "Blood - red - blotched -pattern - shirt, $150".
Now, on the other hand, a gun. Could I just point out one thing - You are not Neo. You cannot dodge bullets. I've never shot a gun, but I had a chat to someone who has - it would be fairly hard to miss someone at the range of say 1.5, 2 metres. And a bullet doesn't just make a clean hole, or cut like a knife. It smashes things. Permanent damage in some cases.
yeah, just like it was a danger in the McCarthy era. It truly was a big fear. The realities behind that fear are quite another problem. I don't know enough of British history to comment on how possible it was there, but a serious uprising that could do anything was unlikely at best in the U.S. Not that it stopped certain senators from raping the Constitution to find anyone they could label communist and ruin their lives.
The reason for British gun laws, originally, was to head off a possible Communist uprising. Apparently it was quite a big danger at the time.
Newsflash: Communist uprisings really aren't a threat anymore. Seriously. As Jam said, you'd rather carry a gun, the very
nature of which promotes violence, because you're afraid someone will attack you? Or that there will be a communist uprising? Or that your conspiracy theories come true and the government tries to become a dictatorship? Well, I'm sorry folks, that may be a real threat in the US of A, but it sure isn't here, so I'll take my chances.