Originally Posted by
Xei
Nobody knows. It just always has done. Maybe it won't one day. There's no telling if it's a necessary or otherwise. This is nicely demonstrated by the issue of the half-life of a proton. Nobody has ever seen one decay. That doesn't mean they necessarily don't decay. It just means we've never happened to see one decay. Maybe they do have a half-life, of a googol years. Maybe the half-life is a second.
I'm glad you answered this clearly because this was the whole reason I asked the question.
The laws of physics are not a priori categoricals, or 'logical', as you put it. They are simply an expression of an observed pattern, a posteriori.
Let's focus on the law at hand (well, there are a few laws we could invoke for the same effect, such as conservation of momentum, which is in itself telling, but let's stick to your advocated 'law', although it's more an instance of a general theory than a law of physics per se); the atoms of the golf club exert a force upon the atoms of the golf ball. To be more precise, the electrons of the club atoms are negatively charged, and exert a repulsive electrostatic force upon the electrons of the ball. By definition force is the acceleration per unit mass, so the ball accelerates forwards.
Now the next question: why does an electric charge exert a repulsive force upon a like electric charge? What is the causal link between the presence of a point with an abstract quantity we refer to as 'charge', and the acceleration of a second point to which we also attribute charge? How does one cause the other? And if an electron failed to accelerate another electron, but perhaps decelerated it, or did not move it at all, what would be our logical objection?