In trying to refute The Moral Landscape: How Science Can Determine Human Values, in the way that the linked blog does, I believe that it’s quite unimportant whether or not
What the linked Darwinian response criticises Harris for, among other things, is that he doesn’t formulate a rightness criterion, despite that he claims that science implies some kind of impartial hedonism. But if there really is an implication it should be possible to formulate what is implied! Of course Harris should tell us more exactly which values he says science can determine. It’s hard not to suspect that Harris, in order to evade legitimate criticism questioning the existence of any implication, wants to avoid being more precise. The linked Darwinian response also claims that the strongest version of impartial hedonism is classical hedonistic utilitarianism (although not at all supporting that moral theory). The intrinsic value of hedonistic utilitarianism can be formulated in terms of pleasure over suffering, or in terms of well-being.
Richard Dawkins has actually been criticised for claiming that genes emotionally are selfish! Can genes be any more selfish than atoms can be jealous or biscuits can be generous? Yes, actually, to their effect. ‘The ethic of animals’, as described in the Darwinian response, is, as I read it, clearly not a moral theory which all animals consciously and reflectively understand and share through language, but rather the moral theory which animals closer than any other moral theory over time unconsciously tend to practice. They do that due to the ultimate biological cause of their behaviour, namely natural selection. Personally, I don’t find it any more nonsensical than the selfishness of genes, that the formulation of the ethic of animals is deduced from, not what animals reflectively think, since they hardly do, but, what they actually tend to do.
Reading the Darwinian response it’s also clear to me that it doesn’t violate Hume’s law. It nowhere claims that it’s right in any higher meaning to behave according to ethical fitnessism solely because animals behave according to it, which they, by the way, don’t really do, even though natural selection tends to make them come quite close.
I disagree that any of those three points are unimportant, they're central parts of Harris' argument and they are part of what has to be refuted.
The idea that there has to be a "rightness criterion" (or an "intrinsic" criterion as per the article) is very much what Harris' view questions, and his position has very little to do with hedonism (hedonism is just a partially-intersecting sub-set of what he's talking about).
To violate Hume's distinction, you don't need to say there's a "higher meaning" in fitnessism, you just need ...
I noticed that there has been some earlier discussion about Sam Harris’s Moral Landscape Challenge here at LW. As a writer on the Swedish politico-philosophical blog The Inverted Fable of Reality, I would like to share a response to the challenge, written by our main contributor, which I believe is interesting to read even if you are not familiar with The Moral Landscape or its content. See this link for the response and a short explanation of the challenge.
The response takes a different approach to most responses to the challenge. It is divided into four parts and starts by asking which ethic is most compatible with science and reality and finally tries to answer this question.