Theory and clinical use of probabilities in Germany after Gavarret. Part 2: assessments of the state-of-the-evaluative art

Abstract

The contributions made by German writers discussed in the previous article in this series had not passed unnoticed. A conscientious young medical historian doctor sensed that issues of evaluation and probability were in the air: Julius Petersen (b.1840) of Copenhagen gave a substantiated description of the situation in his Hauptmomente in der geschichtlichen Entwicklung der medicinischen Therapie (Key moments in the historical development of medical therapy, 1877). In 29 pages, he dwelled on Poisson, Gavarret, Louis, Wunderlich and others, and on the numerical method. He quoted Gavarret, rightly (and at length), saying that there was much loose verbiage about probability, whereas only the calculus of probabilities could really help to estimate the worth of mean values (averages). Albeit still far from being perfect, this method was important for future developments (p. 179). Petersen clarified the confusion between Benecke and Vierordt: the former explained the effect of a cure, the latter thought that it was being demonstrated statistically. Again, this was the old debate between rationalism and empiricism. I think we can trust him when he said in the mid1870s that in France, England and Germany polypharmacy and the post hoc ergo propter hoc fallacy prevailed, Louis’s principles were lost sight of, but some British followers of Bacon were still eclectics and indulged in common sense (Petersen, 1877). A young German insider engaged in an overview of the methods available in clinical research, particularly in therapeutics. Friedrich Martius (b.1850), while a military doctor and later an assistant physician at the Berlin Charité University Clinics, published two lengthy articles on the subject: Die Principien der wissenschaftlichen Forschung in der Therapie (The principles of scientific research in therapy, 21 pages, Martius, 1878) and the even more erudite Die numerische Methode (Statistik und Wahrscheinlichkeitsrechnung) mit besonderer Berücksichtigung ihrer Anwendung auf die Medicin (The numerical method [statistics and calculus of probabilities] with special reference to its application in medicine, 41 pages, Martius, 1881). Later he became professor of internal medicine at Rostock and, typically, did not publish any longer on the subject. As Oesterlen and Schweig had done some 30 years previously, Martius begun by clarifying the confused terminology. He analysed the French and German works (Radicke was not mentioned!) by putting them in the wider historical context of the theories of cognition: the term ‘induction’, he wrote, was often used without distinguishing whether ‘logical’, ‘numerical’ or ‘experimental’ induction was meant. Numerical induction he understood as being based on statistics and probability calculus. For, although they had been developed separately, statistics and the calculus of probabilities could be summarised under the common term ‘numerical method’. Indeed, they complemented each other