what are we supposed to say again when christians ask us where we get our morality?

[Esquilax]

Since using your definition we are only concerned with the well-being of sentient beings who are capable of moral thought then is it not morally wrong to torture animals?

Whoa, whoa, when did I ever say that only sentient beings who engage in moral thought are a part of our moral metrics? My definition concerns the well-being of all living creatures, whether or not they engage in moral thought; even if an animal can't participate in moral conversations, causing it unnecessary pain would still be immoral by virtue of the pointlessness of doing it. Why negatively impact any being for no reason?

Why does complexity only matter at the sentient level? That seems rather arbitrary. Does this also apply to the intelligence of the individual?

Arbitrary? The more sentient an organism is, the more potential it has for complex thought, emotional nuance, and so on. You lose more potential good, potential anything, through the elimination of a person than you do a fish.

This has two problems with it. Firstly, pain often does serve a purpose it prevents us from harming ourselves significantly. We stop running on an injured leg because it hurts, we do not get to close to fire because it hurts and so on.

You're conflating the sensation itself with the cause of the sensation. When I say we dislike pain, it's precisely because the purpose of pain is to notify us of bodily damage and to warn us away from danger. There's no sense in which pain ever signifies that something good is happening to you.

Secondly, you’re assuming that we ought to treat others the way we want to be treated (sounds familiar).

Yes, it does sound familiar: Confucius was saying it years before Jesus did.

Why? I see no basis for this. If someone can inflict pain on others and better their own situation then why not? Who are you to tell them they have to worsen their own situation just so not to inflict pain on others?

Because we require each other to survive, and a world in which we allow indiscriminate injury for personal gain is demonstrably worse off for everyone involved; our society is what allows us to thrive and become the dominant species on the planet, and that is predicated on a certain level of trust between one another, that we can share resources and expertise with the expectation that we won't turn on one another violently at the first opportunity. We are disparate parts that come together to create a functioning whole, and without that trust our ability to do so breaks down.

Your local supermarket stays open because the people working there can rely on you to keep to the social contracts and pay them money for your food, rather than just murdering them for it. If they couldn't, there would be no reason for them not to act in their own self interest and not come to work. Consequently, there would also be no reason for the producers of that food to sell it to the supermarket, as they'd have no assurance that the buyers wouldn't simply murder them and take the food. It all breaks down.

Is this really such a complicated concept that you needed to be told it, Stat?

It’s unpleasant yes, not always bad.

True, when I get a flu shot the temporary pain is mitigated by the benefit I gain from the shot, which is why this is a general rule and not an all encompassing absolute. Context is an important consideration.

You’re still making a huge jump here. Sure, sentient beings are capable of creating moral systems and following such systems but I still see nothing that compels us to do so if we live in a purely material universe.

Again, we live better cooperatively than competitively.

Joseph Stalin died the most powerful man on Earth, why should a person not live their life like him?

Yes, and he became that on the back of the death and suffering of many other people, and most notably, his regime was in no way self-sustaining. If it had continued, things would only have gotten progressively worse; you can't build a society like that.

He’s feeding the worms now but if there is no god we all will be someday. Why should we care what worm food comes after us?

It's another facet of the social contract: we stand on the foundations given us by the previous generation, and we pass that along to ensure the survival of our species.

Incidentally, are you saying that you only do any good work now because you expect eternal reward later? And you question my moral foundation?

Why should we care about any worm food besides ourselves? In the words of Himmler, “What compels us to keep our promises?” More precisely, if a person can better their own well-being, then why not hurt others?

Answered above.

No games here; I think this is a legitimate question. If morality only pertains to sentient beings then it seems to follow that all acts against non-sentient beings are permissible and amoral. There are girls who are date raped and have no recollection of the event; is this act still immoral? I’d say yes, but given your definition it would appear not.

Unconscious is not non-sentient, Stat. It's a temporary cessation of certain brain functions, but it's not a lack of sentience.

Many people commit adultery and are never caught. If god exists this act is still morally wrong, given your definition of morality it would not appear to be. Your sort of pragmatic approach to morality falls apart when applied to very simple situations such as the ones above.

Adultery is the deliberate breaking of a social contract, albeit a less vital one. I've already explained why it's in our best interests to maintain our social contracts, even if we aren't caught breaking them.