PEARSON, KARL
(1857–1936)

Karl Pearson, a British scientist and philosopher of science, was born in London. He studied mathematics at King's College, Cambridge, where he became acquainted with James Clerk Maxwell, Sir George Stokes, and Isaac Todhunter and developed an interest in history, religion, and philosophy. He became a fellow of his college in 1880 and also studied law at Heidelberg and Berlin. Although he was called to the bar in 1881, he never practiced law. In 1884, at the age of twenty-seven, he was appointed to the chair of applied mathematics and mechanics at University College, London, a post that he held until 1911. For part of this time he also held a lectureship in geometry at Gresham College, London, where he developed his ideas in the philosophy of science for a popular audience. Through his friend Francis Galton he became interested in statistical problems in the biological sciences, helped to lay the foundations of modern statistical theory and biometry, and, in 1901, with Galton and Weldon, founded the journal Biometrika. In 1896 he was elected a fellow of the Royal Society and in 1911 he was appointed to the new chair of eugenics at University College. Pearson was an enthusiastic socialist and humanist. He retired in 1933 and died three years later.

Pearson published many scientific papers, as well as essays on most of the subjects in which he was interested. His philosophical work is contained mainly in The Grammar of Science (1892) and The Ethic of Freethought (1888), a collection of essays and lectures. He is usually regarded as an important early figure in modern positivism, but his contribution in this field has perhaps been overrated. Much of his work derives from that of Ernst Mach.

He accepted and developed Mach's sensationalist, antimetaphysical standpoint, but he was not afraid to talk with approval of "a sound idealism" replacing "the crude materialism" of earlier physics. His concern was to emphasize the social background of science and to urge that good citizenship demanded the application of the scientific habit of mind to everyday living. He appears to have regarded this as a large part of the justification of scientific activity, but he also held that science "justifies itself in its methods." Like Mach he dwelt on "the unity of science," which depends upon its method rather than upon its material. This method, based as it is upon verification, rules out metaphysics. The metaphysician is a poet, who does no harm so long as he is recognized as such, but he is often taken to be something more. According to Pearson, an acceptable moral theory is more likely to develop from the experiments of the biologist than from the speculations of the philosopher.

He saw scientific laws as brief formulas representing complex relationships between many phenomena. Their "discovery" is the work of a creative but disciplined imagination; they are products of the human mind. Following Lloyd Morgan, he said that an external object is a construct; that is, "a combination of immediate with past or stored sense-impressions." He asserted, mysteriously and unsatisfactorily, that the distinction between real objects and imaginary ones is that only the real objects depend upon immediate sense impressions.

A fundamental distinction in his work is that between perception, the "physical association" of stored sense impressions, and conception, their "mental association." This appears to mean that perception is merely the copresentation of impressions, while conception is the "recognition" of relations. But the physical and the psychical differ only in degree, not in kind, because both physics and psychology deal with relations between sense impressions, although from different standpoints. On the whole, human brains work in the same way, and thus one receives the same sense impressions and forms the same constructs as another. This ensures the universal validity of science. The field of study of the various sciences is, in fact, immediate sense impressions; these are the phenomena that scientific laws relate, so that "the field of science is much more consciousness than an external world." The consciousness of others is established by an argument from analogy.

We tend to project our sense impressions and to regard them as existing externally to and independently of ourselves, but this is a mistake. The distinction between external and internal is arbitrary and no more than a practical convenience. It is based on distinguishing between classes of sense impressions, not between sense impressions and something else. We cannot assert the existence of causes of sense impressions, but Pearson wanted to leave open the possibility of such existents. He therefore used the term sensation in an unusual way: Sensation is "that of which the only knowable side is sense-impression." This is intended to express agnosticism about the causation of sense impressions while allowing him to say, "The outer world is for science a world of sensations, and sensation is known to us only as sense-impression."

Some scientific concepts are not of immediate sense impressions; for instance, atom and molecule. There are just two possibilities: Scientists may regard the atom as real and thus capable of being a direct sense impression, or as ideal and thus merely a "mental conception assisting them in formulating laws." In contrast, a metaphysical conception is of what is both real and independent of sense perception.

