The first edition of Darwin’s Origin of Species was published in 1859. In a reply to a letter from John Lubbock, thanking Darwin for an advance copy of his book, Darwin made a remarkable comment about William Paley’s book Natural Theology, which had been published half a century before. Darwin wrote: T do not think I hardly ever admired a book more than Paley’s “Natural Theology”. I could almost formerly have said it by heart.’ Years later in his autobiography Darwin wrote of Paley that ‘The careful study of [his] works ... was the only part of the academical course [in Cambridge] which ... was of the least use to me in the education of my mind.’¹

I have started with these quotations because the problem posed by Paley became one of Darwin’s most important problems. It was the problem of design.

The famous argument from design for the existence of God was at the centre of Paley’s theism. If you find a watch, Paley argued, you will hardly doubt that it was designed by a watchmaker. So if you consider a higher organism, with *ts intricate and purposeful organs such as the eyes, then, Paley argued, you are bound to conclude that it must have been designed by an intelligent creator. This is Paley’s argument from design. Prior to Darwin, the theory of special creation - the theory that each species was designed by the Creator - had been widely accepted, not only in the University of Cambridge, but also elsewhere, by many of the best scientists. There were of course alternative theories in existence, such as Lamarck’s; and Hume had earlier attacked, somewhat feebly, the argument from design; but Paley’s theory was in those days the one most seriously entertained by serious scientists.

It is almost unbelievable how much the atmosphere changed as a consequence of the publication, in 1859, of the Origin of Species. The place of an argument that really had no status whatever in science has been taken by an immense number of the most impressive and well-tested scientific results. Our whole outlook, our picture of the universe, has changed, as never before.

Although Darwin destroyed Paley’s argument from design by showing that what appeared to Paley as purposeful design could as well be explained as the result of chance and of natural selection, he was most modest and undogmatic in his claims. He had a correspondence about divine design with Asa Gray of Harvard,

Design. I am conscious that I am in an utterly hopeless muddle. I cannot think that the world, as we see it, is the result of chance; and yet I cannot look at each separate thing as the result of Design.’ And a year later Darwin wrote to Gray: ‘With respect to Design, I feel more inclined to show a white flag than to fire.... [a] shot. ... You say that you are in a haze; I am in thick mud;... yet I cannot keep out of the question.’²

To me it seems that the question may not be within the reach of science. And yet I do think that science has taught us a lot about the evolving universe that bears in an interesting way on Paley’s and Darwin’s problem of creative design.

I think that science suggests to us (tentatively of course) a picture of a universe that is inventive³ or even creative; of a universe in which new things emerge, on new levels.

There is, on the first level, the theory of the emergence of heavy atomic nuclei in the centre of big stars, and, on a higher level, the evidence for the e mergence somewhere in space of organic molecules.

On the next level, there is the emergence of life. Even if the origin of life should one day become reproducible in the laboratory, life creates something that is utterly new in the universe: the peculiar activity of organisms; especially the often purposeful actions of animals; and animal problem solving. All organisms are constant problem solvers; even though they are not conscious of most of the problems they are trying to solve.

On the next level, the great step is the emergence of conscious states. With the distinction between conscious states and uncon-scious states, again something utterly new and of the greatest importance enters the universe. It is a new world: the world of conscious experience.

On the next level, this is followed by the emergence of the products of the human mind, such as the works of art; and also the works of science; especially scientific theories.

I think that scientists, however sceptical, are bound to admit that the universe, or nature, or whatever we may call it, is creative. For it has produced creative men: it has produced Shakespeare and Michelangelo and Mozart, and thus indirectly their works. It has produced Darwin, and so created the theory of natural selection. Natural selection has destroyed the proof for the miraculous specific intervention of the Creator. But it has left us with the marvel of the creativeness of the universe, of life, and of the human mind. Although science has nothing to say about a personal creator, the fact of the emergence of novelty, and of creativity, can hardly be denied. I think that Darwin himself, who could not ‘keep out of the question', would have agreed that, though natural selection was an idea which opened up a new world for science, it did not remove, from the picture of the universe that science paints, the marvel of creativity; nor did it remove the marvel of freedom: the freedom to create; and the freedom of choosing our own ends and our own purposes.

When speaking here of Darwinism, I shall speak always of today's theory - that is Darwin's own theory of natural selection supported by the Mendelian theory of heredity, by the theory of the mutation and recombination of genes in a gene pool, and by the decoded genetic code. This is an immensely impressive and powerful theory. The claim that it completely explains evolution is of course a bold claim, and very far from being established. All scientific theories are conjectures, even those that have successfully passed many severe and varied tests. The Mendelian underpinning of modem Darwinism has been well tested, and so has the theory of evolution which says that all terrestrial life has evolved from a few primitive unicellular organisms, possibly even from one single organism.

However, Darwin’s own most important contribution to the theory of evolution, his theory of natural selection, is difficult to test. There are some tests, even some experimental tests; and in some cases, such as the famous phenomenon known as 'industrial melanism’, we can observe natural selection happening under our very eyes, as it were. Nevertheless, really severe tests of the theory of natural selection are hard to come by, much more so than tests of otherwise comparable theories in physics or chemistry.

The fact that the theory of natural selection is difficult to test has led some people, anti-Darwinists and even some great Darwinists, to claim that it is a tautology. A tautology like ‘All tables are tables’ is not, of course, testable; nor has it any explanatory power. It is therefore most surprising to hear that some of the greatest contemporary Darwinists themselves formulate the theory in such a way that it amounts to the tautology that those organisms that leave most offspring leave most offspring. C.H. Waddington says somewhere (and he defends this view in other places) that ‘Natural selection ... turns out ... to be a tautology’.⁴ However, he attributes at the same place to the theory an ‘enormous power. ... of explanation’. Since the explanatory power of a tautology is obviously zero, something must be wrong here.

Yet similar passages can be found in the works of such great Darwinists as Ronald Fisher, J.B.S. Haldane, and George Gaylord Simpson; and others.

I mention this problem because I too belong among the culprits. Influenced by what these authorities say, I have in the past described the theory as ‘almost tautological’, and I have tried to explain how the theory of natural selection could be untestable (as is a tautology) and yet of great scientific interest. My solution was that the doctrine of natural selection is a most successful metaphysical research programme. It raises detailed problems in many fields, and it tells us what we would expect of an acceptable solution of these problems.⁵

I still believe that natural selection works in this way as a research programme. Nevertheless, I have changed my mind about the testability and the logical status of the theory of natural

selection; and I am glad to have an opportunity to make a recantation. My recantation may, I hope, contribute a little to the understanding of the status of natural selection.

What is important is to realize the explanatory task of natural selection; and especially to realize what can be explained without the theory⁷ of natural selection.

We may start from the remark that, for sufficiently small and reproductively isolated populations, the Mendelian theory of genes and the theory of mutation and recombination together suffice to predict, without natural selection, what has been called 'genetic drift’. If you isolate a small number of individuals from the main population and prevent them from interbreeding with the main population, then, after a time, the distribution of genes in the gene pool of the new population will differ somewhat from that of the original population. This will happen even if selection pressures are completely absent.

Moritz Wagner, a contemporary of Darwin, and of course a pre-Mendelian, was aware of this situation. He therefore introduced a theory of evolution by genetic drift, made possible by reproductive isolation through geographical separation.

