2 may be the more fundamental question, but I think I can answer it with a confident yes. Spinoza’s ethics, for example, is exactly this: an account of human beings’ emotional states and which ones are better and worse. The writing of an ethical text, on this account, is one more piece in the causal chain: it is motivated by good mental states, and in turn motivates good mental states in others. But all of this remains, in some sense, inevitable. More recently, Alasdair MacIntyre in Dependent Rational Animals developed an ethical theory about dolphins: what it is for dolphins to flourish and what it is for them to live poorly, deriving from their natures. One could, I think, do the same about butterflies, at least in principle – not that the butterflies could read it or understand it, of course, but one could say what would count as a good life for them.

I haven’t read Poussin’s book, but I’m a little skeptical. I tend to think that Buddhists (at least classical Indian Buddhists) generally lean toward hard determinism, and I’m not sure if the concept of cetana really changes matters. I could be convinced on early Pali Buddhism, but I really doubt that Poussin is right in Santideva’s case – S rarely (if ever) uses the term cetana at all.

Both kinds of morality are significantly narrower than ethics, but the distinction between them is very important. We might need three terms here, really. I think Buddhists do have morality in the second, Williams sense, as in the sutta texts you point to; it’s a very minor part of the tradition’s concern, which I think is one of the reasons people like Damien get frustrated in looking for “Buddhist ethics,” but it’s there. (Santideva also points to such duties, though very briefly.) On the second kind of morality: I actually wonder whether a lot karma and its effects (such as the hells) should be thought of in terms of blame and punishment. They’re laws of nature. If I get lung cancer from smoking, am I being punished? Only in a rather metaphorical sense, and I think the same applies to the fruits of karma.

Would you say that early Buddhism, the Tripitaka, has a mix of moral and ethical teachings? Those that focus on kamma, anatta, nibbana are ethical while those talking of family duties (the Sigalovada Sutta comes to mind) or relationship with the laity (namely in the vinaya) constitutes moral teachings?

But doesn’t Shantideva mention Avici hells, further suffering, and such as punishments (as warnings?) for failure to be ethical (moral?)? Are *we* to blame for our own bad actions?

My own answer would be that concepts of blame and praise are irrelevant to Buddhist Ethics, much as metaphysical speculation – poisoned arrow, yada yada – unless it’s clear that what we’re doing IS actually helping to reduce suffering. But then all of Buddhism would be arguing against blame and thus be ethical and not moral.

There are a lot of issues to figure out regarding free will, for sure. What you describe sounds less like a true free-willist position (ie a so-called “libertarian” position like Augustine’s) and more like a compatibilist position (à la Siderits) in which determinism is held to be compatible with the traditional moral concepts (blame, obligation, punishment). I think Śāntideva’s argument is trying to push us away even from compatibilism, though: he is trying hard to argue against blame and punishment. In other words, no, other people really aren’t to blame for their bad actions, and we should stop responding as if they are. It is still good to become better ourselves, and to make other people better, and Śāntideva specifically writes with the hope of making himself and others better. But there’s no free will operating here. One could say there are choices, but it depends on the meaning of choice: one’s choice is determined by one’s personality, which in turn is determined by other causal factors. (He’s primarily thinking of karma, though I can’t imagine him objecting to seeing genetics and environment playing a role; they may be the mechanism through which karma works.)

I am still not completely decided on the issue, but I prefer the practice of equating “ethics” and “morals” as two words meaning the same thing from two different languages. It seems more precise to speak of unreflective morals or ethics vs reflective ones, reasoned ones vs unreasoned, and so on. Exploring what that reasoning is, we can then ask if the moral statement or action is, to use Kohlberg’s terms, pre-conventional, conventional, or post-conventional.

Regarding free will, it is a bit like consciousness in that it is a common-sense view and needs to be cogently argued against in order to reach a determinist position. I’m not sure that breaking down the causes of our actions, as Shantideva does, represents an argument against free will. Most free will advocates will concede that all of our actions are conditioned by countless forces, but that we still in the end have choices to make. A free will advocate can well argue that we must deeply understand the conditions for our choices, and then strongly urge us to forsake the unethical choices we could (and typically do) make in favor of ethical choices: ones that recognize interconnectedness, compassion, and so on. As a novice Shantideva reader, this is what I take him to be doing here.

Best wishes and safe travels!