Pearson concluded that science is not explanatory but merely descriptive. For instance, Isaac Newton's law of gravitation is a description in the simplest possible terms of a wide range of phenomena; that is, of the "routine" of our perceptions. To talk of it as ruling nature is to confuse other senses of "law" with the scientific sense. Causal statements are records of regular sequences in past experience and cannot assert any necessity in them. Using Humean arguments, Pearson held that forces, because they are not discoverable in sense experience, cannot be regarded as causes. "Force" is but a name hiding our ignorance of the explanation of motion. The idea of necessity is appropriate only to relations between conceptions, not to relations between perceptions. Prediction and knowledge are possible only because we find repetition in our sense impressions. Even so, our knowledge is only probable and should, strictly speaking, be called "belief."

The whole of science involves the distinction between the perceptual and the conceptual. Scientific concepts generally are ideal limits of concepts originating in perception. This is especially obvious in the mathematical treatment of the world. Empirical space and time are "modes of perception." Space is "a mental expression for the fact that the perceptive faculty has separated coexisting sense impressions into groups of associated impressions"; time indicates "the progression of perceptions at a position in space." Neither space nor time is infinite or infinitely divisible, since each must be limited by our powers of perception and discrimination. Conceptual space and time, and the space and time of mathematics, are idealizations of their empirical counterparts and do not suffer from their limitations.

The aim of science is to construct conceptual models of the universe, devices to assist us in describing the correlation and sequence of phenomena. The failure to recognize this has led scientists to accept definitions of force, mass, atom, and—in the biological sciences—life that are riddled with metaphysical obscurities. Much of Pearson's philosophical writing consists in the empiricist elucidation of these fundamental concepts, in an attempt to remove these obscurities.

Bibliography

Pearson's main philosophical work is The Grammar of Science (London, 1892). The second edition (1900) contained two new chapters. The third (1911) contained only the first eight chapters (physical sciences) of the first two editions but had a new chapter on causation and a new final chapter on modern physical ideas, written largely by E. Cunningham. The Everyman edition (London, 1937) contains a more detailed account of the various editions.

Other works by Pearson are The Ethic of Freethought, a Selection of Essays and Lectures (London: Unwin, 1888; and London: A. and C. Black, 1901); The Chances of Death and Other Studies in Evolution (London: Arnold, 1897), a volume of essays and lectures; National Life from the Standpoint of Science (London: A. and C. Black, 1901); and The Life, Letters and Labours of Francis Galton, 3 vols. (Cambridge, U.K.: Cambridge University Press, 1914–1930).

Pearson edited and completed Isaac Todhunter, A History of the Theory of Elasticity and of the Strength of Materials from Galilei to the Present Time, 2 vols. Cambridge, U.K.: Cambridge University Press, 1886–1893), and W. K. Clifford, Common Sense of the Exact Sciences (New York: Appleton, 1885), for which he wrote the chapter "Position" and much of "Quantity" and "Motion."

Works on Pearson include V. I. Lenin, Materialism and Empirio-Criticism, translated by A. Finchberg (Moscow, 1937); G. M. Morant, A Bibliography of the Statistical and Other Writings of Karl Pearson (London: Biometrika Office, University College, 1939); E. S. Pearson, "Karl Pearson, an Appreciation of Some Aspects of His Life and Work," in Biometrika 27 (1936): 193–257, and 29 (1937): 161–248; C. S. Peirce, Collected Papers (Cambridge, MA: Harvard University Press, 1931–1958), passim, but especially Vol. VIII, which contains a long review of The Grammar of Science ; and G. U. Yule and L. N. G. Filon, "Karl Pearson," in Obituary Notices of Fellows of the Royal Society, Vol. II (London, 1936–1938), pp. 73–110.

For reviews of The Grammar of Science, see those by C. G. K. (probably C. G. Knott) in Nature 46 (1892): 97–99, with replies by Pearson on pp. 199 and 247; by F. A. D. (of 2nd ed.) in Nature 62 (1900): 49–50; by E. A. Singer Jr. (of 2nd ed.) in Philosophical Review 9 (1900): 448–450; and an unsigned review in Mind, n.s., 1 (1892): 429–430.