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|Historical Context=In the 17th century, the “method of hypothesis” (i.e. the hypothetico-deductive method) was popular, but by the 1720s and 1730s it had lost its influence and was replaced by slow, careful inductive methods influenced by the success of Newton’s Principia.[[CiteRef::Laudan (1981a)|pp. 9-12]] This view was still largely in effect when John Herschel was born in 1792 into a preeminent English scientific family, his father William being a prominent astronomer who is credited with discovering Uranus. He became one of the most respected scientists of his time, and in 1830s England, “one answer to the question of how to be scientific might be, ‘Be as much like Herschel as possible.’”[[CiteRef::Cannon (1961a)|p. 219]] He excelled in pure mathematics, optics (he was a pioneer in the technology leading to photography), astronomy and botany (among others). The inductive method of the day remains apparent in influencing Herschel’s work, but he deviates from it in notable ways, resulting in him being part of the movement which revived the method of hypothesis. This revival movement began in the mid-1700s with scientists like the David Hartley and George LeSage who put forward physical theories on psychology and on the ether, respectively. Their theories were reliant on unobservable entities, and were criticized at the time not for their substance, but for their epistemological basis.[[CiteRef::Laudan (1981a)|p. 119]] Both fought back against this inductivist attack on their work, particularly LeSage, who proposed his own “method of hypothesis” in a series of philosophical essays, in which he contended that Newton’s work was riddled with hypotheses, contrary to the inductivism of the time.[[CiteRef::Laudan (1981a)|pp. 120-122]] Following LeSage, Jean Senebier, a pioneer of photosynthesis research, advocated for the method of hypothesis in his 1775 ''L’Art d’observer'' (later revised in 1802).[[CiteRef::Laudan (1981a)|p. 14]] Dugald Stewart, a prominent Scottish philosopher and mathematician, wrote similarly to LeSage and Senebier, directly influencing Herschel and William Whewell (a friend and colleague of Herschel’s). This movement was influenced partly by scientific theories developed in the mid-late 18th century like the wave theory of light, the theory of phlogiston, and Franklin’s fluid theory of electricity, each of which hypothesized unobservables to explain observable phenomena.[[CiteRef::Laudan (1981a)|p. 12]] In other words, these hypotheses decidedly did not come from the aforementioned slow and cautious inductive methods. Given the apparent success of at least the wave theory of light, they had to be given some consideration pursued, if not necessarily accepted, as good, accurate scientific theories. And this is where the method of hypothesis, aided by Herschel and his contemporaries/immediate predecessors (such as Whewell, LeSage, Senebier, and Stewart), came back to become the dominant scientific method.[[CiteRef::Laudan (1981a)|p. 14]]

|Criticism=Herschel’s PD was for the most part well-received by his contemporaries, likely in part due to his high standing in the scientific and philosophical community at the time. It was praised not necessarily for its strength of argumentation (after all, Herschel was not a professional philosopher), but for its practical advice and its portrayal of the ideas of an actual practitioner of science. Darwin even cited it as a personal influence in his autobiography and referenced Herschel in the preface to his ''Origin''. Herschel did face some criticism from William Whewell, who commented that Herschel’s departure from pure inductivism could “foster a spirit of gratuitous theorizing, which will misemploy the cultivators of science, and mislead those who learn it through words alone”.[[CiteRef::Whewell (1831)|p. 400]] However, most views along these lines were silenced in the early 20th century with the acceptance of Einstein’s theory of relativity, which was arrived at partly through Whewell’s feared “gratuitous theorizing”. Overall, criticism was limited due to the scientific environment at the time, in which many speculative theories were experiencing experimental success and gaining acceptance.