Karl Popper

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Karl Popper

(1902-1994)

Popper wrote extensively on the problem of determinism and free will, researched many earlier thinkers on the subject, and formulated his own "evolutionary" model of free will. In his Arthur Holly Compton lecture, Of Clouds and Clocks, delivered at Washington University in St. Louis in April 1965, he noted that earlier thinkers had seen the only alternative to determinism as chance.

This is the classic argument against free will, that it comes to a stark choice between determinism or indeterminism.

Hume found nothing between chance and necessity, and Eddington had said, there is "no halfway house" between randomness and determinism.

But note that Popper may have been inspired by Arthur Holly Compton himself, who said an "act of choice [adds] a factor not supplied by the physical conditions...determining what will occur." See Compton's Atlantic Monthly article.

In his dialogues with John Eccles, (The Self and Its Brain, 1977), at first Popper dismissed quantum mechanics as being no help with free will, but later describes a two-stage model that parallels Darwinian evolution, with genetic mutations being probabilistic and involving quantum uncertainty.

"People who do not agree with determinism are usually viewed with suspicion by rationalists who are afraid that if we accept indeterminism, we may be committed to accepting the doctrine of Free Will, and may thus become involved in theological arguments about the Soul and Divine Grace. I usually avoid talking about free will, because I am not clear enough about what it means, and I even suspect that our intuition of a free will may mislead us. Nevertheless, I think that determinism is a theory which is untenable on many grounds, and that we have no reason whatever to accept it. Indeed, I think that it is important for us to get rid of the determinist element in the rationalist tradition. It is not only untenable, but it creates endless trouble for us. It is, for this reason, important to realize that indeterminism - that is, the denial of determinism - does not necessarily involve us in any doctrine about our 'will' or about 'responsibility'. (Popper, Conjectures and Refutations, 1962, Harper, 1968, p.123)

"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'.
"I shall later argue against this important doctrine according to which the 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 jug-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 altenative 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.)" (Objective Knowledge, Of Clouds and Clocks, 1972, p. 227ff)

Popper replying to John Eccles:

"First of all, I do of course agree that quantum theoretical indeterminacy in a sense cannot help, because this leads merely to probabilistic laws, and we do not wish to say that such things as free decisions are just probabilistic affairs.
"The trouble with quantum mechanical indeterminacy is twofold. First, it is probabilistic, and this doesn't help us much with the free-will problem, which is not just a chance affair. Second, it only gives us indeterminism, not openness to World 2 [Popper's Mind World]. However, in a roundabout way I do think that one may make use of quantum theoretical indeterminacy without committing oneself to the thesis that free-will decisions are probabilistic affairs.

(Popper and Eccles, The Self and Its Brain, 1977, p.540)

Here Popper compares new ideas to variation in the gene pool due to random mutations followed by natural selection, as William James had done in 1880.

"New ideas have a striking similarity to genetic mutations. Now, let us look for a moment at genetic mutations. Mutations are, it seems, brought about by quantum theoretical indeterminacy (including radiation effects). Accordingly, they are also probabilistic and not in themselves originally selected or adequate, but on them there subsequently operates natural selection which eliminates inappropriate mutations. Now we could conceive of a similar process with respect to new ideas and to free-will decisions, and similar things.

Here Popper clearly conceptualizes the two-stage Cogito model already seen by James and Poincaré over fifty years earlier
That is to say, a range of possibilities is brought about by a probabilistic and quantum mechanically characterized set of proposals, as it were - of possibilities brought forward by the brain. On these there then operates a kind of selective procedure which eliminates those proposals and those possibilities which are not acceptable to the mind, anchored in World 3 [the world of human knowledge and artifacts, our Sum], which tries them out in World 3 and checks them by World 3 standards. This may perhaps be the way in which these things take place, and it was for this reason that I so much liked the suggestion about the inhibitory neurones working like a sculptor who cuts away and discards part of the stone in order to form his statue.

(Popper and Eccles, The Self and Its Brain, p.540)

A few years earlier, Popper had called for a combination of randomness and control to explain freedom, though not yet explicitly, as is needed, in two stages with random chance before a controlled decision.

"freedom is not just chance but, rather, the result of a subtle interplay between something almost random or haphazard, and something like a restrictive or selective control"
(Objective Knowledge, Of Clouds and Clocks, 1972, p. 232)

For those extreme libertarians who prefer a traditional definition of freedom as pure chance (liberum arbitrium indifferentiae), we can offer free will as Popper's interplay between chance and control (based on Compton's simple view of "chance, then choice").

