Von Haller on hypotheses in natural philosophy
Alberto Vanzo writes…
Typically, the experimental philosophers on whom we focus in this blog promoted experiments and observations, while decrying hypotheses and system-building. This is the case for several experimental physicians, to some of whom we have devoted the last two posts. Their Swiss colleague Albrecht von Haller thought otherwise. He published an apology of hypotheses and systems in 1751.
Von Haller was a novelist, a poet, and an exceptionaly prolific writer on nearly all aspects of human knowledge. He is said to have contributed twelve thousand articles to the Göttingische gelehrte Anzeigen. However, von Haller was mainly employed as an anatomist, physiologist, and naturalist. Like his Scottish colleague Monro I, he had studied in Leyden under Boerhaave. Having achieved Europe-wide fame for his physiological and botanical discoveries, von Haller was called by George II of England, prince-elector of Hanover, to occupy the inaugural chair of medicine, anatomy, botany and surgery at the newly founded University of Göttingen. Göttingen was under the strong influence of British culture throughout the eighteenth century and would later be the main centre of German experimental philosophers. While in Göttingen, von Haller was mainly engaged in his physiological and botanical studies, besides organizing an anatomical theatre, a botanical garden, and other similar institutions.
Haller’s essay, entitled “On the Usefulness of Hypotheses”, was first published as a premise to the German edition of Buffon’s Natural History. It was reprinted posthumously in 1787. Throughout these years, several authors in the German speaking-world endorsed Newton’s radically negative attitude towards hypotheses. For instance, few years after von Haller’s essay the physician Gerard van Swieten — also a pupil of Boerhaave — published a discourse on medicine in which he cried “may hypotheses be banned!”. And in the 1780s, when von Haller’s essay was being reprinted, the anthropologist Johann Karl Wezel proclaimed in broadly Newtonian spirit: “I only relate facts”.
Von Haller was aware of this anti-hypothetical fashion. He starts his essay by describing how naturalists had come to despise hypotheses. With the success of mathematical natural philosophy (the Newtonian form of experimental philosophy that had replaced Baconian natural histories), researchers started to rely (or at least, to claim that they were only relying) on what had been mathematically proven. This happened first in England with Newton, then in Holland with Boerhaave, then in Germany and France with Maupertuis and others.
For Haller, this was not a positive development. Peopled shifted from one excess, namely abusing of hypotheses, to an other, namely rejecting them altogether, while ignoring the virtuous middle way. Yet, while researchers were despising hypotheses, they were relying heavily on them:
- The great advantage of today’s higher mathematics, this dazzling art of measuring the unmeasurable, rests on a mere hypothesis. Newton, the destroyer of arbitrary opinions, was unable to avoid them completely. […] His universal matter, the medium of light, of sound, of the senses, of elasticity — was it not a hypothesis?
Von Haller makes other examples of natural-philosophical hypotheses, in order to highlight
- the true use of hypotheses. They are certainly not the truth, but they lead to it, and I say even more: humans have not found any way that is more successful in leading them to the truth [than hypotheses], and I cannot think of any inventor who did not make use of hypotheses.
What is this “true use of hypotheses”? It is their heuristic use. Hypotheses are claims to be tested by means of experiments and observations. Sets of hypotheses form large-scale systematic pictures that provide purpose and direction to our research. Think for instance of the heuristic value of the corpuscular hypothesis for the experimental activity of the early Royal Society (this is not von Haller’s example). Additionally, hypotheses make possible a public discussion of problems that scientists could not even mention if they were only allowed to talk about were facts, as some experimental philosophers hoped.
These experimental philosophers may reply to von Haller that they do not need to employ hypotheses to achieve those aims. All that is needed are queries. Von Haller would reply that queries are nothing else than hypotheses in disguise. “In fact, Hypotheses raise questions, whose answer we demand from experience, questions that we would not have raised if we did not formulate hypotheses”.
Von Haller was not the only author in the German-speaking world to provide a qualified defense of hypotheses. Christian Wolff before him and Immanuel Kant after him made similar points. However, von Haller was much more engaged in empirical research than either of them. His work seems to me to have been very much in the spirit of experimental philosophy. Finding such an explicit and detailed defense of hypotheses by such an author reminds us that the methodological views of early modern experimentalists were not monolithic and that, even in a strongly anti-hypothetical age, some authors were aware of the benefits of a careful use of hypotheses in the study of nature.