In order to understand the task of natural selection, it is good to remember Darwin’s reply to Wagner.⁶ Darwin’s main reply to Wagner was: if you have no natural selection, you cannot explain the evolution of the apparently designed organs, like the eye. Or in other words, without natural selection, you cannot solve Paley’s problem.

refuted. For not all organs serve a useful purpose: as Darwin himself points out, there are organs like the tail of the peacock, and behavioural programmes like the peacock’s display of his tail, which cannot be explained by their utility, and therefore not by

In its most daring and sweeping form, the theory of natural selection would assert that all organisms, and especially all those highly complex organs whose existence might be interpreted as evidence of design and, in addition, all forms of animal behaviour, have evolved as the result of natural selection; that is, as the result of chancelike inheritable variations, of which the useless ones are weeded out, so that only the useful ones remain. If formulated in this sweeping way, the theory is not only refutable, but actually

natural selection. Darwin explained them by the preference of the other sex, that is, by sexual selection. Of course one can get round this refutation by some verbal manoeuvre: one can get round any refutation of any theory. But then one does get near to rendering the theory tautological. It seems far preferable to admit that not everything that evolves is useful, though it is astonishing how many things are; and that in conjecturing what is the use of an organ or a behavioural programme, we conjecture a possible explanation by natural selection: of why it evolved in the way it has, and perhaps even of how it evolved. In other words, it seems to me that like so many theories in biology, evolution by natural selection is not strictly universal, though it seems to hold for a vast number of important cases.

According .to Darwin’s theory, sufficiently invariant selection pressures may turn the otherwise random genetic drift into a drift that has the appearance of being purposefully directed. In this way, the selection pressures, if there are any, will leave their imprint upon the genetic material. (It may be mentioned, however, that there are selection pressures that can operate successfully over very short periods: one severe epidemic may leave alive only those who are genetically immune.)

I may now briefly sum up what I have said so far about Darwin’s theory of natural selection.

The theory of natural selection may be so formulated that it is far from tautological. In this case it is not only testable, but it turns out to be not strictly universally true. There seem to be exceptions, as with so many biological theories; and considering the random character of the variations on which natural selection operates, the occurrence of exceptions is not surprising. Thus not all phenomena of evolution are explained by natural selection alone. Yet in every particular case it is a challenging research programme to show how far natural selection can possibly be held responsible for the evolution of a particular organ or behavioural programme.

It is of considerable interest that the idea of natural selection can be generalized. In this connection it is helpful to discuss the relation between selection and instruction. While Darwin’s theory is selectionist, the theistic theory of Paley is instructionist. It is the Creator who, by His design, moulds matter, and instructs it which shape to take. Thus Darwin’s selectionist theory can be regarded as a theory that explains by selection something that looks like instruction. Certain invariant features of the environment leave their imprint on the genetic material as if they had moulded it; while in fact, they selected it.

Many years ago I visited Bertrand Russell in his rooms at Trinity College and he showed me a manuscript of his in which there was not a single correction for many pages. With the help of his pen, he had instructed the paper. This is very different indeed from what I do. My own manuscripts are full of corrections - so full that it is easy to see that I am working by something like trial and error; by more or less random fluctuations from which I select what appears to me fitting. We may pose the question whether Russell did not do something similar, though only in his mind, and perhaps not even consciously, and at any rate very rapidly. For indeed, what seems to be instruction is frequently based upon a roundabout mechanism of selection, as illustrated by Darwin’s answer to the problem posed by Paley.

I suggest that we might try out the conjecture that something like this happens in many cases. We may indeed conjecture that Bertrand Russell produced almost as many trial formulations as I do, but that his mind worked more quickly than mine in trying them out and rejecting the non-fitting verbal candidates. Einstein somewhere says that he produced and rejected an immense number of hypotheses before hitting on (and first rejecting) the equations of general relativity. Clearly, the method of production and selection is one that operates with negative feedback. [See also pp.83-6 above.]

One of the important points about this roundabout method of selection is that it throws light on the problem of downward causation to which Donald Campbell and Roger Sperry have called attention.⁷

We may speak of downward causation whenever a higher structure operates causally upon its substructure. The difficulty of understanding downward causation is this. We think we can understand how the substructures of a system co-operate to affect the whole system; that is to say, we think that we understand upward causation. But the opposite is very difficult to envisage. For the set of substructures, it seems, interacts causally in any case, and there is no room, no opening, for an action from above to interfere. It is this that leads to the heuristic demand that we explain everything in terms of molecular or other elementary particles (a demand that is sometimes called ‘reductionism’).

I suggest that downward causation can sometimes at least be explained as selection operating on the randomly fluctuating elementary particles. The randomness of the movements of the elementary particles - often called ‘molecular chaos’ - provides, as it were, the opening for the higher-level structure to interfere. A random movement is accepted when it fits into the higher level structure; otherwise it is rejected.

I think that these considerations tell us a lot about natural selection. While Darwin still worried that he could not explain variation, and while he felt uneasy about being forced to look at it as chancelike, we can now see that the chancelike character of mutations, which may go back to quantum indeterminacy, explains how the abstract invariances of the environment, the somewhat abstract selection pressures, can, by selection, have a downward effect on the concrete living organism - an effect that may be amplified by a long sequence of generations linked by heredity.

The selection of a kind of behaviour out of a randomly offered repertoire may be an act of choice, even an act of free will. I am an indeterminist; and in discussing indeterminism I have often regretfully pointed out [for example, in selection 20, section vn, below] that quantum indeterminacy does not seem to help us; for the amplification of something like, say, radioactive disintegration processes would not lead to human action or even animal action, but only to random movements. I have changed my mind on this issue.⁸ A choice process may be a selection process, and the selection may be from some repertoire of random events, without being random in its turn. This seems to me to offer a promising solution to one of our most vexing problems, and one by downward causation.

The central purpose of my lecture is to try to put simply and forcefully before you the ancient problems referred to in my title. But first I must say something about clouds and clocks.

My clouds are intended to represent physical systems which, like gases, are highly irregular, disorderly, and more or less unpredictable. I shall assume that we have before us a schema or arrangement in which a very disturbed or disorderly cloud is placed on the left. At the other extreme of our arrangement, on its right, we may place a very reliable pendulum clock, a precision clock, intended to represent physical systems which are regular, orderly, and highly predictable in their behaviour.

According to what I may call the commonsense view of things, some natural phenomena, such as the weather, or the coming and going of clouds, are hard to predict: we speak of the ‘vagaries of the weather’. On the other hand, we speak of‘clockwork precision’ if we wish to describe a highly regular and predictable phenomenon.

There are lots of things, natural processes and natural phenomena, which we may place between these two extremes - the clouds on the left, and the clocks on the right. The changing seasons are somewhat unreliable clocks, and may therefore be put somewhere towards the right, though not too far. I suppose we shall easily agree to put animals not too far from the clouds on the left, and plants somewhat nearer to the clocks. Among the animals, a young puppy will have to be placed further to the left than an old dog. Motor cars, too, will find their place somewhere in our arrangement, according to their reliability: a Cadillac, I suppose, is pretty far over to the right, and even more so a Rolls-Royce, which will be quite close to the best of the clocks. Perhaps furthest to the right should be placed the solar system.¹

As a typical and interesting example of a cloud I shall make some use here of a cloud or cluster of small flies or gnats. Like the individual molecules in a gas, the individual gnats which together form a cluster of gnats move in an astonishingly irregular way. It is almost impossible to follow the flight of any one individual gnat, even though each of them may be quite big enough to be clearly visible.

