I think that's the wrong question. It frames the matter in terms of Science (hurrah for rationality!) vs. Conservatives (p*l*t*c*lly motivated bias, boo, hiss!), and suddenly the entirety of what might be said on the matter is condensed down into two isolated points ready-labelled as True and False.
Why conservatives, anyway? It's just as easy to hand-wring it from a "liberal" point of view. (The quotes to indicate that I am not au fait with American political terminology and am not entirely sure what was intended by "conservative".)
I was afraid the grandparent comment would sound too adversarial. Let me explain myself. Many politically conservative Americans (particularly in the Religious Right) are fond of making claims similar to the question Wei Dai asks in the original post — they claim that understanding the way people work in a material universe makes empathy impossible, or something. But I've never heard a convincing argument for it; most of these people are substance dualists.
On the other hand, many politically liberal Americans (particularly New Age types) are fond of repeat...
steven0461 (comment under "Preference For (Many) Future Worlds"):
Yvain (Behaviorism: Beware Anthropomorphizing Humans):
Eliezer (Sympathetic Minds):
So, what if, the more we understand something, the less we tend to anthropomorphize it, and the less we empathize/sympathize with it? See this post for some possible examples of this. Or consider Yvain's blue-minimizing robot. At first we might empathize or even sympathize with its apparent goal of minimizing blue, at least until we understand that it's just a dumb program. We still sympathize with the predicament of the human-level side module inside that robot, but maybe only until we can understand it as something besides a "human level intelligence"? Should we keep carrying forward behaviorism's program of de-anthropomorphizing humans, knowing that it might (or probably will) reduce our level of empathy/sympathy towards others?