Here’s PZ Myers’s take on the issue:
Can science provide a morality to change the world?
Science merely describes what is, not what should be, and it also takes a rather universal view: science as science takes no sides on matters relevant to a particular species, and would not say that an ape is more important than a mouse is more important than a rock. Don’t ask science to tell you what to do when making some fine-grained moral decision, because that is not what science is good at.
What science is, is a policeman of the truth. What it’s very good at is telling you when a moral decision is being made badly, in opposition to the facts. If you try to claim that homosexuality is wrong because it is unnatural, science can provide you a long list of animals that practice homosexuality freely, naturally, and with no ill consequences. If you try to claim that abortion is bad because it has horrible physiological consequences to pregnant women, science will provide you with the evidence that it does no such thing, and also that childbirth is far more physiologically debilitating.
However, I would suggest that science would also concede that we as a species ought to support a particular moral philosophy, not because it is objectively superior, but because it is subjectively the proper emphasis of humanity…and that philosophy is humanism. In the same way, of course, we’d also suggest that cephalopods would ideally follow the precepts of cephalopodism.
So don’t look to science for a moral philosophy: look to humanism. Humanism says that we should strive to maximize the long-term welfare and happiness of humans; that we should look to ourselves, not to imaginary beings in the sky or to the imperatives written down in old books, to aspire to something better, something more coherent and successful at promoting our existence on the planet.
How will we motivate people, and with what moral paradigm to change the world?
As I’ve said repeatedly, science doesn’t provide a morality. What it does provide, and what I optimistically and subjectively think will motivate people, is that it provides rigor and a path to the truth of the world. I know, I could be cynical and suggest that what people really want is delusions, distractions, and reassurances to help them hide away from reality — but what I’ve noticed is that people who accept reality seem to be better able to deal with it, and are often happier and more content. And further, they are better prepared to change the actual world, rather than burying themselves deeper in their fantasies.
In the comments, Myers adds that he’s intrigued but not entirely convinced by Sam Harris’s argument that science can provide a moral framework; he’ll wait to read Harris’s forthcoming book (which I look forward to as well). But he does see science as, at the very least, a matchless tool for helping us arrive at better moral answers. Interesting that he puts the emphasis on humanism as the ideal moral philosophy. I don’t disagree, but after having read Tim Ferris’s exploration of the intimate connection between science and liberal values, I’m willing to seriously entertain the idea that the social and intellectual conditions demanded by scientific inquiry foster many of the principles that humanists cherish. Or am I confusing the chicken and the egg? Food for thought.