(b. Kirkroads, near Bathgate, Linlithgowshire, Scotland, 10 January 1785; d. Edinburgh, Scotland, 18 November 1857)
The son of Alexander Fleming, a tenant farmer of moderate means, and Catherine Nimmo Fleming, John Fleming completed his studies at the University of Edinburgh in 1805 and was licensed as a minister in the Church of Scotland in 1806. He served in the small parishes of Bressay, Shetland (1808–1810), and Flisk, Fifeshire (1810–1832), and in the larger parish of Clackmannan, near Edinburgh (1832–1834), before becoming professor of natural philosophy at King’s College, Aberdeen, in 1834. When the Free Church broke away in 1843, Fleming joined it; and in 1845 he became professor of natural science at New College (Free Church), Edinburgh. He married Melville Christie in 1813, and they had two sons, of whom only one, Andrew, lived to adulthood.
A member of the Wernerian Natural History Society from its founding in 1808, Fleming was elected a fellow of the Royal Society of Edinburgh in 1814. He was later a member of the Royal Physical Society of Edinburgh and other scientific societies. After 1834 he began to suffer spells of ill health, which became more frequent until his death. Fleming’s disposition tended to be grave and critical—what humor he had was often sarcastic—but his kindness and honesty were appreciated by those who knew him.
Fleming’s scientific career may be divided into four periods: a Wernerian period (1808–1820), when he was a disciple of Robert Jameson; a period of productivity and controversy (1820–1832); a period of reduced productivity (1832–1845), due to the pressure of his duties at Clackmannan and Aberdeen; and a period of renewed activity at New College (1845–1857).
Regarded as Scotland’s foremost zoologist as early as 1815, Fleming was concerned largely with the description and classification of freshwater and marine invertebrates. In his Philosophy of Zoology (1822), he advocated the binary or dichotomous system of classification, in which a twofold division is made at every level into those animals that possess a certain character and those that do not, a different character being used at each level. Despite his claim that this system was a practical approach to a true natural system, little notice was taken of it by other zoologists because of its artificiality. His History of British Animals (1828) was a detailed description and classification of the British fauna, although it omitted the insects, which were supposed to be covered in a succeeding volume that never appeared. The book was noteworthy for its inclusion of fossil species and for its application of the binary system throughout.
Although Fleming always had a low opinion of James Hutton’s theory of the earth because of its plutonism and because he considered Hutton an incompetent mineralogist, he did agree with the Huttonians that knowledge of the present was the key to the past. Thus, in the Philosophy of Zoology one can find the following views that Fleming’s friend, Charles Lyell, would later develop as a part of his uniformitarian attack on catastrophism: (1) an emphasis on noncatastrophic causes of the extinction of species, particularly (in Fleming’s case) man’s activities; (2) a tendency to reject the evidence for a progressive increase in the complexity and perfection of life during geologic time; (3) the idea that world climate might have been affected by an increase in the amount of land during the course of geologic history; and (4) the rejection of the theory of an originally molten earth that has slowly cooled down.
From 1824 to 1826, with Jameson’s secret encouragement, Fleming engaged in a controversy with William Buckland in which he showed that Buckland’s theory of a violent deluge contradicted both the Bible and the scientific evidence. Fleming argued that the Bible represented the deluge as nonviolent, and he attributed the so-called “diluvial” phenomena to local river floods, the bursting of lakes, and uprisings of the sea. In a controversy with William Conybeare in 1829, Fleming disputed the fossil evidence for a warmer climate in the past, insisting that our knowledge of the habits of an existing species can tell us nothing about the behavior of a similar, but not identical, fossil species, since every species is fixed and unique in its behavior.
Fleming had argued in his controversy with Buckland that there must be free inquiry in science without regard for the Bible, yet in his History of British Animals he adopted a scheme of reconciliation between geology and Genesis that was originally proposed by a friend, the Reverend Thomas Chalmers, on the basis of Cuvier’s idea of successive creations. This theory, which was elaborated by Fleming in his Lithology of Edinburgh (1859), assumed that the “pre-Adamic” life had been totally destroyed by some extraordinary cause (probably the darkening of the sun) accompanied by debacles of water rushing over the earth. The species of animals and plants of the present epoch had then been created during the six days (or periods) described in Genesis. Similar revolutions, he believed, had initiated at least five previous epochs in earth history. Thus it can be seen that Fleming rejected Lyell’s uniformitarian views for earth history as a whole. The idea of evolution was, of course, anathema to him, and we find him in 1854 citing Scripture in opposition to it.
Fleming was by nature conservative, reluctant to alter his views once they had been firmly established. The discrediting of neptunism around 1820 only served to reinforce his already skeptical attitude toward geological theory. His contributions to geology were therefore essentially negative—the effective criticism of inadequate theories. His views, which were relatively enlightened in the 1820’s, when they were opposed to the catastrophist excesses of Cuvier and Buckland, were definitely outmoded by the 1850’s. Despite his extensive zoological and paleontological knowledge (he was, for example, the first to discover the remains of fish in the Old Red Sandstone), Fleming had been trained in the old mineralogical school of geology and apparently never fully accepted the new geology, which relied boldly upon paleontological criteria in correlating strata.
I. Original Works. Fleming’s most important works were The Philosophy of Zoology, 2 vols. (Edinburgh, 1822); A History of British Animals (Edinburgh, 1828); and The Lithology of Edinburgh, ed., with a memoir, by Rev. John Duns (Edinburgh, 1859).
A list of Fleming’s works by Alexander Bryson, Transactions of the Royal Society of Edinburg, 22 (1861), 675–680, is fairly complete (129 items, including two, nos. 80 and 109, which are not by Fleming according to W. E. Houghton, ed., The Wellesley Index to Victorian Periodicals, 1824–1900).
The list in the Royal Society of London Catalogue of Scientific Papers (1800–1863), II, contains fifty-three items, of which six are not in Bryson’s list. The Royal Society Catalogue, however, has fuller and sometimes more correct entries, and it usually gives all the journals in which each article appeared. These lists do not cite all the articles by Fleming in the Edinburgh Encyclopaedia, Encyclopaedia Britannica, supp., vol. III (1824), Edinburgh Monthly Review, and New Edinburgh Review.
There are a few of Fleming’s letters still extant, notably several to Lyell at the American Philosophical Society, Philadelphia.
II. Secondary Literature. The memoir by Duns (see above) contains extracts from Fleming’s correspondence. A memoir by Bryson in Transactions of the Royal Society of Edinburgh, 22 (1861), 655–675, emphasizes his scientific work. See also “Scottish Natural Science,” in North British Review, 28 (1858), 39–55, by Duns, which is largely devoted to Fleming.
L. E. Page