Apart from the fact that the velocities of the gnats do not show a very wide spread, the gnats present us with an excellent picture of the irregular movement of molecules in a gas cloud, or of the minute drops of water in a storm cloud. There are, of course, differences. The cluster does not dissolve or diffuse, but it keeps together fairly well. This is surprising, considering the disorderly character of the movement of the various gnats; but it has its analogue in a sufficiently big gas cloud (such as our atmosphere, or the sun) which is kept together by gravitational forces. In the case of the gnats, their keeping together can be easily explained if we assume that, although they fly quite irregularly in all directions, those that find that they are getting away from the crowd turn back towards that part which is densest.

This assumption explains how the cluster keeps together even though it has no leader, and no structure - only a random statistical distribution resulting from the fact that each gnat does exactly what he likes, in a lawless or random manner, together with the fact that he does not like to stray too far from his comrades.

I think that a philosophical gnat might claim that the gnat society is a great society or at least a good society, since it is the most egalitarian, free, and democratic society imaginable.

However, as the author of a book on The Open Society, I would deny that the gnat society is an open society. For I take it to be one of the characteristics of an open society that it cherishes, apart from a democratic form of government, the freedom of association, and that it protects and even encourages the formation of free subsocieties, each holding different opinions and beliefs. But every reasonable gnat would have to admit that in his society this kind of pluralism is lacking.

I do not intend, however, to discuss today any of the social or political issues connected with the problem of freedom; and I intend to use the cluster of gnats not as an example of a social system, but rather as my main illustration of a cloudlike physical system, as an example or paradigm of a highly irregular or disordered cloud.

Like many physical, biological, and social systems, the cluster of gnats may be described as a ‘whole’. Our conjecture that it is kept together by a kind of attraction which its densest part exerts on individual gnats straying too far from the crowd shows that there is even a kind of action or control which this ‘whole’ exerts upon its elements or parts. [See the remarks on downward causation on pp.245f. above.] Nevertheless, this ‘whole’ can be used to dispel the widespread ‘holistic’ belief that a ‘whole’ is always more than a mere sum of its parts. I do not deny that it may sometimes be so.² Yet the cluster of gnats is an example of a whole that is indeed nothing but the sum of its parts - and in a very precise sense; for not only is it completely described by describing the movements of all the individual gnats, but the movement of the whole is, in this case, precisely the (vectorial) sum of the movements of its constituent members, divided by the number of the members.

An example (in many ways similar) of a biological system or ‘whole’ which exerts some control over the highly irregular movements of its parts would be a picnicking family - parents with a few children and a dog - roaming the woods for hours, but never straying far from the family car (which acts as a centre of attraction, as it were). This system may be said to be even more cloudy - that is, less regular in the movement of its parts - than our cloud of gnats.

I hope you will now have before you an idea of my two prototypes or paradigms, the clouds on the left and the clocks on the right, and of the way in which we can arrange many kinds of things, and many kinds of systems, between them. I am sure you have caught some vague, general idea of the arrangement, and you need not worry if your idea is still a bit foggy, or cloudy.

n Physical Determinism

The arrangement I have described is, it seems, quite acceptable to common sense; and more recently, in our own time, it has become acceptable even to physical science. It was not so, however, during the preceding 250 years: the Newtonian revolution, one of the greatest revolutions in history, led to the rejection of the commonsense arrangement which I have tried to present to you. For one of the things which almost everybody³ thought had been established by the Newtonian revolution was the following staggering proposition:

This proposition, ‘All clouds are clocks’, may be taken as a brief formulation of the view which I shall call⁴physical determinism’.

The physical determinist who says that all clouds are clocks will also say that our commonsense arrangement, with the clouds on the left and the clocks on the right, is misleading, since everything ought to be placed on the extreme right. He will say that, with all our common sense, we arranged things not according to their nature, but merely according to our ignorance. Our arrangement, he will say, reflects merely the fact that we know in some detail how the parts of a clock work, or how the solar system works, while we do not have any knowledge about the detailed interaction of the particles that form a gas cloud, or an organism. And he will assert that, once we have obtained this knowledge, we shall find that gas clouds or organisms are as clocklike as our solar system.

Newton’s theory did not, of course, tell the physicists that this was so. In fact, it did not treat at all of clouds. It treated especially of planets, whose movements it explained as due to some very simple laws of nature; also of cannon balls, and of the tides. But its immense success in these fields turned the physicists’ heads; and surely not without reason.

Before the time of Newton and his predecessor, Kepler, the movements of the planets had escaped many attempts to explain or even to describe them fully. Clearly, they somehow participated in the unvarying general movement of the rigid system of the fixed stars; yet they deviated from the movement of that system almost like single gnats deviating from the general movement of a cluster of gnats. Thus the planets, not unlike living things, appeared to

be in a position intermediate between clouds and clocks. Yet the success of Kepler’s and even more of Newton’s theory showed that those thinkers had been right who had suspected that the planets were in fact perfect clocks. For their movements turned out to be precisely predictable with the help of Newton’s theory; predictable in all those details which had previously baffled the astronomers by their apparent irregularity.

Newton’s theory was the first really successful scientific theory in human history; and it was tremendously successful. Here was real knowledge; knowledge beyond the wildest dreams of even the boldest minds. Here was a theory which explained precisely not only the movements of all the stars in their courses, but also, just as precisely, the movements of bodies on earth, such as falling apples, or projectiles, or pendulum clocks. And it even explained the tides.

All openminded men - all those who were eager to learn, and who took an interest in the growth of knowledge - were converted to the new theory. Most openminded men, and especially most scientists, thought that in the end it would explain everything, including not only electricity and magnetism, but also clouds, and even living organisms. Thus physical determinism - the doctrine that all clouds are clocks - became the ruling faith among enlightened men; and everybody who did not embrace this new faith was held to be an obscurantist or a reactionary.⁴

m Indeterminism

Among the few dissenters⁵ was Charles Sanders Peirce, the great American mathematician and physicist and, I believe, one of the greatest philosophers of all time. He did not question Newton’s theory; yet as early as 1892 he showed that this theory, even if true, does not give us any valid reason to believe that clouds are perfect clocks. Though in common with all other physicists of his time he believed that the world was a clock that worked according to Newtonian laws, he rejected the belief that this clock, or any other, was perfect, down to the smallest detail. He pointed out that at any rate we could not possibly claim to know, from experience, of anything like a perfect clock, or of anything even faintly approaching that absolute perfection which physical determinism

‘... one who is behind the scenes’ (Peirce speaks here as an experimentalist) ‘... knows that the most refined comparisons [even] of masses [and] lengths,... far surpassing in precision all other [physical] measurements, ... fall behind the accuracy of bank accounts, and that the ... determinations of physical constants ... are about on a par with an upholsterer’s measurements of carpets and curtains____’⁶ From this Peirce concluded

that we were free to conjecture that there was a certain looseness or imperfection in all clocks, and that this allowed an element of chance to enter. Thus Peirce conjectured that the world was not only ruled by the strict Newtonian laws, but that it was also at the same time ruled by laws of chance, or of randomness, or of disorder: by laws of statistical probability. This made the world an interlocking system of clouds and clocks, so that even the best clock would, in its molecular structure, show some degree of cloudiness. So far as I know Peirce was the first post-Newtonian physicist and philosopher who thus dared to adopt the view that to some degree all clocks are clouds:; or in other words, that only clouds exist, though clouds of very different degrees of cloudiness.

