Cheats prosper until there are enough who bear grudges against them to make sure they do not prosper.

So why don't we make ourselves the last generation on earth? If we would all agree to have ourselves sterilized then no sacrifices would be required - we could party our way into extinction!

Lay off with the 'You reason, so you don't feel' stuff, please. I feel, but I also think about what I feel. When people say we should only feel I am reminded of Göring, who said 'I think with my blood.' See where it led him.

If possessing a higher degree of intelligence does not entitle one human to use another for his or her own ends, how can it entitle humans to exploit non-humans?

It would be nonsense to say that it was not in the interests of a stone to be kicked along the road...A stone has no interests because it cannot suffer. The capacity for suffering and enjoyment is, however, not only necessary, but also sufficient for us to say that a being has interests - at an absolute minimum, an interest in not suffering. A mouse, for example, does have an interest in not being kicked along the road because it will suffer if it is.

Marx saw that capitalism is a wasteful, irrational system, a system which controls us when we should be controlling it. That insight is still valid; but we can now see that the construction of a free and equal society is a more difficult task than Marx realized.

At the descriptive level, certainly, you would expect different cultures to develop different sorts of ethics and obviously they have; that doesn't mean that you can't think of overarching ethical principles you would want people to follow in all kinds of places.