A wise man named David Hume once wrote that, in all the moral systems he had observed, at some point the author proceeds imperceptibly from “is” statements, statements about how things are, to “ought” statements, normative statements about how things ought to be. But they never seem to add the necessary logical step between—how one goes from those statements about the natural world as it is, to the statements about how it ought to be. In other words, morality. What has become known to some as Hume’s Law states that one cannot logically derive an “ought” statement from a series of “is” statements.
This is a philosophical question, and as philosophers are wont to do, they still argue about it, almost three hundred years later. Some claim that Hume’s Law is false. They subscribe to a theory called moral realism. Others claim that it holds, and they are called moral anti-realists. This whole philosophical field is called metaethics, and concerns questions such as what moral statements really mean, whether one can derive normative “oughts” from facts about the natural world, and related issues.
Science is in the business of describing the world as it is. As such, scientists are rarely interested in questions about how it ought to be. Or they might be interested, but they can only come with proposals, not actual, logically deduced demands about how people should treat one another. That is philosophy, not science. Science explores and teaches us about how the world works, not about how humans should behave towards one another.
In my personal opinion, science can certainly explore moral questions, but cannot conclusively answer them. We can do polls about what people think, but is it given that what the majority thinks is true? In any other field, one would say no. When people thought the world was flat, or that the Earth, not the Sun was the center of the universe—later, of course, we realized that the Sun isn’t even the center of the universe, which has no center, but merely the center of the solar system, but that’s a tangent—would that majority opinion make it true? No.
Game theorists and others try to model how one can optimally behave in various situations. But if taken as a moral theory, that could easily lead to egoism.
Some claim that what is natural is right, but they also skip the necessary logical step between “is” and “ought”. Rape happens in nature. Does that make it right? No. That is sometimes called the naturalistic fallacy.
This is a super complicated issue that has been debated since Socrates. If you are interested, you can read Plato’s dialogue Euthyphro. Or you can read about the is-ought problem on Wikipedia. The best source, however, is the Stanford Encyclopedia of Philosophy, which is a free encyclopedia peer-reviewed by philosophers. See here, here, here and here. But the Stanford Encyclopedia is rather dense and technical, and perhaps hard to read if you have no previous experience reading analytic philosophy.
Personally, I subscribe to a theory called moral quasi-realism, which was inspired by Hume and by Ludwig Wittgenstein and developed by Simon Blackburn. Blackburn has also written some books aimed at introducing people unfamiliar to philosophy to the field. Quasi-realism allows you to make moral statements without betraying Hume’s Law, but admittedly they have less force than if they could be claimed to be grounded in science.
In general, I have to say this is a very complex question to answer. It’s hard to answer properly without getting too technical, and I think most of the readers of this blog would lose track or patience or get bored quite quickly if I really got into it. Not because they’re dumb, just because this is Tumblr, they are unfamiliar, it’s technical and they might just want to look at pretty pictures or hear the latest in science explained in an understandable, but not dumbed-down way. That is my goal with this blog: to bring science to the people in a way that neither betrays the science by explaining it with half-baked metaphors or overhyping findings which are really just small developments in a field. But also to make it readable and enjoyable for as many people as possible.
Science is fantastic, people! It’s not just pretty pictures of galaxies or neurons or puppies transplanted with genes so they glow in the dark.
But to conclude: No, science can’t answer moral questions. Only explore them.
The Golden Rule, advocated by such luminaries as Jesus and Buddha, is still a good rule of thumb. It’s not scientific, it’s just a basic test to see if you’re being an asshole or not.
This is not scientific advice grounded in peer-reviewed journals, but it’s still damn important: be kind to one another, and as long as people are not hurting anyone else, tolerate them, whether they have the same skin color or the same politics or religion or musical tastes as you or not.