Originally published in Intellectus
15 (Jul-Sep 1990), pp. 1-3.
Intellectus is the official bulletin of the
Hong Kong Institute of Economic Science (IES).
(HTML Version: 29th January 1997)
Sir Karl was turning 88 when we visited him, and despite some hearing difficulties, he impressed us as a perfectly healthy old gentleman. And while many people at his age would be wearing spectacles and walking with canes, Sir Karl used none. His voice was soft, and his German accent reminded us of his Austrian origin. Also his mind was still very sharp, notwithstanding the five strokes which he had previously suffered. During the five and a half hours which he shared with us (with his former research assistant David Miller joining on 26th July), this great man led us into his world of philosophy, micro-biology, quantum physics, classical music, and politics. He was at home in all these disciplines, and he strongly impressed us with his erudition and, more important still, his unassuming manner. It was one of the most memorable events for both of us. Here, I shall write on Sir Karl's philosophy of biology in general, and his most recent biochemical researches in particular.
For people who know Sir Karl as the author of such books as The Logic of Scientific Discovery, Conjectures and Refutations, and The Open Society and Its Enemies, he is usually recognised as a philosopher of physical science and a humanitarian thinker. It must be noted, however, that his interest in biology is long-standing. According to the late William W. Bartley III,[1] Sir Karl's public discussion of biology can be dated "quite exactly to the afternoon of Tuesday, November 15, 1960," which was already thirty years ago. On that day, Bartley told us, "the members of Popper's seminar had assembled as usual around the long table in the old seminar room on the fourth floor of the Old Building of the London School of Economics. When Popper appeared, he announced that he would abandon the usual format and would read a new paper of his own. The new paper, which spoke of `three worlds', of biology ... took the members of the seminar off guard ... No member of the seminar, perhaps not even Popper, could have predicted that they had just heard the first note in a new development in his thought."
Popper's discussion of biology and evolution theory dominates his later works, such as Objective Knowledge (1972), Unended Quest (1976), and The Self and Its Brain (1977). Back in the 1930's, when he wrote what later became translated as The Logic of Scientific Discovery, the central problem of epistemology, to him, "has always been and still is the problem of the growth of knowledge."[2] Later in the same work, he wrote that the "main problem in philosophy is the critical analysis of the appeal to the authority of experience."[3] Thirty years later, in Conjectures and Refutations, he described the solution to the problem of demarcation between science and non-science as "the key to most of the fundamental problems of the philosophy of science."[4]
In the years since then, Popper has developed his theory of the three worlds and of biology, and has thereby generalised and unified his philosophy of science. We may say that in the years prior to 1960, the development of Popper's philosophy could have been introduced in an incremental way: his new foundations of logical theory, his work in indeterminism in the natural sciences, his axiomatization of probability theory--all of these could have been presented as elaborations of his early position on induction and the problem of demarcation. The new approach from the standpoint of biology, however, is not merely incremental: it unifies his whole philosophy.
The way in which Popper's philosophy of biology contributes to the integration of his thought can be seen in his new expression of the main problem of epistemology, which he formulated in his "Replies to My Critics" of the Schilpp volume The Philosophy of Karl Popper: "The main task of the theory of knowledge is to understand it as continuous with animal knowledge; and to understand also its discontinuity--if any--from animal knowledge."[5] And in his latest book, A World of Propensities, his idea is even more concisely put: "The origin and the evolution of knowledge may be said to coincide with the origin and the evolution of life, and to be closely linked with the origin and evolution of our planet earth. Evolution theory links knowledge, and with it ourselves, with the cosmos; and so the problem of knowledge becomes a problem of cosmology."[6]
Just as for the earlier Popper, the philosopher compared the content of competing theories and assessed their verisimilitude, so for the more recent Popper, the philosopher examines the whole realm of cognitive structures found in the animal kingdom, and compares the "fit" between the organic system and its environment. Thus, Popper significantly generalises his earlier approach: our experience is theory-impregnated and structure-impregnated.
The direct philosophical outcome of Popper's philosophy of biology is a theory of knowledge commonly known as "evolutionary epistemology," sometimes regarded as the most important development in the theory of knowledge since the 18th century. It results from pursuing the implications of Popper's understanding and analysis of the process by which knowledge, be it human or animal, grows. In this setting, the term "knowledge" alludes to the objective end-products of certain evolutionary processes, ranging from the emergence of organs such as the eye, to the most sophisticated scientific theories which Man has propounded.
In the development of evolutionary epistemology, Popper is joined by the Nobel prize winning ethologist and long-time friend, the late Konrad Lorenz, and the American psychologist Donald Campbell. The biological and physiological support and interpretation come partly from Popper himself, but also from Lorenz, Sir John Eccles, Sir Peter Medawar (d. 1987), Ernst Mayr, and Jacques Monod. At the same time, the psychological support can be traced back to Oswald Külpe and Karl Bühler, and is continued in the work of F. A. von Hayek (see especially his The Sensory Order), as well as by Campbell.
