Standing around thinking to myself about some idea on martial arts, I've came up with the hypothesis that the goal of training is to be able to consistently mitigate and/or reproduce the effects of luck in a confrontation. Those two terms seem contradictory, but let me explain, since it's really a matter of perspective.
Put two untrained individuals in a fight and let them slug it out. Most likely, you will see wild swings, some weak kicks, probably some biting, and most likely it will end with one person too tired/hurt to continue, or a luck hit that ends the fight. Targeting will probably be terrible: punches that hit the chest, hooking punches that go to far and make the forearm hit, etc. In this case, the luck is your opponent not being able to continue or you landing the strike that ends the fight.
Let's focus on the strike. Wild swings can be very ineffective. Punch someone in the pectoral and you're not going to get much of a reaction out of them, unless you know koshijutsu and understand where to hit (this is one of my favorite ways of screwing with my friends). Similar for strikes to the skull, especially if you hit with the wrong part of your hand. However, a properly aligned strike to a proper part of the jaw can cause a knockout, and one to the nose can incapicitate.
So you take the wild swinger and train them in some form of punching, like boxing. By teaching them how to strike and where to hit, you increase their chances of reproducing that hit that will damage their opponent. They train to the point where they can reproduce the technique on command. Now, as MMA has shown us, there's no guarantee to the hit knocking the person out every time. However, if when the person started, it was a 1 in 50 chance, training has reduced that to maybe a 1 in 5 chance. So, that's the reproduction of luck.
From a defender standpoint, you are attempting to mitigate their luck. If someone is punching you, you are attempting to lower their chance of hurting you.
However, this is really just a reproduction of luck all over again. Assume the attacker has some level of skill, and throws a punch. If our untrained defender happens to get out of the way, that was luck. If the attacker knows what they are doing, the defender will eventually be beaten up, yet somewhere in there, the defender will be lucky enough to avoid some punches, and maybe get a lucky, fight-ending punch in there.
Training is to reproduce this. Instead of getting hit 50 times in a fight, training to reproduce a valid defense may reduce this to 5, with the hopes of it being zero (although that may just be another level of luck). In fact, good training should give the defender the ability to have some control over the fight such that they do not find themselves in range of so many punches to begin with.
