Herschel, John (1792–1871)

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John Herschel, the son of the astronomer William Herschel, worked in mathematics, chemistry, optics, and solid-state physics; pioneered in photography and instigated the regular use of photography in astronomy; invented blueprints; initiated simultaneous worldwide meteorological observations; introduced the theory of isostasy in geology; and was the world's leading observer-theoretician of double stars and nebulae. His Treatise on Astronomy (1833), continued as Outlines of Astronomy (1849), although deliberately common sense in treatment, was authoritative in content even for professionals until the 1860s. He was England's most famous scientist from 1830 to about 1860.

Herschel's Preliminary Discourse on the Study of Natural Philosophy (1831) was a starting point for his philosophic contemporaries, the more radical (post-Kantian) William Whewell and the more conservative (Humean) J. S. Mill; in fact, many errors were deleted from Mill's Logic in its second edition because Herschel supplied detailed criticisms of the scientific passages in the first edition. Herschel's full position was expressed later, in papers collected as Essays from the Edinburgh and Quarterly Reviews (1857) and Familiar Lectures on Scientific Subjects (1867) and in remarks in his scientific books. His best-known philosophic followers were William Stanley Jevons and James Clerk Maxwell.

In theory of knowledge, Herschel's basic concept was the law of continuity, which for him defined the rationality of a system. In his version of the law, he asserted that scientists observe not continuous phenomena (not even simple extension), but "dotted outlines which the mind fills up." Thus "we assume continuity where we find none." Herschel refused any philosophic solution of this disparity between observation and thought and accepted the harmony of mind with external nature as an ultimate fact, preestablished by God.

Next, he was a "decided disciple of old Boscovich"; matter is "a collection of mathematical pointsmere localization of forces "; and therefore it is foolish to picture kinetic-molecular processes as "the 'clashing together' of 'atoms'" or as the "knocking about of billiard balls." Force as hitherto understood, he pointed out, was always associated with matter, that is, inertia; but in electricity and in the "quasi-undulatory propagation of qualities" we see noninertial agents. So the kind of force presented in theories of mechanics is not primary. More basic physical powers exist, he asserted, but are not yet (1840) understood.

Science should uncover not only laws (formal relations among parameters) but also causes. Causation is not Humean succession but (as in the Scottish commonsense school) is known from our consciousness of effort when we exert force. Causes are not will, however, but the physical intermediaries between will and muscular contraction. These may also exist in connection with inanimate bodies.

This general position is well beyond Roger Joseph Boscovich and Thomas Reid but is not idealistic. It points toward the theory of the conservation of energy, which, however, Herschel did not approve in its 1860 form. He felt that "potential energy" was not a physical reality, but a mere mathematical expression introduced into the theory "to save the truth of its verbal enunciation."

In methodology Herschel was interested in discovery, not in a justification of the process of induction. (Mill's "methods" were derived directly from Herschel's Discourse.) Thus one Herschelian method was "at once to form a bold hypothesis," that is, to guess. Herschel emphasized the central importance of rigorous deduction to confirm hypotheses; it is this which makes science not a craft. One should at all costs avoid specialties of investigation (e.g., chemistry vs. physics), for no actual phenomenon is so divided. Herschel thought that contingency is the most obvious aspect of the universe. Science must grapple with the apparently arbitrary complexities of the actual world, such as sunspot changes, the shapes of nebulae, the variations in terrestrial magnetism, trade winds, and so on, and try to reduce them to scientific laws. It should not content itself with simple general laws concerning force and matter considered in abstraction.

Herschel's contemporary influence was perhaps greatest among working scientists. He gave a reasoned basis for the shift from a purely abstract treatment of physical parameters (as in Joseph-Louis Lagrange) to a belief in the actual existence of the entities used in scientific theories (e.g., the fields of force of his friend Michael Faraday and his admirer Maxwell, which were felt to be actually present in space, not merely mathematical symbols). He upheld the importance of the scientist's feeling for the reality of his constructs. Sheltered by his great authority, scientists pursued their intuitional ideas without worrying about attacks from Humean or other philosophers, or from Evangelical preachers. Herschel, for example, authoritatively established the naturalistic origin of species as a proper subject of investigation for Victorian Englishmen. Young scientists of the period, such as Charles Darwin and Thomas Andrews, admired him extravagantly.

See also Boscovich, Roger Joseph; Causation: Philosophy of Science; Darwin, Charles Robert; Epistemology; Epistemology, History of; Faraday, Michael; Jevons, William Stanley; Maxwell, James Clerk; Mill, John Stuart; Reid, Thomas; Whewell, William.


There are no modern editions of Herschel's works. Recent partial treatments are C. J. Ducasse, "John Herschel's Philosophy of Science," in the American Council of Learned Societies collection, Studies in the History of Culture (Menasha, WI, 1942), reprinted in Theories of Scientific Method, edited by E. H. Madden (Seattle: University of Washington Press, 1960); W. F. Cannon, "The Impact of Uniformitarianism," Proceedings of the American Philosophical Society 105 (1961): 301314; and W. F. Cannon, "John Herschel and the Idea of Science," Journal of the History of Ideas 22 (1961): 215239, containing an error on "will" that has been corrected in the present entry.

Walter F. Cannon (1967)

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Herschel, John (1792–1871)

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