Claude Bernard - Introduction To The Study of Experimental Medicine

Introduction To The Study of Experimental Medicine

In his major discourse on scientific method, An Introduction to the Study of Experimental Medicine (1865), Claude Bernard describes what makes a scientific theory good and what makes a scientist important, a true discoverer. Unlike many scientific writers of his time, Bernard writes about his own experiments and thoughts, and uses the first person.

Known and Unknown. What makes a scientist important, he states, is how well he or she has penetrated into the unknown. In areas of science where the facts are known to everyone, all scientists are more or less equal—we cannot know who is great. But in the area of science that is still obscure and unknown the great are recognized: “They are marked by ideas which light up phenomena hitherto obscure and carry science forward”.

Authority vs. Observation. It is through the experimental method that science is carried forward—not through uncritically accepting the authority of academic or scholastic sources. In the experimental method, observable reality is our only authority. Bernard writes with scientific fervor:

”When we meet a fact which contradicts a prevailing theory, we must accept the fact and abandon the theory, even when the theory is supported by great names and generally accepted”

Induction and Deduction. Experimental science is a constant interchange between theory and fact, induction and deduction. Induction, reasoning from the particular to the general, and deduction, or reasoning from the general to the particular, are never truly separate. A general theory and our theoretical deductions from it must be tested with specific experiments designed to confirm or deny their truth; while these particular experiments may lead us to formulate new theories.

Cause and Effect. The scientist tries to determine the relation of cause and effect. This is true for all sciences: the goal is to connect a “natural phenomenon” with its “immediate cause.” We formulate hypotheses elucidating, as we see it, the relation of cause and effect for particular phenomena. We test the hypotheses. And when an hypothesis is proved, it is a scientific theory. “Before that we have only groping and empiricism”

Verification and Disproof. Bernard explains what makes a theory good or bad scientifically:

“Theories are only hypotheses, verified by more or less numerous facts. Those verified by the most facts are the best, but even then they are never final, never to be absolutely believed.”

When have we verified that we have found a cause? Bernard states:

Indeed, proof that a given condition always precedes or accompanies a phenomenon does not warrant concluding with certainty that a given condition is the immediate cause of that phenomenon. It must still be established that when this condition is removed, the phenomenon will no longer appear….

We must always try to disprove our own theories. “We can solidly settle our ideas only by trying to destroy our own conclusions by counter-experiments” (p. 56). What is observably true is the only authority. If through experiment, you contradict your own conclusions—you must accept the contradiction—but only on one condition: that the contradiction is PROVED.

Determinism and Averages. In the study of disease, “the real and effective cause of a disease must be constant and determined, that is, unique; anything else would be a denial of science in medicine.” In fact, a “very frequent application of mathematics to biology the use of averages”—that is, statistics—which may give only “apparent accuracy.” Sometimes averages do not give the kind of information needed to save lives. For example:

A great surgeon performs operations for stone by a single method; later he makes a statistical summary of deaths and recoveries, and he concludes from these statistics that the mortality law for this operation is two out of five. Well, I say that this ratio means literally nothing scientifically and gives us no certainty in performing the next operation; for we do not know whether the next case will be among the recoveries or the deaths. What really should be done, instead of gathering facts empirically, is to study them more accurately, each in its special determinism….to discover in them the cause of mortal accidents so as to master the cause and avoid the accidents.

Although the application of mathematics to every aspect of science is its ultimate goal, biology is still too complex and poorly understood. Therefore, for now the goal of medical science should be to discover all the new facts possible. Qualitative analysis must always precede quantitative analysis.

Truth vs. Falsification. The “philosophic spirit,” writes Bernard, is always active in its desire for truth. It stimulates a “kind of thirst for the unknown” which ennobles and enlivens science—where, as experimenters, we need “only to stand face to face with nature” The minds that are great “are never self-satisfied, but still continue to strive” Among the great minds he names Joseph Priestley and Blaise Pascal.

Meanwhile, there are those whose “minds are bound and cramped” They oppose discovering the unknown (which “is generally an unforeseen relation not included in theory”) because they do not want to discover anything that might disprove their own theories. Bernard calls them “despisers of their fellows” and says “the dominant idea of these despisers of their fellows is to find others’ theories faulty and try to contradict them” They are deceptive, for in their experiments they report only results that make their theories seem correct and suppress results that support their rivals. In this way, they “falsify science and the facts”:

They make poor observations, because they choose among the results of their experiments only what suits their object, neglecting whatever is unrelated to it and carefully setting aside everything which might tend toward the idea they wish to combat.

Discovering vs. Despising. The “despisers of their fellows” lack the “ardent desire for knowledge” that the true scientific spirit will always have—and so the progress of science will never be stopped by them. Bernard writes:

Ardent desire for knowledge, in fact, is the one motive attracting and supporting investigators in their efforts; and just this knowledge, really grasped and yet always flying before them, becomes at once their sole torment and their sole happiness….A man of science rises ever, in seeking truth; and if he never finds it in its wholeness, he discovers nevertheless very significant fragments; and these fragments of universal truth are precisely what constitutes science.