Bones-O!, you didn't actually argue why harming people is wrong. Ok most of us belief it is wrong, but is it really wrong? What is the measure of wrongness for it?
You cannot deduce from harming people that harming people is wrong outside of acknowledging that one a) would not want to be harmed, and b) ascribes 'wrongness' to our harmers. There is a benefit in all of us avoiding particular actions that have immediate benefits to us, or simply produce pleasure in us. That benefit lies in an implicit contract between social
animals. If I don't harm you, you won't harm me. This is all 'wrong' is - a breach of this contract.
But you did miss the point of my question. You want to know if masturbation is wrong. Look to other things you know
to be wrong, even if you don't know why
they are wrong, and make an assessment of whether masturbation has in common with these other wrong acts that which makes them wrong.
For instance, harming others is deemed wrong (whether we know why or not). Does masturbation harm others? No. So at least with respect to the morality of harming others, masturbation is not immoral. But are there are things that don't harm others that are wrong?
And I would also argue that all behaviour, including personal pleasure not harming others, needs to be evaluated morally. If I can do A or B, then either A or B will be the better choice. If neither are especially bad, but one produces more happiness then do that. If both produce equal happiness but one uses more costly means then do that. I believe that either A or B will be the more moral.
I wouldn't necessarly argue this is wrong. It is an extension of the moral obligation to others to ourselves. The idea of having a moral obligation to ourselves is rather counter-intuitive, though. The necessity of moral obligation is that we will not, for instance, harm someone to increase our happiness.
I do tend to integrate the three big theories (Natural law, Kant and Utilitarianism) but only because they SEEM reasonable, whether that is actually correct morality i don't know.
Well how about chucking existentialism in there? The 'correct' morality is the one you arrived at in good faith, with authenticity.