Robert, if I may, my view of what Harris is about differs from yours in a number of ways. I've read about 75 pp. of the book, so I probably have some of this later material in mind as I give my reactions to your post on the Introduction.
I think this might give the impression that Harris' project is weirder than it actually is. Harris defines "science" very broadly, whereas most people, when they hear the word, picture professionals called scientists doing research of various kinds. While this kind of science comes into play as a tool to guide our goal-setting in the arena of morality, Harris in fact believes that we already have a scientific basis for much of what we believe to be moral. Saying that acting with kindness towards others supports the well-being of conscious creatures is a scientific statement that has already been tested. It doesn't even need to be tracked to the ultimate source of truth in physical changes in the brain that can be observed under the condition of the world that we would label "being treated with kindness." But of course, as the science of the mind progresses, we will be able to define better what positive emotion looks like in the brain and how positive emotions differ from one another. This research will be confirming much of what people just know and always have.
He places "well-being" at the end of that sentence, not "facts." Here I think you are beginning to use "facts" in a way he doesn't intend. The facts that exist--without any doubt, he says--are facts about states of the conscious brain. These facts relate to what we experience physically as joy, fear, love, hate, anger, etc. We then sort these out according to whether or not in the situation of the individual they are supporting well-being.
The facts that values translate into are facts about our emotional responses, as Harris goes on to say after the words you quote. If we only would respect these facts about the well-being of conscious creatures, then a large part of our moral confusion would be lifted, as the example of corporal punishment shows. But as you mention, educated people want to say that factual answers to moral questions don't exist, so they have no way of proving that corporal punishment is not just something they don't believe in, but wrong as well. Harris elsewhere points out the inconsistency in the common attitude that moral reasoning must be categorical and airtight for all situations, or else it is invalid; whereas when science is incomplete and not in a state of consensus, the situation is normal and simply an indication that more research is needed. However, even with more research, perfect consensus never arrives, and that is okay, more than good enough.
The separation of science from morality, what Harris rightly describes as the Hume-Popper firewall, is shown as incoherent by the example of health – just as we know some food is poison and some is good, we know some conduct is moral and some is not. How does this analogy hold up? So far so good, but Harris starts to get shaky when he asks neuroscience, his own specialty, to do more of the intellectual heavy lifting than it really can, by locating morality within a precise science of mind. What does the fact that neglect affects brain development really say about morality? Harris says (p10) that meaning and measurement must be reconciled, but then draws the unjustified conclusion, in a tactical stiletto argument aimed at the heart of his real opponent, that “science and religion … will never come to terms”. The invalid logic here involves the claims that because science values consistency, evidence and simplicity in its assessment of factual truth, “a clear boundary between facts and values simply does not exist” (p11), and that “religion and science are in a zero-sum conflict with respect to facts” (p24).
Some facts about food, facts that are based in human physiology, transcend the vagaries of culture, so we can say some true things about good and bad food. So too, some facts about well-being transcend mere cultural preferences; they're true regardless of what culture we're talking about, so we can say that some cultural practices are good/right or bad/wrong. If cultures automatically adapted themselves to whatever promotes maximum well-being, we'd have great moral health, but none of them do.
Morality for Harris isn't in any sense "within" a science of the mind. Science doesn't create morality, any more than religion does. Science will in various ways be helpful in guiding us to set moral goals. Harris uses as an example whether we should spend our next billion dollars to eliminate racism or malaria.
For me, it's clear what the effect of neglect on development says about morality. Since well-being is by virtue of our physical constitution the only thing we can really value, then allowing babies to have improperly developed brains is immoral and points to a need for action.
I'm not clear about what you object to in SH's statement about science and religion never coming to terms. He's simply talking about accepting as moral/immoral whatever revelation has specified, vs. designating as moral whatever is most likely to secure human well-being. That religions often don't care about the effects on well-being (at least in this world) doesn't need to be discussed in detail. Sure, we know that SH hates religion, but he has a specific reason here for wanting it out of the business of morality. He's also not any kinder to other sources of craziness such as the North Korean regime. I see no problem with the validity of his logic, and I wonder if you are taking his assault on religion as too broad-based.
It helps to have his explanation for the statement from p. 14: "To really
believe either proposition is also to believe that you have accepted it for legitimate reasons. It is, therefore, to believe that you are in compliance with certain norms--that you are sane, rational, not lying to yourself, not confused, not overly biased, etc. When we believe that something is factually true or morally good, we also believe that another person, similarly placed, should share our belief. This seems unlikely to change. In Chapter 3, we will see that both the logical and neurological properties of belief further suggest that the divide between facts and values is illusory." As for the need for condemnation of cruelty to be absolute and universal, this might be traditional in philosophy, but Harris has always said we won't have this in ethics, do not need it, and that it is not implied when we say that cruelty is wrong. Again, science doesn't give us universal agreement and consistency, either. I don't know why "cruelty is bad" needs to be seen as any less factual than "water is 2 hydrogens and one oxygen." Certainly from a practical standpoint, every human being is in a position to verify the facts of the first statement, while few can personally verify the second.
Of course, Harris would be well aware of the categorical imperative, but what use would he want to make of it if it obliges him to separate facts and values, precisely the fault his book argues against? I think that for him the "transcendental imagination" is roughly equivalent to our innate moral intuitions, which he doesn't slight in any way and doesn't say that science must somehow show us how to overturn. You charge that hostility to religion biases him to "transcendence in logic," but I'd ask you to define this and then to show how its absence nullifies his argument. The is/ought argument is one that he handles as well, capably I think, but that will be for another time.
Looking forward to that.