History of Science and Technology Colloquium

In his Preliminary Discourse on the Study of Natural Philosophy (1830), the astronomer and philosopher J.F.W. Herschel claimed that it was sometimes acceptable to invent a theory by making a "bold leap" to a hypothesis, so long as this hypothesis was then tested deductively. Because of this comment, Herschel has generally been considered a proponent of the "hypothetical-deductive" or "hypothetical" method of science. It has been argued by commentators that because Herschel was well-versed in science, he realized that the science of his day relied on unobservable entities, such as light waves, ethers, and tiny particles of matter; Herschel, it is said, correctly recognized that theoretical science requires a hypothetical method. In my paper, I will show that this interpretation of Herschel is just one of a number of instances in which modern philosophers of science have erred in attributing a hypothetical method to writers of the past. I will demonstrate that Herschel, like these other writers, believed that analogical reasoning was a key part of scientific discovery. Scattered comments about "bold leaps" are meant to refer to instances of analogical inference, not conjectures or guesswork. Herschel, and other misunderstood writers such as Francis Bacon in the seventeenth century and Herschel's friend William Whewell in the nineteenth, believed that analogical inference played a large role in scientific discovery, even for theoretical science. And they were right. Part of the reason for these misinterpretations is historical: commentators have ignored the context of these comments within the work of the writer and within his intellectual and social framework. And part is philosophical: analogical inference is very often overlooked or undervalued as a part of inductive reasoning. I will argue here that, by debunking this "myth" about "bold leaps" in the scientific method proposed in the past, we can learn important lessons for philosophy of science in the present.