Can you explain the differing roles of observation and imagination in the work of Dr. Semmelweis?

The role of observation in scientific method in general is often exaggerated. The author of the Semmelweis article, for example, describes the "narrow inductivist conception of scientific enquiry" which starts off by emphasizing the need to record all the facts without any kind of selectivity. But that is impossible because what facts are relevant completely depends upon background hypotheses. Semmelweis would not have noted the possible importance of the priest walking through the ward, for example, unless he had some kind of psychological hypothesis in mind. Indeed, all the facts he observed were relevant to some hypothesis which directed his attention to them.

Observable facts, therefore, are dependent on background hypotheses. So hypotheses are not derived from the facts in a straightforward way. Where do they come from then? The author suggests that hypotheses are derived from guesses, hunches and creative imagination or invention. In that respect, science is as imaginative as art. Of course, this does not deny that science lacks rigorous constraints to the imagination. For one thing, Semmelweis would not have been able to detect the significance of his colleagues death without the preparation his analyses of childbed fever victims had provided. The "dead end" hypotheses were not useless because they allowed him to accumulate a good sense for the pathology of the disease and hence recognize it when it appeared in a male victim. His imagination was constrained and focused by previous observation.

Secondly, Semmelweis' discovery of the solution to his problem might have been rooted in imagination. Yet the verification or corroboration of his hypothesis involved the methodical meshing of his alleged discovery with pre-existing truths, new facts and experimental reiteration. The procedures of corroboration are a defining feature of science as distinguished from the realm of imaginative art.

Why might it be said the Dr. Semmelweis did not really discover the cause of childbed fever?

Semmelweis discovered that if doctors disinfected their hands thoroughly after performing autopsies then the incidence of childbed fever plummeted in the women whose babies they delivered shortly afterwards. He concluded that "cadaveric matter" caused the disease. This was proved wrong after a doctor caused the fever in women after delivering a baby with hands just used to examine a patient with a "festering wound." So he widened his hypothesis to include all "putrid matter." And since this entailed disinfecting one's hands after pretty well any medical examination, this conclusion was good enough in practice -- many women's lives were saved.

This practical effect, however, did not mean Semmelweis had discovered what we would now call the "cause" of childbed fever. For Semmelweis had no knowledge whatsoever of "germs" or "microbial agents." It was only when Louis Pasteur "discovered" those entities that scientists really knew what caused the fever. For germs were the medium of infection -- destroyed with the process of disinfection. Thomas Kuhn's way of putting this was that Semmelweis operated outside the modern "paradigm" of medicine.

The very idea of a microbial agent is built into this paradigm which also includes ways of talking, various means of instrumentation, connections to similar concepts (such as viruses, vacines, antibiotics) etc.  We often think that "discovering the cause" of something is a matter of methodically observing the facts and straightforwardly drawing conclusions. As we've seen above that is not the case. Thomas Kuhn goes further by emphasizing that all facts are "theory laden" -- a fact is only a fact within a specific paradigm. In that sense, then, Semmelweis could not have discovered the cause because he was not in a position to conceive the very "fact" that was at issue.

Bonus Question: In the article handed out in class, Robert Root-Bernstein points to some alleged anomalies within the standard theory of AIDS. His argument is that a new theory of AIDS must be devised since these anomalies can never be explained with the theory that HIV (and only HIV) causes AIDS. Pick ONE of the (following) alleged anomalies and in a paragraph summarize a way of fitting it into the standard theory. Some of you might be able to do this simply from your own understanding of the theory but others might want to "research" the conventional way of explaining one of the anomalies on the WWW (where this issue is well dealt with). You can also ask someone with knowledge of the subject to help you out. My main intention is simply to get you to express in writing a response from the point of view of the established theory. Hand in your paragraph in class on November 18 (or email it to me before that class) and you can earn 5 bonus marks on your Christmas test. (Earn even more bonus marks by checking out the topic we will be starting on November 18.)

1) Possible AIDS cases can be traced as far back as 1932 and there is a documented case in 1968. This data is anomalous if the HIV virus was transferred to the Western hemispher around 1978 (as the standard theory claims).
2) Based on the standard theory, the medical establishment originally predicted that HIV was due to cut through the heterosexual population North America with an epidemic of AIDS, but that never happened. Even heterosexual prostitutes (except those who were/are drug users) did not incur an epidemic of AIDS. In Africa, on the other hand, heterosexuals have been ravaged by AIDS. All these trends work against the hypothesis of one cause -- HIV -- of AIDS.
3) The standard view is that HIV is the necessary and sufficient cause of AIDS. Yet there exist AIDS sufferers who are not infected with HIV which means it is not a necessary cause. And there are people who have been exposed to HIV who have not come down with AIDS which proves that it is not a sufficient cause since the risk of AIDS depends partly on the host's immune defenses, behavior and environment. 
4) There is a huge and medically unprecedented variation in time between HIV infection and death from AIDS. Whereas if HIV is the sole cause of AIDS this should not be the case.

OR If you find yourself increasingly skeptical about the established view of AIDS, and optional way of gaining the bonus marks is to express an anomaly that I have not listed above. Whether you are more inclined to the establishment or skeptical view, the links listed below might be of help.