Peirce supported this view by pointing out, no doubt correctly, that all physical bodies, even the jewels in a watch, were subject to molecular heat motion,⁷ a motion similar to that of the molecules of a gas, or of the individual gnats in a cluster of gnats.

These views of Peirce’s were received by his contemporaries with little interest. Apparently only one philosopher noticed them; and he attacked them.⁸ Physicists seem to have ignored them; and even today most physicists believe that if we had to accept the classical mechanics of Newton as true, we should be compelled to accept physical determinism, and with it the proposition that all clouds are clocks. It was only with the downfall of classical physics and with the rise of the new quantum theory that physicists were prepared to abandon physical determinism.

Now the tables were turned. Indeterminism, which up to 1927 had been equated with obscurantism, became the ruling fashion; and some great scientists, such as Max Planck, Erwin Schrodinger, and Albert Einstein, who hesitated to abandon determinism, were considered old fogies,⁹ although they had been in the forefront of the development of quantum theory. I myself once heard a brilliant

young physicist describe Einstein, who was then still alive and hard at work, as ‘antediluvian’. The deluge that was supposed to have swept Einstein away was the new quantum theory, which had risen during the years from 1925 to 1927, and to whose advent at most seven people had made contributions comparable to those of Einstein.

iv The Nightmare of the Physical Determinist

Arthur Holly Compton was among the first who welcomed the new quantum theory and Heisenberg’s new physical indeterminism of 1927. In 1931 he became also one of the first to examine the human and, more generally, the biological implications of this new indeterminism.¹⁰ And now it became clear why he had welcomed the new theory so enthusiastically: it solved for him not only problems in physics but also biological and philosophical problems, and among the latter especially problems connected with ethics.

To show this, I shall quote the striking opening passage of Compton’s The Freedom of Man:

The fundamental question of morality, a vital problem in religion, and a subject of active investigation in science: Is man a free agent?

If ... the atoms of our bodies follow physical laws as immutable as the motions of the planets, why try? What difference can it make how great the effort if our actions are already predetermined by mechanical laws ... ?

Compton describes here what I shall call ‘the nightmare of the physical determinist’. A deterministic physical clockwork mechanism is, above all, completely self-contained: in the perfect deterministic physical world there is simply no room for any outside intervention. Everything that happens in such a world is physically predetermined, including all our movements and therefore all our actions. Thus all our thoughts, feelings, and efforts can have no practical influence upon what happens in the physical world: they are, if not mere illusions, at best superfluous byproducts (‘epiphenomena’) of physical events.

In this way, the daydream of the Newtonian physicist who hoped to prove all clouds to be clocks had threatened to turn into a nightmare; and the attempt to ignore this had led to something like an intellectual split personality. Compton, I think, was grateful to the new quantum theory for rescuing him from this difficult intellectual situation. Thus he writes, in The Freedom of Man: ‘The physicist has rarely ... bothered himself with the fact that if ... completely deterministic ... laws ... apply to man’s actions, he is himself an automaton.’ And in The Human Meaning of Science he expresses his relief:

In my own thinking on this vital subject I am thus in a much more satisfied state of mind than I could have been at any earlier stage of science. If the statements of the laws of physics were assumed correct, one would have had to suppose (as did most philosophers) that the feeling of freedom is illusory, or if [free] choice were considered effective, that the statements of the laws of physics were ... unreliable. The dilemma has been an uncomfortable one. ...

Later in the same book Compton sums up the situation crisply in the words: ‘... it is no longer justifiable to use physical law as evidence against human freedom. ’

These quotations from Compton show clearly that before Heisenberg he had been harassed by what I have here called the nightmare of the physical determinist, and that he had tried to escape from this nightmare by adopting something like an intellectual split personality. Or as he himself puts it: ‘We [physicists] have preferred merely to pay no attention to the

I believe that the only form of the problem of determinism which is worth discussing seriously is exactly that problem which worried Compton: the problem which arises from a physical theory which describes the world as a physically complete or a physically closed system.¹² By a physically closed system I mean a set or system of physical entities, such as atoms or elementary particles or physical forces or fields of forces, which interact with each other - and only with each other - in accordance with definite laws of interaction

that do not leave any room for interaction with, or interference by, anything outside that closed set or system of physical entities. It is this ‘closure’ of the system that creates the deterministic nightmare.¹³

v Psychological Determinism

I should like to digress here for a minute in order to contrast the problem of physical determinism, which I consider to be of fundamental importance, with the far from serious problem which many philosophers and psychologists, following Hume, have substituted for it.

Hume interpreted determinism (which he called ‘the doctrine of necessity’, or ‘the doctrine of constant conjunction’) as the doctrine that ‘like causes always produce like effects’ and that ‘like effects necessarily follow from like causes’. Concerning human actions and volitions he held, more particularly, that ‘a spectator can commonly infer our actions from our motives and character; and even where he cannot, he concludes in general, that he might, were he perfectly acquainted with every circumstance of our situation

disposition.

put it thus: our actions, or our volitions, or our tastes, or our preferences, are psychologically ‘caused’ by preceding experiences (‘motives’), and ultimately by our heredity and environment.

But this doctrine which we may call philosophical or psychological determinism is not only a very different affair from physical determinism, but it is also one which a physical determinist who understands the matter at all can hardly take seriously. For the thesis of philosophical determinism, that ‘Like effects have like causes’ or that ‘Every event has a cause’, is so vague that it is perfectly compatible with physical indeterminism.

merely the doctrine that not all events in the physical world are predetermined with absolute precision, in all their infinitesimal details. Apart from this, it is compatible with practically any degree of regularity you like, and it does not, therefore, entail the view that there are ‘events without causes’; simply because the terms ‘event’ and ‘cause’ are vague enough to make the doctrine

that every event has a cause compatible with physical indeterminism. While physical determinism demands complete and infinitely precise physical predetermination and the absence of any exception whatever, physical indeterminism asserts no more than that determinism is false, and that there are at least some exceptions, here or there, to precise predetermination.

Thus even the formula ‘Every observable or measurable physical event has an observable or measurable physical cause’ is still compatible with physical indeterminism, simply because no measurement can be infinitely precise: for the salient point about physical determinism is that, based on Newton’s dynamics, it asserts the existence of a world of absolute mathematical precision. And although in so doing it goes beyond the realm of possible observation (as was seen by Peirce), it nevertheless is testable, in principle, with any desired degree of precision; and it actually withstood surprisingly precise tests.

By contrast, the formula ‘Every event has a cause’ says nothing about precision; and if, more especially, we look at the laws of psychology, then there is not even a suggestion of precision. This holds for a ‘behaviourist’ psychology as much as for an ‘introspective’ or ‘mentalist’ one. In the case of a mentalist psychology this is obvious. But even a behaviourist may at the very best predict that, under given conditions, a rat will take twenty to twenty two seconds to run a maze: he will have no idea how, by specifying more and more precise experimental conditions, he could make predictions which become more and more precise - and, in principle, precise without limit. This is so because behaviourist ‘laws’ are not, like those of Newtonian physics, differential equations, and because every attempt to introduce such differential equations would lead beyond behaviourism into physiology, and thus ultimately into physics; so it would lead us back to the problem of physical determinism.

