Humphry Davy and the Problem of Analogy

Abstract

Andrews Analogy, the comparison of one set of relations to another, was essential to Humphry Davy's understanding of chemistry. Throughout his career, Davy used analogical reasoning to direct and to interpret his experimental analyses of the chemical reactions between substances. In his writing, he deployed analogies to organise and to explain his theories about the relations between physical processes and between the properties of different chemical elements and compounds. But Davy also regularly expressed two concerns about analogical comparison: first, that it was founded not on the rational interpretation of facts but on imaginative speculation; and second, that it was a kind of rhetoric, the persuasiveness of which depended not on material evidence but on misleading figures of speech. This article discusses the influences that informed Davy's ambivalent assessment of the value of analogy, and it examines the distinct yet overlapping ways in which this assessment was expressed in his notebooks, his lectures and treatises on chemistry, his philosophical writings, and his poetry. Humphry Davy's views on analogy are summarised in a notebook that he used at the start of his career, in or before 1800. In some "Observations Relating to Existence," one of several fragmentary essays written in the notebook, Davy announces that: All that we can hope for in physical & metaphysical science ie the science of nature & man is the discovery of new facts & of new expressions of old facts.-By means of our immensely powerful instrument of language we are capable not only of reasoning upon known & common things but likewise by making use of analogies & the 2 analytical method of reasoning upon unknown things the data being known things-it is from the extension of this reasoning to too great an extent that absurd & ridiculous systems of all kinds have been formed. 1 The conjunction of analytical reasoning and analogical thinking, Davy claims, is the basis not just of chemistry but of "science" in its broadest sense, the investigation of "nature & man" which uses "known things" to theorise, discover, and verify "unknown things." But he also places limits on the legitimate scope of scientific knowledge, warning that, if pushed "to too great an extent," this mode of enquiry results not in "new facts" but in "absurd & ridiculous systems," theories with no concrete foundation. He voices a similar reservation, about analogical thinking specifically, in his "Elucidations of Speculative Philosophy" in the same notebook: "The man of Genius must be acquainted with human nature & his acquaintance must be founded not upon bare analogy; but upon an accurate observation of men." 2 Analogies differ from other kinds of comparison because they identify correspondences not between things themselves but between their respective relations to their constituent parts, to their characteristics, or to other things. Analogy was a key part of the intellectual framework of Davy's chemistry, helping him to classify elements and compounds on the basis of si...

Analogy and Composition in Early Nineteenth-Century Chemistry The Case of Aluminium

“…"The body of natural science… consists of facts; its governing spirit is analogythe relation or resemblance of facts by which its different parts are connected, arranged, and employed, either for popular use, or for new speculative improvements". 1 For Davy and his colleagues, analogy was one of the key processes by which the mind identified patterns in nature in order to formulate general propositions (Tate 2019). Due in part to the influence of the Scottish philosopher David Hume , whose problem of induction haunted scientific thought, analogy took up an important place in their publications.…”