In Praise of Anecdotal Evidence. In this book I report a number of case histories, and I am often using these to make a point. Some scientific-minded readers may tend to dismiss these stories as merely anecdotal evidence. Please don't do that. Properly designed studies and controlled trials are not the only way to know reality. The bulk of knowledge humankind has accumulated in its history has not been derived from controlled trials. People found that Britain was an island, and how to bake bread, though no properly designed studies on these subjects had been conducted. Medical knowledge begins with case histories, that is, anecdotal evidence. Basic discoveries in medicine: that measles were contagious but left a life-long immunity; that black stools indicated a bleeding from the upper part of the digestive tract; that acute rheumatic fever led to valvular heart disease, and many hundreds of equally important observations, were all based on anecdotal evidence. It was on grounds of purely anecdotal evidence that Dr. Edward Jenner introduced in 1796 his cowpox vaccine, and Dr. William Withering his foxglove therapy (1785); yet Jenner's vaccine saved many millions of lives, and ultimately eradicated smallpox on this planet; and Withering's digitalis has relieved hundreds of thousands of people suffering from heart failure. It is not true that such discoveries could only be made in the 18th century, but are impossible now. We are still able to observe facts. Properly designed studies and controlled trials serve to deepen and verify our knowledge, not to make us blind to what is happening around us.
How Scientific Medicine Has Become. The notion that medicine is being transformed from old guesswork and empiricism into an exact science of "hard facts," laboratory measurement, and statistically significant findings, is partly true and partly based on a mistaken understanding. There has been an abundance of hard facts in traditional clinical medicine, and by no means are all assertions of the new "scientific" medicine hard facts or objective truths. If listening to a patient's heart we hear a very loud first heart sound preceded by a coarse murmur, and the second heart sound is followed by an additional "snap," so that the whole tune resembles a quail's call, we know that the patient has a valvular heart disease, namely, a narrowing of the orifice between the left atrium and the left ventricle (mitral stenosis), and this is a harder fact than the "scientific" measurement of the orifice's surface based on catheterization data since the latter method has many pitfalls: low flow, leaking valve, beat-to-beat variation, or failure to wedge the catheter into a small pulmonary blood vessel, all introduce errors to this determination. (87)
The new scientific medicine is not even free of some patent nonsense. The electrocardiographic diagnosis of "anterior" myocardial infarction is still based on the ingenious but mistaken "electrical window" theory. As a result, the localization and extension of the infarction, as determined from the ECG, prove wrong at the post-mortem in more than half the cases. (88)
What is a "Hard Fact"? The noted Polish-Jewish serologist Dr. Ludwig Fleck published in the 1930s a book in German on "The origins and development of a scientific fact." Many years later his theories gained some popularity among American historians of science, (89) Fleck, indeed, was a precursor of present day "post-modernism." In his view, a "scientific fact" was the result of a gradual process during which the circles having a say in science developed a conceptual apparatus and a vocabulary needed to formulate the new truth. I do not subscribe to Fleck's view and think that his use of language confused a natural phenomenon with its discovery and its acknowledgment by the scientific community. But I do find the uncritical faith in the self-contained existence of "hard scientific facts" a bit naive.
Hard as a Fact May Be, It Takes a Human Being to Perceive It. …