Introduction
John Frederick William Herschel (1792-1871) was an important 19th Century scientist, arguably the most important. (I currently put William Whewell and Herschel on nearly the same footing, with Whewell having a slight edge.) He studied and made applications to the fields of astronomy, mathematics, chemistry, botany, and electricity. He was also one of the first modern "philosophers of science," and an advocate of the use of inductive reasoning in scientific investigations, particularly a version of Francis Bacon's method of induction, informed by the discoveries of science since the early 17th Century (Bacon died in 1626). To promote and encourage the activities of the "men of science," Herschel published the work A Preliminary Discourse on the Study of Natural Philosophy (1830), a treatise on the scientific method, detailing the elements of science, scientific subjects that had been and were being studied, and the procedures that a good man of science should utilize. (This book would be influential for many later scientists, notably Charles Darwin.) Most importantly, Herschel proposed in this work an enhancement of Francis Bacon's philosophy of induction, discussing both the nature of inductive reasoning and the value that should be placed upon it in science. Indeed, the very progression of science from the state of pre-science speculations and collections of facts is a progression of inductions, Herschel would remind us.
This three part essay will detail the elements and rules of Herschel's view of induction, starting with his empiricist view of experience being the source of all knowledge, working our way through his rules for inductive reasoning and ways for verifying inductions made, and the role of analogy, hypothesis, and the complimentary relation of induction and deduction in science. As a result, it isn't a complete discussion of all the important points about science made by Herschel in his Preliminary Discourse, such as the role of precise measurement in describing laws of nature, and I would suggest that the reader takes some time to read the book itself.