Here are a few thoughts about what I've learned from interdisciplinary research.
The more interdisciplinary investigation I do, the clearer it becomes that different disciplines have quite different standards for evidence and argument. Some very traditional analytical philosophy papers on happiness (or whatever) are next to useless, so thoughtless are they, despite their impressive dialectical rigor, in the assumption that philosophers' intuitions about the meanings of words, or about our judgments in counterfactual cases, is any kind of reliable guide to truth. Thankfully, this is dying in philosophy. Economists are exceedingly careful about their formalisms, but exceedingly careless about what their formalisms are supposed to be about. Psychologists are (well some of them) very careful about experimental design, on one level. But they are often stunningly naive about the interpretation of the data they have gathered. It is perhaps my own disciplinary prejudice, and perhaps I am being self-serving, but I find that the most enlightening work is often by analytically trained philosophers who are skeptical of traditional analytical methods, and apply their diaectical and analytic skills to the interpretation of scientific results. I'm thinking of philosophers like Daniel Dennett, Stephen Stich, the Churchlands, Kim Sterelny, Paul Griffiths, Andy Clark, Jesse Prinz, David Buller, J.D. Trout, etc. There are a bunch of philosophers of biology and physics that one could add here, but they don't leap to my mind, since those aren't my areas. But I think it's worth pointing out that philosophy and philosophical training really are good for the advancement of real knowledge. And I think we're going see more and more philosophers, armed with a kind of conceptual training that scientists do not normally get, making the transition into primary empirical research, and making major contributions. Here for example is a paper of U of Maryland philosophy professor Chris Cherniak. Where did the “philosophy” go? Who cares!
I think we see similar value-adds from other disciplinary fusions. Economists like Kevin McCabe who have moved into neuroscience are making real contributions to neuroscience as well as economics. It is getting increasingly difficult to tell the difference between some forms of political science and economics. This kind of convergence is very, very good. Despite the stupid institutional impediments caused by the departmental structure of universities, we're on a track to see the resurgence of the old fashioned “moral sciences.” It is getting and harder harder to tell the difference between philosophy, psychology, neuroscience, economics, political science, and the worthwhile branches of anthropology and sociology. There is considerable value in disciplinary differences in the precise way questions are tackled. But there is even greater value in the fact that all these disciplines are increasingly tackling overlapping sets of questions with increasingly compatible intellectual tools.