In recent years, Popper, being "too old to work alone," as he told us during our July visit, is collaborating with a German biochemist, Günther Wächtershäuser, on the theory of the origin of life. Wächtershäuser, whom Popper calls "a man of great ideas," has been working as an international patent lawyer in Munich since 1970, specializing in chemical and biological inventions, and has published numerous articles in organic chemistry, genetic engineering, and patent law. In 1988, he published a paper which challenged the orthodox theory of the origin of life, usually known as the "soup theory." Entitled "Pyrite Formation, the First Energy Source of Life: a Hypothesis," Wächtershäuser's paper expounds an alternative theory which is also endorsed by Popper.
According to the "soup theory," when the solar system
evolved and the Earth had sufficiently cooled down, the
macro-molecules present in the concoction ("soup") of
elementary chemical molecules started to develop,
organise, and later joined up to form the first
organism. There are, however, at least two strong
reasons against this theory. The first is that the
soup theory demands a low temperature for the soup in
which the macro-molecules developed and joined up,
since if the temperature was not low enough, these
macro-molecules would have quickly decomposed. But
what we know of the Earth in those early days indicates
that no such cool places existed. As Popper writes in
A World of Propensities, the surface of the
earth, and even more the seas, "were much hotter than
today; and even today a watering place supercooled
below 
would not easily be available, except
perhaps near the North Pole or within a refrigerating
plant."[7]
A second reason against the soup theory is that it is extremely unlikely for the macro-molecules in the soup to have joined up and organised themselves into a living organism. The improbability is in fact so great that one would have to assume a very long time-span in order to make the event in question a little bit less improbable--a time-span far larger than the calculated time for which our universe has existed (about 15 billion years). Again, in the words of Popper, "as geologists found, the time-span between the formation of (boiling hot) liquid water and the origin of life is surprisingly short, far too short to allow for an event of such extreme improbability to happen--even if the high temperature were acceptable to the soup theorists."[8]
On the other hand, the alternative theory as advocated by Wächtershäuser and Popper is not beset by difficulties mentioned above. It assumes only the existence of such simple inorganic micro-molecules as those of water, iron, carbon dioxide, and hydrosulphide, and no organic macro-molecules are assumed to be present before the first metabolic cycles began and, with them, the chemical self-organising of life. "The new theory," writes Popper, "shows in detail how organic molecules ... may evolve in time, perhaps deep down in the sea, bound to the surface of pyrite crystals, rather than in a solution. The anaerobic formation of the pyrite crystal creates the free chemical energy needed for the chemical processes ... that constitute the earliest form of pre-cellular life."[9]
The main success of Popper and Wächtershäuser's new theory is that it can explain a lot of biological facts which were never satisfactorily explained, or simply not explained, before. Besides, it also accounts for many biological pathways and is, for this reason, readily testable. (A pathway indicates the routes by which a complicated chemical molecule evolves into a still more complicated chemical molecule.) At our meeting with him on 23rd July, Sir Karl spoke at length on biological pathways and even showed us a large pathway map which bore the title "Biochemical Pathways: Biochemica Diagnostica Theraupetica." In his opinion, a theory on the origin of life must successfully explain biological pathways at the same time.
I have mentioned, and even quoted from, Popper's latest work, A World of Propensities. This is his first book since 1983, and is "dedicated to the memory of my dear wife, Hennie." Popper is notorious in keeping his work from being published on time, always having to correct mistakes and rewriting whole sections when the manuscripts are already in galley proof. Thus, his Postscript to The Logic of Scientific Discovery, written in 1955 and 1956, did not see light until 1982 and 1983, when Bartley resurrected it from oblivion. Again, a collection of essays under the title Philosophy and Physics, first announced in 1974, is still unpublished. When I wrote to him two years ago and inquired on its availability, Sir Karl wrote back in words which betrayed a sense of helplessness: "Philosophy and Physics has not been published, and I don't see any hope of publishing it soon. Publication is a very difficult thing for someone of my age."[10] And according to his friend Bryan Magee, "There remains a wealth of unpublished material. More decades will probably pass before all of it has come out."[11]
For those of us who are attracted to Sir Karl's thoughts, then, his philosophy will still be a developing one for many decades to come. And in the meantime, let us hope that A World of Propensities shall be available in Hong Kong soon. It will be an essential source for us to learn more about the most recent development of his philosophy of biology.
[1] W. W. Bartley III, "The Philosophy of Karl Popper: Part I: Biology and Evolutionary Epistemology," Philosophia (1976), pp. 463-494; quotation on p. 465.
[2] K. Popper, The Logic of Scientific Discovery (1959), p. 15.
[3] Ibid., p. 51.
[4] K. Popper, Conjectures and Refutations (1963), p. 42.
[5] K. Popper, "Replies to My Critics," in P. A. Schilpp, ed., The Philosophy of Karl Popper (1974), p. 1061
[6] K. Popper, A World of Propensities (1990), p. 39.
[7] Ibid., p. 40.
[8] Ibid., pp. 40-1.
[9] Ibid., p. 41.
[10] Private communication, 14th December 1988.
[11] B. Magee, Popper (1973), p. 109.