As noted by Laplace, physical determinism implies that every physical event in the distant future (or in the distant past) is predictable (or retrodictable) with any desired degree of precision, provided we have sufficient knowledge about the present state of the physical world. The thesis of a philosophical (or psychological) determinism of Hume’s type, on the other hand, asserts even in its strongest interpretation no more than that any observable

difference between two events is related by some as yet perhaps unknown law to some difference - an observable difference perhaps - in the preceding state of the world; obviously a very much weaker assertion, and incidentally one which we could

continue to uphold

under conditions which are, in appearance, ‘entirely equal’, should yield different results. This was stated very clearly by Hume himself. ‘Even when these contrary experiments are entirely equal’, he writes, ‘we remove not the notion of causes and necessity, but... conclude, that the [apparent] chance... lies only

This is why a Humean philosophical determinism and, more especially, a psychological determinism, lack the sting of physical determinism. For in Newtonian physics things really looked as if any apparent looseness in a system was in fact merely due to our

any appearance of looseness would disappear. Psychology, on the other hand, never had this character.

Physical determinism, we might say in retrospect, was a daydream of omniscience which seemed to become more real with every advance in physics until it became an apparently inescapable nightmare. But the corresponding daydreams of the psychologists were never more than castles in the air: they were Utopian dreams of attaining equality with physics, its mathematical methods, and its powerful applications; and perhaps even of attaining superiority, by moulding men and societies. (While these totalitarian dreams are not serious from a scientific point of view, they are very dangerous politically [see especially selections 23 and 24

vi Criticism of Physical Determinism

I have called physical determinism a nightmare. It is a nightmare because it asserts that the whole world with everything in it is a huge automaton, and that we are nothing but little cogwheels, or at best sub-automata, within it.

to a complete illusion the idea that in preparing this lecture I have used my brain to create something new. There was no more in it, according to physical determinism, than that certain parts of my body put down black marks on white paper: any physicist with sufficient detailed information could have written my lecture by the simple method of predicting the precise places on which the physical system consisting of my body (including my brain, of course, and my fingers) and my pen would put down those black marks.

Or to use a more impressive example: if physical determinism is right, then a physicist who is completely deaf and who has never heard any music could write all the symphonies and concertos written by Mozart or Beethoven, by the simple method of studying the precise physical states of their bodies and predicting where they would put down black marks on their lined paper. And our deaf physicist could do even more: by studying Mozart’s or Beethoven’s bodies with sufficient care he could write scores which were never actually written by Mozart or Beethoven, but which they would have written had certain external circumstances of their lives been different: if they had eaten lamb, say, instead of chicken, or drunk tea instead of coffee.

All this could be done by our deaf physicist if supplied with a sufficient knowledge of purely physical conditions. There would be no need for him to know anything about the theory of music - though he might be able to predict what answers Mozart or Beethoven would have written down under examination conditions if presented with questions on the theory of counterpoint .

I believe that all this is absurd;¹⁷ and its absurdity becomes even more obvious, I think, when we apply this method of physical prediction to a determinist.

For according to determinism, any theories - such as, say, determinism - are held because of a certain physical structure of the holder (perhaps of his brain). Accordingly we are deceiving ourselves (and are physically so determined as to deceive ourselves) whenever we believe that there are such things as arguments or reasons which make us accept determinism. Or in other words, physical determinism is a theory which, if it is true, is not arguable, since it must explain all our reactions, including what appear to us

as beliefs based on arguments, as due to purely physical conditions. Purely physical conditions, including our physical environment, make us say or accept whatever we say or accept; and a well-trained physicist who does not know any French, and who has never heard of determinism, would be able to predict what a French determinist would say in a French discussion on determinism; and of course also what his indeterminist opponent would say. But this means that if we believe that we have accepted a theory like determinism because we were swayed by the logical force of certain arguments, then we are deceiving ourselves, according to physical determinism; or more precisely, we are in a physical condition which determines us to deceive ourselves.

Hume saw much of this, even though it appears that he did not quite see what it meant for his own arguments; for he confined himself to comparing the determinism of ‘our judgments' with that of ‘our actions’, saying that ‘we have not more liberty in the one than in the other’

Considerations such as these may perhaps be the reason why there are so many philosophers who refuse to take the problem of physical determinism seriously and dismiss it as a ‘bogy’.¹⁹ Yet the doctrine that man is a machine was argued most forcefully and seriously in 1751, long before the theory of evolution became generally accepted, by de La Mettrie; and the theory of evolution gave the problem an even sharper edge, by suggesting that there may be no clear distinction between living matter and dead matter.²⁰ And in spite of the victory of the new quantum theory, and the conversion of so many physicists to indeterminism, de La Met trie’s doctrine that man is a machine has today perhaps more defenders than ever before among physicists, biologists, and philosophers; especially in the form of the thesis that man is a computer.²¹

For if we accept a theory of evolution (such as Darwin’s) then even if we remain sceptical about the theory that life emerged from inorganic matter we can hardly deny that there must have been a time when abstract and non-physical entities, such as reasons and arguments and scientific knowledge, and abstract rules, such as rules for building railways or bulldozers or sputniks or, say, rules of grammar or of counterpoint, did not exist, or at any rate had no effect upon the physical universe. It is difficult to understand

how the physical universe could produce abstract entities such as rules, and then could come under the influence of these rules, so that these rules in their turn could exert very palpable effects upon the physical universe. [See section hi of selection 4 above.]

There is, however, at least one perhaps somewhat evasive but at any rate easy way out of this difficulty. We can simply deny that these abstract entities exist and that they can influence the physical universe. And we can assert that what do exist are our brains, and that these are machines like computers; that the allegedly abstract rules are physical entities, exactly like the concrete physical punch-cards by which we ‘programme’ our computers; and that the existence of anything non-physical is just ‘an illusion’, perhaps, and at any rate unimportant, since everything would go on as it does even if there were no such illusions.

According to this way out, we need not worry about the ‘mental’ status of these illusions. They may be universal properties of all things: the stone which I throw may have the illusion that it jumps, just as I have the illusion that I throw it; and my pen, or my computer, may have the illusion that it works because of its interest in the problems which it thinks that it is solving - and which I think I am solving - while in fact there is nothing of any significance going on except purely physical interactions.

You may see from all this that the problem of physical determinism which worried Compton is indeed a serious problem. It is not just a philosophical puzzle, but it affects at least physicists, biologists, behaviourists, psychologists, and computer engineers.

Admittedly, quite a few philosophers have tried to show (following Hume or Schlick) that it is merely a verbal puzzle, a puzzle about the use of the word ‘freedom’. But these philosophers have hardly seen the difference between the problem of physical determinism and that of philosophical determinism; and either they are determinists like Hume, which explains why for them ‘freedom’ is ‘just a word’, or they have never had that close contact with the physical sciences or with computer engineering which would have impressed upon them that we are faced with more than a merely verbal puzzle.

vn Indeterminism Is Not Enough

Like Compton I am among those who take the problem of physical determinism seriously, and like Compton I do not believe that we are mere computing machines (though I readily admit that we can learn a great deal from computing machines - even about ourselves). Thus, like Compton, I am a physical indeterminist: physical indeterminism, I believe, is a necessary prerequisite for any solution of our problem. We have to be indeterminists; yet I shall try to show that indeterminism is not enough.

With this statement, indeterminism is not enough, I have arrived, not merely at a new point, but at the very heart of my problem.

If determinism is true, then the whole world is a perfectly running flawless clock, including all clouds, all organisms, all animals, and all men. If, on the other hand, Peirce’s or Heisenberg’s or some other form of indeterminism is true, then sheer chance plays a major role in our physical world. But is chance really more satisfactory than determinism?

