I think that the fourth example is possibly more complicated than the others. The reason is that the “deriving pleasure” argument is only one of those put forward by those who are opposed to corporal punishment in schools. Others are:
it is an assault, and children too have human rights;
it isn’t, anyway, effective in modifying behaviour.
If possible, I’d like you to factor out these other arguments. Let us suppose we had some research which demonstrated conclusively that school corporal punishment was indeed effective; and suppose, too, we were comfortable that this particular type of assault could be regarded as legal. The question, then, is this:
Could the danger of over-zealous teachers — or, worse, teachers who use CP as an excuse to perpetrate indecent assaults — be coped with by a strictly enforced professional code? Or would this danger alone be sufficient to warrant a ban on school corporal punishment?