You raise some good points; however, my comments were meant to draw attention to other methods by which we can get people to arrive at a more scientifically-minded ethics without training everyone to the same level of scientific competence.
Without getting too far into the weeds, I think we have one major problem: the human condition is naturally geared toward the narratives of human corruption (death), sin, and redemption. Let us put aside for the moment that all these things are either something we cannot cope with psychologically or that they might represent illusions stemming from our social milieu. The question is, how does one convince a fellow human being that death is just natural—not a curse, and that sin and redemption probably stem from our fears of ostracism and not alienation from God?
I think this is a very complicated question. We cannot expect to just lay our case out logically and have people fold under the pressure of a superior argument. From their perspective, what is superior about an argument that makes life existentially meaningless and infinitely absurd? How does science address the gnawing and nauseating experience of alienation and isolation?
Yes, science will eventually determine the parameters within which the “normal” brain functions when it comes to input, processing, and output. However, even a properly functioning brain cannot ignore that humans exhibit highly irrational and contradictory desires. For example, how do we explain morality as a function of human well-being when some choose to brave life and limb to satisfy ego and obtain social “wealth”? Is it moral to restrain those who take chances that undermine their own physical well-being? How much should individuals be restrained if their activity threatens the well-being of others? How do we measure that well-being, only materially or also psychically?
The complexity of these questions have been addressed by many. Plato and Aristotle are good places to start the discussion but we must move on to more modern sources of inspiration. I have found the work of Michael Sandel very helpful in this regard. What Sandel does best is expose the simplistic weakness of ethical systems like utilitarianism and libertarianism, arguing Harrison’s point in a different way. Sandel says that all ethical systems have to have a “telos,” but that telos is not always easy to find. Sandel suggests, and I am inclined to agree, that any telos has to be blind to outcomes ahead of time. In other words, a morality that naturally advantages one group over another is not a truly just moral system. Rules are rules, to use a cliche.
Again, we are are getting too far into the weeds, and away from your point, which is that science can serve as an epistemological basis for navigating the moral landscape, or what is good and bad for people. However, I think we are mistaken if we think morality can be reduced to a formula, because the well-being of one too often comes at the expense of another, especially in a world run by politicians, businessmen, and accountants. In this respect science gives us one of the fundamental principles that we need to understand in order to create a better ethical system: the law of conservation. Understanding that nothing comes free helps us to understand that any ethical system will be limited by the same law. There is always, at any one time, only so much to go around, so until we have fusion generators, replicators, and a cure for every disease, including aging, our ethics have to address scarcity in all its guises.
There is still much to say here about science as methodology and as a body of knowledge itself. Both present challenges because getting people to think like a scientist is unnatural and because science as a body of knowledge has only one “evangelical” outreach, and that is technology. Unfortunately, most people can use and enjoy technology without any appreciation for the science behind it, and in some cases they can use that technology with outright animus toward the science on which it was built.
My point is that science has an integral role to play in the science-based liberal capitalist system that seems to be taking over the planet, but that role must be supplemented by other efforts at communicating that worldview. I notice this is happening in the skeptical community, which is encouraging people to collaborate with film-makers, storytellers, and actors to get “the message” of science out there. I think literature, history, and other humanistic endeavors can also abet this evangelical effort.
In short, we should leave no stone unturned in our effort to bring people to a more scientific, more just, and more moral world.