The question is well known. Determinists like Schlick have put it in this way: ‘... freedom of action, responsibility, and mental sanity, cannot reach beyond the realm of causality: they stop where chance begins ... a higher degree of randomness ... [simply means] a higher degree of irresponsibility.’²²

I may perhaps put this idea of Schlick’s in terms of an example I have used before: to say that the black marks made on white paper which I produced in preparation for this lecture were just the result of chance is hardly more satisfactory than to say that they were physically predetermined. In fact, it is even less satisfactory. For some people may perhaps be quite ready to believe that the text of my lecture can be in principle completely explained by my physical heredity, and my physical environment, including my upbringing, the books I have been reading, and the talks I have listened to; but hardly anybody will beheve that what I am reading to you is the result of nothing but chance - just a random sample of English words, or perhaps of letters, put together without any purpose, deliberation, plan, or intention.

The idea that the only alternative to determinism is just sheer chance was taken over by Schlick, together with many of his views

on the subject, from Hume, who asserted that ‘the removal’ of what he called ‘physical necessity’ must always result in ‘the same thing with chance. As objects must either be conjoin’d or not,... ’tis impossible to admit of any medium betwixt chance and an absolute necessity.’²³

I shall in a moment argue against this important doctrine according to which the only alternative to determinism is sheer chance. Yet I must admit that the doctrine seems to hold good for the quantum-theoretical models which have been designed to explain, or at least to illustrate, the possibility of human freedom. This seems to be the reason why these models are so very unsatisfactory.

Compton himself designed such a model, though he did not particularly like it. It uses quantum indeterminacy, and the unpredictability of a quantum jump, as a model of a human decision of great moment. It consists of an amplifier which amplifies the effect of a single quantum jump in such a way that it may either cause an explosion or destroy the relay necessary for bringing the explosion about. In this way one single quantum jump may be equivalent to a major decision. But in my opinion the model has no similarity to any rational decision. It is, rather, a model of a kind of decision-making where people who cannot make up their minds say: ‘Let us toss a penny.’ In fact, the whole apparatus for amplifying a quantum jump seems rather unnecessary: tossing a penny, and deciding on the result of the toss whether or not to pull a trigger, would do just as well. And there are of course computers with built-in penny-tossing devices for producing random results, where such are needed.

It may perhaps be said that some of our decisions are like penny tosses: they are snap decisions, taken without deliberation, since we often do not have enough time to deliberate. A driver or a pilot has sometimes to take a snap decision like this; and if he is well trained, or just lucky, the result may be satisfactory; otherwise not.

I admit that the quantum-jump model may be a model for such snap decisions; and I even admit that it is conceivable that something like the amplification of a quantum jump may actually happen in our brains if we make a snap decision. But are snap

decisions really so very interesting? Are they characteristic of human behaviour - of rational human behaviour?

I do not think so; and I do not think that we shall get much further with quantum jumps. They are just the kind of examples which seem to lend support to the thesis of Hume and Schlick that perfect chance is the only alternative to perfect determinism. What we need for understanding rational human behaviour - and indeed, animal behaviour - is something intermediate in character between perfect chance and perfect determinism - something intermediate between perfect clouds and perfect clocks.

Hume’s and Schlick’s ontological thesis that there cannot exist anything intermediate between chance and determinism seems to me not only highly dogmatic (not to say doctrinaire) but clearly absurd; and it is understandable only on the assumption that they believed in a complete determinism in which chance has no status except as a symptom of our ignorance. (But even then it seems to me absurd, for there is, clearly, something like partial knowledge, or partial ignorance.) For we know that even highly reliable clocks are not really perfect, and Schlick (if not Hume) must have known that this is largely due to factors such as friction - that is to say, to statistical or chance effects. And we also know that our clouds are not perfectly chancelike, since we can often predict the weather quite successfully, at least for short periods.

vra Compton’s Problem

Thus we shall have to return to our old arrangement with clouds on the left and clocks on the right and animals and men somewhere in between.

with presentday physics), even then we have at best only made room for our main question.

For obviously what we want is to understand how such non-physical things as purposes, deliberations, plans, decisions, theories, intentions, and values, can play a part in bringing about physical changes in the physical world. That they do this seems to be obvious, pace Hume and Laplace and Schlick. It is clearly untrue that all those tremendous physical changes brought about

hourly by our pens, or pencils, or bulldozers, can be explained in purely physical terms, either by a deterministic physical theory, or (by a stochastic theory) as due to chance.

Compton was well aware of this problem, as the following charming passage from his Terry Lectures shows:²⁴

It was some time ago when I wrote to the secretary of Yale University agreeing to give a lecture on November 10 at 5 p.m. He had such faith in me that it was announced publicly that I should be there, and the audience had such confidence in his word that they came to the hall at the specified time. But consider the great physical improbability that their confidence was justified. In the meanwhile my work called me to the Rocky Mountains and across the ocean to sunny Italy. A phototropic organism [such as I happen to be, would not easily] ... tear himself away from there to go to chilly New Haven. The possibilities of my being elsewhere at this moment were infinite in number. Considered as a physical event, the probability of meeting my engagement would have been fantastically small. Why then was the audience’s belief justified?... They knew my purpose, and it was my purpose [which] determined that I should be there.

Compton shows here very beautifully that mere physical indeterminism is not enough. We have to be indeterminists, to be sure; but we must also try to understand how men, and perhaps animals, can be ‘influenced’ or ‘controlled’ by such things as aims, or purposes, or rules, or agreements.

i World 3 and the Mind-Body Problem

It is one of the central conjectures of The Self and Its Brain that the consideration of world 3 [see selection 4 above] can throw some new light on the mind-body problem. I will briefly state three arguments.

(1) World 3 objects are abstract (even more abstract than physical forces), but none the less real; for they are powerful tools for changing world 1. (I do not wish to imply that this is the only reason for calling them real, or that they are nothing but tools.)

(2) World 3 objects have an effect on world 1 only through human intervention, the intervention of their makers; more especially, through being grasped, which is a world 2 process, a mental process, or more precisely, a process in which world 2 and world 3 interact.

(3) We therefore have to admit that both world 3 objects and the processes of world 2 are real - even though we may not like this admission, out of deference, say, to the great tradition of materialism.

I think that this is an acceptable argument - though, of course, it is open to someone to deny any one of its assumptions. He may deny that theories are abstract, or deny that they have an effect on world 1, or claim that abstract theories can directly affect the physical world. (I think, of course, that he would have a difficult time in defending any of these views.)

The second argument partly depends upon the first. If we admit the interaction of the three worlds, and thus their reality, then the interaction between worlds 2 and 3, which we can to some extent understand, can perhaps help us a little towards a better understanding of the interaction between worlds 1 and 2, a problem that is part of the mind-body problem.

For one kind of interaction between worlds 2 and 3 (‘grasping’) can be interpreted as a making of world 3 objects and as a matching of them by critical selection; and something similar seems to be true for the visual perception of a world 1 object. This suggests that we should look upon world 2 as active - as productive and critical (making and matching). But we have reason to think that some unconscious neurophysiological processes achieve precisely this. This makes it perhaps a little easier to ‘understand’ that conscious processes may act along similar lines: it is, up to a point, ‘understandable’ that conscious processes perform tasks similar to those performed by nervous processes.

A third argument bearing on the mind-body problem is connected with the status of human language.

