From a debating point of view, selfish and selfless are only really useful when you mean them in their literal meaning. Someone is being selfless when they deliberately stay in a job that they hate without any justification. That person succumbs to depression and anxiety. The other people that work with them fear and dread being near them, because they’re going to get their heads bitten off or have to listen to the same massive rants over and over again.

They’re being selfless, but all they’re doing is hurting everyone else and importantly they’re hurting themselves too. The selfish thing for that person to do would be to leave the job and go find another one, one they actually like.

The important bit is working out who and how someone is benefiting in deciding whether something is a ‘net good’ or a ‘net bad’ such as these things can be objectively evaluated. Whether or not someone is being selfish or selfless when they act is completely irrelevant.

If something is hurting someone then just say so, and leave the “words that mean too much to be useful to anyone” (like ‘liberal’) well alone?

I think your understanding of the natural usage of selfish is different to mine (and as for the idea of a “natural” use of language…). As far as I can tell, people use the word “selfish” when they want to use pejorative language to describe someone else’s actions or thoughts. My understanding, instead, suggests that there is nothing wrong with acting for oneself and, I agree, that is how everyone acts.

Much better to accept that and move on. People are selfish bastards and yet somehow that lets us all to rub along. The best part about Libertarianism is that how someone thinks (let alone feels) is irrelevant to the rest of us, provided how they act does not infringe on other people’s liberty.

Yes, when you use the word selfish in a way that robs it of all meaning.

Clearly all my acts result directly from my desires, values and intentions, and not somebody else’s. In this sense all acts are selfish, and so describing an act as selfish in this sense tells us nothing about it.

So it remains useful to use words like selfish and unselfish naturally to distinguish between different kinds of motivations, according to how an individual feels about helping or hurting other people.

I obviously didn’t think about this one enough before posting.

Next up: Socialist Batman!

In essence, all charitable giving is fundamentally selfish, it’s just people are unwilling to accept this.

Of course in the case of Superman, being an alien might mean he does obtain meaningful rewards from being selfless – you assume that aside from superpowers he otherwise functions in the same way as human beings, which seems improbable.

It won’t be.
Not only is Atlas Shrugged 1100+ pages of badly edited self-indulgence and leaden dialogue, but John Galt has no known superpowers either.