I submit, however, that such a characterization is an error.
It is not a slur on the profession or its practitioners to say this, particularly once one understands that science is not the only, or only worthy, or even the most prominent form of reasoned inquiry that people can and do engage in. Furthermore, it is not a slur to say something that is simply true.
Classifying things is always a tricky matter, because there will often be outliers that manage to squirm free of even the most careful definition. Nevertheless, I am going to propose a set of classifications that, while undoubtedly less than perfect, are nevertheless fairly useful particularly from the logical point of view. (That is, of practical value in terms of inquiry into inquiry.)
The classifications/definitions I propose are around the nature of the scientist, the engineer and the technician. This involves no claim as to the fundamental value &/or dignity of these persons and their respective activities, particularly as the logical (see ) aspects of their activities are in many ways the same. Where they differ is in the topics which command their attention and toward which their inquiries are directed.
SCIENTIST: One whose inquiries are directed toward the discovery of new facts.
ENGINEER: One whose inquiries are directed toward the new applications of established facts.
TECHNICIAN: One whose inquiries are directed toward the maintenance of established facts.
Once again, I believe these definitions are substantive and useful. Moreover, by these definitions it becomes clear that medical doctors are not – in general! – scientists, nor are they typically engineers. Medical doctors are, as a rule, technicians.
MDs can be scientists; for example, some of them are also engaged in fundamental research on various aspects of disease &/or the human body. But one has to say “also” in the above, because such research is not their primary function as an MD. Some of them are engineers as well as MDs: they may be engaged in the development of new drugs or new diagnostic equipment &/or techniques. In the first case they are also doing research into new facts, in the second into new applications of established facts.
But these activities are not representative of their activities and training as Medical Doctors.
An MD qua MD is engaging a pre-existing system (as in, your “body”) and looking to perform various maintenance activities. You are sick, something hurts, this is broken; no new facts are being discovered, nor are the existing facts being applied in novel manners. Rather, existing facts are being taken and maintenance is being performed. Or perhaps nothing is wrong, and you are just there fore a check-up? That is, you are engaged in preventative maintenance: check the oil, flush the radiator, shove a scope up your … never mind.
Regardless, in terms of “type” or “kind,” these are exactly the types and kinds of things that technicians do. The specifics differ, or course; but they always differ. What my AAA auto mechanic does – specifically – qua auto mechanic is different from what I specifically did as a networked PC technician, is different from what an MD specifically does qua MD. But generically (that is, as a genre) all are engaged in paradigmatically technician types of activities and inquiries.
And by the bye, if you really want to know, if you absolutely must ask, which of the above three classified activities is genuinely the most important, the one most deserving of dignity, the one most truly to be valorized, it is the technician. The reason for this is painfully obvious: it is the technician who is engaged in maintenance, and there can be no civilization in the absence of maintenance (thank you, Patrick Mulholland). Civilized societies have endured for centuries – even millenia – in the absence of science and even any substantive engineering. But no civilization has lasted long enough to even pronounce the word in the absence of maintenance. And such is the responsibility of technicians.
Kipling wrote a poem once for the “Calling of the Engineer;” but the Sons of Martha are the technicians who
“ … take the buffet and cushion the shock.
It is their care that the gear engages; it is their care that the switches lock”
 http://www.merriam-webster.com/dictionary/outlier. For example, my use of “outlier” here is not strictly correct. Yet the analogy makes perfect sense and should cause difficulty for none but the most abusive purist http://www.westegg.com/nash/purist.html.
 http://www.science20.com/inquiry_inquiry/logic_inquiry. Some day I'll stop citing myself on this, probably the same day I achieve genuine enlightenment and my ego dissolves into The One. Look upon this as your personal invitation to hold your breath ...
 If you know him, you don't need to ask. If you need to ask, don't bother.