Having watched it, and read its follow-up, I have to say I’m a bit puzzled. I don’t see anything controversial or novel here. And I think the title is wrong.
(I)t is taboo for a scientist to think such things, much less say them public.
I have good news for you, Sam: nobody thinks of you as a scientist.
Everyone thinks of you as a writer. I know you do neuroscience, which is ostensibly my field, but I don’t know what kind of research you do. I had to look, and I had to look pretty hard. You have a grand total of two peer-reviewed publications containing original data listed on your website (here’s one, and here’s the other). Sorry, but your list indicates that even you don’t think of yourself as a practicing scientist.
On to his points, and why I see them as trivial.
First, Harris attacks ethical relativism, and makes a big deal of his proposition that there are definite answers to moral questions. I have never met a philosopher or ethicist that seriously proposes or defends any form of ethical relativism. Harris claims to have met them, and I am sure that they exist. But the point is, this is not contentious or particularly insightful on Harris’s part.
Second, Harris says that point of ethics is to promote human flourishing. This sounds one heck of a lot like utilitarianism. Utilitarianism is a well-described and argued moral theory. Again, nothing controversial or new.
Third, I don’t see how Harris thinks science can answer moral questions, in this sense. Practicing scientists are always harping on about how science is a process. But Harris is, as far as I can see, mum on what processes we could use to answer moral questions.
Should we do double blind, ramdomized control experiments? Do we demand one group take a particular course of action, demand the other group not take this action, and measure them again at some point to see which group has undergone more flourishing? Because that’s empiricism, and that’s the way we do science. Maybe this is a good way to go (though I have doubts). But Harris doesn’t say.
If you want to say “science can do this,” you have to outline a research program. Harris doesn’t.