In reply to Longhorn's comments:
Yes, you bring up several important issues that need to be addressed.
First, the MD/PhD dual degree is a unique program designed to generate physician-scientists who investigate basic problems to further our understanding of disease in order to ultimately be able to better treat patients.
The MD/PhD is unique and much different than just an MD or an MD/MS. In completing the Ph.D., you gain significant experience in research, and really learn how to do science to the point that you are qualified to be an independent investigator. This means having an understanding of basic problems and formulating strategies or approaches to tackle them. The training in an MS program, while valuable, is not as extensive as a Ph.D. program. The requirements are different and less is expected in the way of scientific accomplishment. If you just go the MD route, you miss out on the graduate school experience and all the learning that takes place there.
Medical school and graduate school are very different animals. In the former, the focus is on acquiring a encylopedic-like education that gives you breadth of medical knowledge and allows you to approach patient's health problems. Given the vast amount of information that must be taught, relatively little time is spent showing data or critically analyzing results or supposed "facts". Instead, you are expected to just digest the information, with little thinking involved.
In graduate school, by contrast, the focus is less on breadth and more on delving into specific topics in order to develop critical thinking skills and to learn how to formulate questions and approaches for answering them. Students are encouraged to question material presented. In my medical school classes, very rarely does anyone do this--in fact it is often discouraged. However, in graduate classes I have taken, professors encourage us to ask questions, dispute unsupported assertions, and otherwise think like scientists. Graduate program requirements vary, but usually include coursework, teaching experience, research rotations, journal clubs, retreats, an oral examination, and of course the thesis defense. This provides extensive training in learning to be a scientist, which you simply do not get in medical school alone.
Another issue you bring up is that of MDs doing bench research. While they are certainly capable of running a lab eventually, the problem is that MDs often have a greater initial learning curve--it takes them years during postdoctoral fellowship work to get themselves up to speed. In addition, the number of MDs going into research has dropped significantly over the past years. MD/PhD graduates are much more likely to go into research careers than their MD counterparts. Furthermore, MDs are as a group less successful than MD/PhDs at obtaining academic positions, research funding, and other measures of scientific success. While this doesn't mean that MDs can't do research (there are many examples that highlight the contrary), it does shed light on some of the advantages of the MD/PhD pathway.
While it may seem like medicine and science have many similarities, they are actually quite different worlds, with different types of people, philosophies, ways of thinking and communicating, etc. MD/PhDs provide an essential link or bridge between these worlds, because they have the breadth of clinical knowledge provided by medical school and the scientific know-how gained through graduate training. I have seen many examples of MD/PhDs acting as that bridge and directly integrating their clinical practice and basic research interests. It's not easy to do by a longshot, but it is at least possible.
I agree with your comments regarding the necessity for humanity in medicine. One certainly wouldn't want to approach patients from a purely "scientific" perspective, which has the connotation of being cold, heartless, and only interested in experiments. I think what airborne was getting at is that MD/PhDs are already trained to think critically and use good reasoning skills when they hit the wards. They are also better able to search the literature and find support for therapies and alternatives. Despite the rise of "evidence based medicine", there are still many echos of the old days in which things are done a certain way because of tradition. Until put to the test under randomized controlled trials (which are in themselves a sort of experimental paradigm), a particular course of action may only serve to propagate the status quo and in fact not offer the best possible medical care. Case in point: the recent NEJM article that showed a type of athroscopic knee surgery is no more effective than a sham surgery (I have no idea how they were able to get that one past the human ethics board...).
In shadowing my former research advisor (who is an MD/PhD), I have often observed him bring research to the bedside. An example is being able to discuss the latest advances in our knowlege of certain disorders and offer some hope that potential therapies are up and coming. He also goes the other way and brings his clinical practice to the bench in studying the genetics of certain disorders. What amazes me the most is that despite the profound scientific knowledge and training, he is also a very empathic physician who is able to reassure patients and provide support despite the presently incurable diseases that many of them have.
I hope this has helped answer some of your questions. If you have additional ones, I'd be happy to discuss.
