Ken wrote that my previous posting misinterpreted his theory concerning the science of morality in some way and a correct interpretation will show that it avoids the objections I raised.
I look forward to his response.
In the mean time, I would like to address the standard response that I typically get at this point in the argument. The fact that it is the standard response suggests that a few readers will have this response in mind even if Ken does not prove it.
In this response, the person I have criticized, or some advocate in defense of such a person, will typically tell me that I wrongly assumed their theory provides moral prescriptions.
The theory, they tell me, was not meant to tell us what is right and what is wrong as a matter of fact. It was only meant to show us that there is a material explanation for what is going on in the brain when people make and defend moral judgments, and when they behave in ways considered moral. This, they tell me, is both interesting and important science, and they support it.
I don't deny that this is interesting and important science. I also do not argue that it is wrong to support it.
But the people engaged in this science are not, in any way, studying morality. They are studying attitudes and beliefs. They are not studying morality itself.
We can conduct all sorts of studies of what goes on in the brain when one thinks about the stars and the planets. We may well provide a long list of material explanations for that set of phenomena. However, the person who conducts these studies is not an astronomer. And the person who supports these studies is not supporting the science of astronomy.
The astronomer studies the stars and planets themselves, not thoughts about stars and planets.
Similarly, the ethicist studies what is right and wrong in fact, not thoughts about right and wrong.
When a brain scientist studies thoughts about stars and planets, he cannot even get to the conclusion that the stars and planets are real, let alone to any conclusion of what properties they have in fact. We can have a similar study about thoughts of unicorns, or thoughts of God and the claims made in scripture. These may well be interesting and important scientific investigations. However, no matter how well developed these studies get, you can't get from the fact that these thoughts exist in the brain and can be studied, to the conclusion that unicorns and gods exist as a matter of scientific fact.
Some "moral scientists" admit this. They go ahead and say that the study of moral attitudes is the study of a biologically compulsive fiction. There is no "right" and "wrong" in fact, they tell us. However, biology and evolution has compelled us to act as if these things exist because this compulsive fiction is biologically useful.
But what if scientists had come to the conclusion that the planets and stars were also biologically compulsive beliefs - that there are no stars and planets (the earth is the only thing that exists), but we are compelled to believe that there are stars and planets because these beliefs were useful.
What implications would this have for the study of astronomy?
It would not, in any way, justify that particular science. It would, instead, show that the science of astronomy is illegitimate. It may be a biologically compulsive illegitimacy, but illegitimate nonetheless.
The same may be true of morality.
In order to have a true and legitimate moral science, it has to be possible to write a scientifically sound scientific paper capable of passing peer review that provides proof of a proposition of the form, "Capital punishment in the case of rape is morally impermissible", or "the right to the freedom of speech does not apply to advocating sex between adults and children or depicting them in a positive light," or "each person has a moral obligation to give 20 percent if their income above $20,000 per year to charity."
You don't have to defend these specific claims, but you have to be able to demonstrate that claims like these are defensible.
The current "science of morality" utterly fails to do this because it contains the leap from, "People have an attitude that P; therefore, P". This can never be a part of a sound scientific argument. This can never generate the types of proofs that are necessary for a moral science. Certainly, the attitude that P is a real event subject to scientific investigation, but you have to get P itself to have a moral science. The attitude that God exists is a real event subject to scientific investigation. But it will not prove the legitimacy of religious beliefs until you can get to the conclusion God exists.
So, if somebody wants to respond that I misrepresented their theory - that it was not meant to offer scientific proofs of moral propositions - then I argue that they do not have a science of morality. Their study is as far removed from ethics as the study of thoughts of stars and planets is from astronomy.