The capacity to learn a language - and even a strong need to learn a language - are, it appears, part of the genetic make-up of man. By contrast, the actual learning of a particular language, though influenced by unconscious inborn needs and motives, is not a gene regulated process and therefore not a natural process, but a cultural process, a world 3 regulated process. Thus language learning is a process in which genetically based dispositions, evolved by natural selection, somewhat overlap and interact with a conscious process of exploration and learning, based on cultural evolution. This supports the idea of an interaction between world 3 and world 1; and in view of our earlier arguments, it supports the existence of world 2.

Several eminent biologists¹ have discussed the relationship between genetic evolution and cultural evolution. Cultural evolution, we may say, continues genetic evolution by other means: by means of world 3 objects.

It is often stressed that man is a tool-making animal, and rightly so. If by tools material physical bodies are meant, it is, however, of considerable interest to notice that none of the human tools is genetically determined, not even the stick. The only tool that seems to have a genetic basis is language. Language is nonmaterial, and appears in the most varied physical shapes - that is to say, in the form of very different systems of physical sounds.

There are behaviourists who do not wish to speak of ‘language’, but only of the ‘speakers’ of one or the other particular language. Yet there is more to it than that. All normal men speak; and speech is of the utmost importance for them; so much so that even a deaf, dumb and blind little girl like Helen Keller acquired with enthusiasm, and speedily, a substitute for speech through which she obtained a real mastery of the English language and of literature. Physically, her language was vastly different from spoken English; but it had a one-to-one correspondence with written or printed English. There can be no doubt that she would have acquired any other language in place of English. Her urgent though unconscious need was for language - language in the abstract.

As shown by their numbers and their differences, the various languages are manmade: they are cultural world 3 objects, though they are made possible by capabilities, needs, and aims which have become genetically entrenched. Every normal child acquires a language through much active work, pleasurable and perhaps also painful. The intellectual achievement that goes with it is tremendous. This effort has, of course, a strong feedback effect on the child’s personality, on his relations to other persons, and on his relations to his material environment.

Thus we can say that the child is, partly, the product of his achievement. He is himself, to some extent, a world 3 product. Just as the child’s mastery and consciousness of his material environment are extended by his newly acquired ability to speak, so also is his consciousness of himself. The self, the personality, emerges in interaction with the other selves and with the artefacts and other objects of his environment. All this is deeply affected by the acquisition of speech; especially when the child becomes conscious of his name, and when he learns to name the various parts of his body; and, most important, when he learns to use personal pronouns.

Becoming a fully human being depends on a maturation process in which the acquisition of speech plays an enormous part. One learns not only to perceive, and to interpret one’s perceptions, but also to be a person, and to be a self. I regard the view that our perceptions are ‘given’ to us as a mistake: they are ‘made’ by us, they are the result of active work. Similarly I regard it as a mistake

to overlook the fact that the famous Cartesian argument ‘I think, therefore I am’ presupposes language, and the ability to use the pronoun (to say nothing of the formulation of the highly sophisticated problem which this argument is supposed to settle). When Kant suggests that the thought ‘I think’ must be able to accompany all our perceptions and experiences, he does not seem to have thought of a child (or of himself) in his pre-linguistic or pre-philosophical state.²

What does world 3 look like from a materialistic point of view? Obviously, the bare existence of aeroplanes, airports, bicycles, books, buildings, cars, computers, gramophones, lectures, manuscripts, paintings, sculptures and telephones presents no problem for any form of physicalism or materialism. While to the pluralist these are the material instances, the embodiments, of world 3 objects, to the materialist they are simply parts of world 1.

But what about the objective logical relations which hold between theories (whether written down or not), such as incompatibility, mutual deducibility, partial overlapping, etc.? The radical materialist replaces world 2 objects (subjective experiences) by brain processes. Especially important among these are dispositions for verbal behaviour: dispositions to assent or reject, to support or refute; or merely to consider - to rehearse the pros and cons. Like most of those who accept world 2 objects (the ‘mentalists’), materialists usually interpret world 3 contents as if they were ‘ideas in our minds’: but the radical materialists try, further, to interpret ‘ideas in our minds’ - and thus also world 3 objects - as brain-based dispositions to verbal behaviour.

Yet neither the mentalist nor the materialist can in this way do justice to world 3 objects, especially to the contents of theories, and to their objective logical relations.

World 3 objects just are not ‘ideas in our minds’, nor are they dispositions of our brains to verbal behaviour. And it does not help if one adds to these dispositions the embodiments of world 3, as mentioned in the first paragraph of this section. For none of these copes adequately with the abstract character of world 3 objects, and especially with the logical relations existing between them.³

As an example, Frege’s Grundgesetze was written, and partly printed, when he deduced, from a letter written by Bertrand Russell, that there was a self-contradiction involved in its foundation. This self-contradiction had been there, objectively, for years. Frege had not noticed it: it had not been ‘in his mind’. Russell only noticed the problem (in connection with quite a different manuscript) at a time when Frege’s manuscript was complete. Thus there existed for years a theory of Frege’s (and a similar more recent one of Russell’s) which were objectively inconsistent without anyone’s having an inkling of this fact, or without anyone’s brain state disposing him to agree to the suggestion ‘This manuscript contains an inconsistent theory’.

To sum up, world 3 objects and their properties and relations cannot be reduced to world 2 objects. Nor can they be reduced to brain states or dispositions; not even if we were to admit that all mental states and processes can be reduced to brain states and processes. This is so despite the fact that we can regard world 3 as the product of human minds.

Russell did not invent or produce the inconsistency, but he discovered it. (He invented, or produced, a way of showing or proving that the inconsistency was there.) Had Frege’s theory not been objectively inconsistent, he could not have applied Russell’s inconsistency proof to it, and he would not have thus convinced himself of its untenability. Thus a state of Frege’s mind (and no doubt also a state of Frege’s brain) were the result, partly, of the objective fact that this theory was inconsistent: he was deeply upset and shaken by his discovery of this fact. This, in turn, led to his writing (a physical world 1 event) the words, ‘Die Arithmetik ist ins Schwanken geraten’ (‘Arithmetic is tottering’). Thus there is interaction between (1) the physical, or partly physical, event of Frege’s receiving Russell’s letter; (2) the objective hitherto unnoticed fact, belonging to world 3, that there was an inconsistency in Frege’s theory; and (3) the physical, or partly physical, event of Frege’s writing his comment on the (world 3) status of arithmetic.

These are some of the reasons why I hold that world 1 is not causally closed, and why I assert that there is interaction (though an indirect one) between world 1 and world 3. It seems to me clear that this interaction is mediated by mental, and partly even conscious, world 2 events.

I believe that the physicalist is also prevented from solving another problem: he cannot do justice to the higher functions of language.

This criticism of physicalism relates to the analysis of the functions of language that was introduced by my teacher, Karl Biihler. He distinguished three functions of language: (1) the expressive function; (2) the signalling or release function; and (3) the descriptive function. I have discussed Biihler’s theory in various places [for example, section iv of selection 4 above], and I have added to his three functions a fourth - (4) the argumentative function. Now I have argued elsewhere⁴ that the physicalist is only able to cope with the first and the second of these functions. As a result, if faced with the descriptive and the argumentative functions of language, the physicalist will always see only the first two functions (which are also always present), with disastrous results.

In order to see what is at issue, it is necessary to discuss briefly the theory of the functions of language.

In Buhler’s analysis of the act of speech he differentiates between the speaker (or, as Biihler also calls him, the sender) and the person spoken to, the listener (or the receiver). In certain special (‘degenerate’) cases the receiver may be missing, or he may be identical with the sender. The four functions here discussed (there are others, such as command, exhortation, advice - compare also Austin’s ‘performative utterances’⁵) are based on relations between

(1) the sender, (2) the receiver, (3) some other objects or states of affairs which, in degenerate cases, may be identical with (1) or (2). On the next page I will give a table of the functions in which the lower functions are placed lower and the higher functions higher. The following comments may be made on this table:

(1) The expressive function consists in an outward expression of an inner state. Even simple instruments such as a thermometer or a traffic light ‘express’ their states in this sense. However, not only instruments, but also animals (and sometimes plants) express their inner state in their behaviour. And so do men, of course. In fact,

animals, plants

man

any action we undertake, not merely the use of a language, is a form of self-expression.

(2) The signalling function (Biihler calls it also the ‘release function’) presupposes the expressive function, and is therefore on a higher level. The thermometer may signal to us that it is very cold. The traffic light is a signalling instrument (though it may continue to work during hours where there may not always be cars about). Animals, especially birds, give danger signals; and even plants signal (for example to insects); and when our self-expression (whether linguistic or otherwise) leads to a reaction, in an animal or in a man, we can say that it was taken as a signal.

(3) The descriptive function of language presupposes the two latter functions. What characterizes it, however, is that over and above expressing and communicating (which may become quite unimportant aspects of the situation), it makes statements that can be true or false: the standards of truth and falsity are introduced. (We may distinguish a lower half of the descriptive function where false descriptions are beyond the animal’s (the bee’s?) power of abstraction. A thermograph would also belong here, for it describes the truth unless it breaks down.)

(4) The argumentative function adds argument to the three lower functions, with its values of validity and invalidity.

Now, functions (1) and (2) are almost always present in human language; but they are as a rule unimportant, at least when compared with the descriptive and argumentative functions.

However, when the radical physicalist and the radical behaviourist turn to the analysis of human language, they cannot get beyond the first two functions.⁷ The physicalist will try to give a physical explanation - a causal explanation - of language phenomena. This is equivalent to interpreting language as expressive of the state of the speaker, and therefore as having the expressive function alone. The behaviourist, on the other hand, will concern himself also with the social aspect of language - but this will be taken, essentially, as affecting the behaviour of others; as ‘communication’, to use a vogue word; as the way in which speakers respond to one another’s ‘verbal behaviour’. This amounts to seeing language as expression and communication.

But the consequences of this are disastrous. For if all language is seen as merely expression and communication, then one neglects all that is characteristic of human language in contradistinction to animal language: its ability to make true and false statements, and to produce valid and invalid arguments. This, in its turn, has the consequence that the physicalist is prevented from accounting for the difference between propaganda, verbal intimidation, and rational argument.

From a Darwinian point of view, we are led to speculate about the survival value of mental processes. For example we might regard pain as a warning signal. More generally, Darwinists ought to regard ‘the mind’, that is to say mental processes and dispositions for mental actions and reactions, as analogous to a bodily organ (closely linked with the brain, presumably) which has evolved under the pressure of natural selection. It functions by helping the adaptation of the organism.⁸ The Darwinian view must be this: consciousness and more generally the mental processes are to be regarded (and, if possible, to be explained) as the product of evolution by natural selection.

The Darwinian view is needed, especially, for understanding intellectual mental processes. Intelligent actions are actions adapted to foreseeable events. They are based upon foresight, upon expectation; as a rule, upon short term and long term expectation, and upon the comparison of the expected results of several possible moves and countermoves. Hert preference comes in, and with it, the making of decisions, many of which have an instinctual basis. This may be the way in which emotions enter the world 2 of mental processes and experiences; and why they sometimes ‘become conscious’, and sometimes not.

The Darwinian view also explains at least partly the first emergence of a world 3 of products of the human mind: the world of tools, of instruments, of languages, of myths, and of theories. (This much can be of course also admitted by those who are reluctant, or hesitant, to ascribe ‘reality’ to entities such as problems and theories, and also by those who regard world 3 as a part of world 1 and/or world 2.) The existence of the cultural world 3 and of cultural evolution may draw our attention to the fact that there is a great deal of systematic coherence within both world 2 and world 3; and that this cun be explained - partly - as the systematic result of selection pressures. For example, the evolution of language can be explained, it seems, only if we assume that even a primitive language can be helpful in the struggle for life, and that the emergence of language has a feedback effect: linguistic capabilities are competing; they are being selected for their biological effects; which leads to higher levels in the evolution of language.

We can summarize this in the form of the following four principles of which the first two, it seems to me, must be accepted especially by those who are inclined towards physicalism or materialism.

(1) The theory of natural selection is the only theory known at present which can explain the emergence of purposeful processes in the world and, especially, the evolution of higher forms of life.

(2) Natural selection is concerned with physical survival (with the frequency distribution of competing genes in a population). It is therefore concerned, essentially, with the explanation of world 1 effects.

(3) If natural selection is to account for the emergence of the world 2 of subjective or mental experiences, the theory must explain the manner in which the evolution of world 2 (and of world 3) systematically provides us with instruments for survival.

(4) Any explanation in terms of natural selection is partial and incomplete. For it must always assume the existence of many (and of partly unknown) competing mutations, and of a variety of (partly unknown) selection pressures.

These four principles may be briefly referred to as the Darwinian point of view. I shall try to show here that the Darwinian point of view clashes with the doctrine usually called ‘epiphenomenalism’.

Epiphenomenalism admits the existence of mental events or experiences - that is, of a world 2 - but asserts that these mental or subjective experiences are causally ineffective byproducts of physiological processes, which alone are causally effective. In this way the epiphenomenalist can accept the physicalistic principle of the closedness of world 1, together with the existence of a world 2. Now the epiphenomenalist must insist that world 2 is indeed irrelevant; that only physical processes matter. If a man reads a book, the decisive thing is not that it influences his opinions, and provides him with information. These are all irrelevant epipheno-mena. What matters is solely the change in his brain structure that affects his disposition to act. These dispositions are indeed, the epiphenomenalist will say, of the greatest importance for survival: it is only here that Darwinism comes in. The subjective experiences of reading and thinking exist, but they do not play the role we usually attribute to them. Rather, this mistaken attribution is the result of our failure to distinguish between our experiences and the crucially important impact of our reading upon the dispositional properties of the brain structure. The subjective experiential aspects of our perceptions while reading do not matter; nor do the emotional aspects. All this is fortuitous, casual rather than causal.

It is clear that this epiphenomenalist view is unsatisfactory. It admits the existence of a world 2, but denies it any biological function. It therefore cannot explain, in Darwinian terms, the evolution of world 2. And it is forced to deny what is plainly a most important fact - the tremendous impact of this evolution (and of the evolution of world 3) upon world 1.

To put the matter in biological terms, there are several closely related systems of controls in higher organisms: the immune system, the endocrinal system, the central nervous system, and what we call the ‘mental system’. There is little doubt that the last

two of these are closely linked. But so are the others, if perhaps less closely. The mental system has, clearly, its evolutionary and functional history, and its functions have increased with the evolution from lower to higher organisms. It thus has to be linked with the Darwinian point of view. But epiphenomenalism cannot provide any link.

19 Natural Selection and Its

Scientific Status (1977)

i Darwin’s Natural Selection versus Paley’s Natural Theology