In 1977 Popper gave the first Darwin Lecture, at Darwin College, Cambridge. He called it Natural Selection and the Emergence of Mind. In it he said he had changed his mind (a rare admission by a philosopher) about two things. First he now thought that natural selection was not a "tautology" that made it an unfalsifiable theory. Second, he had come to accept the random variation and selection of ideas as a model of free will.

The selection of a kind of behavior 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 that quantum indeterminacy does not seem to help us;¹ 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.

This is now the leading two-stage model of free will.
I have changed my mind on this issue.² 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.

1. Cf. my Objective Knowledge, chapter 6, pp. 226-29.
2. See p. 540 of J. C. Eccles and K. R. Popper, The Self and Its Brain (Berlin, Heidelberg, London, New York: Springer-Verlag, 1977).

Six years later, Popper wrote some very insightful and critical remarks on knowledge in lower and higher organisms. As we argue in information philosophy, biological information processing systems use their knowledge to achieve their purposes, primarily advancing themselves and their species in the struggle for survival.

With life, purpose (telos) entered the universe.
All organisms are professional problem solvers: before life, problems did not exist. Problems and life entered the world together, and with them problem solving. At first, the problems were sheer survival problems: an organism was, at first, just a professional survivor. In time this changed, and a problem today may be for some people a vastly different thing: it may be "How did life originate?" or perhaps "In which of his dialogues, if in any, does Plato attempt to portray Socrates?" - this is obviously not a survival problem.

As Konrad Lorenz noted, everything a priori for the individual is a posteriori for the species.
The problems may be created by the clash of the organism with its environment. But the tentative solutions, the trial and the errors all come from, the organism. They are all a priori, even though the environment constantly plays its part, of course.
The view which I am trying to make attractive to you is, I am afraid, utterly different from those views which are at present held by almost everybody and which I have described, for the past 60 years, as the "bucket theory of the mind" (die Kübeltheorie des Geistes). But today an inventor theory of the mind and a discovery theory of the mind and a searchlight theory of the mind ought to be a little more acceptable than they were 60 years ago...

Descartes's view of the human mind was more than stimulus/response. But even the lowest animals use their built-in, evolved knowledge to survive.
See Brian Goodwin's Cognitive Biology.
I find it of the greatest importance to get over the myth (for it seems to me a myth) that anything starts with a stimulus and the ability to respond to it. Everything, I suggest, starts from the organism and its eagerness, its need, which seeks for anything it can use as a message, as information or as a so-called stimulus: I am not quarrelling about words, I am insisting upon the obvious fact that it is not its capability of being stimulated which makes the organism, but the exploratory apparatus, the keenness to respond, which makes the stimulus. It is the organism which, through many trials over millions of generations, learns to respond to this kind or that kind of stimulus: it turns something into a stimulus; it invents the ability to "see" this or that, but it may do all this a priori, by a mutation which, in its turn, may be due to its mutationally acquired mutability.
I am a Darwinist and I am not a vitalist or a Lamarckist. I agree that the organism's aims and preferences may be conjectured to be the result of natural selection. But once they exist, they are of immense significance in evolution. The idea that environmental conditions do all the sculpturing by carving away what is less fit, and that the organism is passive, is simply false from an evolutionary point of view. Without the organism's struggle for survival there would be no evolution. And this means that it is only the organism's fight for life, its problem solving, its constant search for a better environment, for better living conditions, its active evolution of its own preferences, of its sensitivity, that makes evolution possible. It is the only active agent. It is the environment which is passive. To look at it as hostile, as so many Darwinists do, is mistaking a metaphor for a powerful reality. To think of it as a sculptor, a carver, is to make a god of it. It is always the organism which seeks a better ecological niche, better living conditions, a better life. All else is metaphor.
The biologist, observing, experimenting, begins with the stimulus. And he is in danger of believing in the famous couple: stimulus and response. But it is the organism which evolves all sorts of responses to find, interpret, exploit and learn from what we mistakenly look upon as the life-evoking, life-demonstrating stimulus of a (perhaps even passive) response...
I wish to end with an important proposition. The difference between the growth of animal knowledge and of human knowledge is just this: human language permits us to formulate our theories outside our skin, exosomatically: this allows us to criticize them. This makes possible the evolution of human reason, of the use of imagination and of criticism in the search for truth.

"Critical Remarks on the Knowledge of Lower and Higher Organisms, the So-Called Sensory Motor Systems," in Sensory-Motor Integration in the Nervous System, Creutzfeld, O.; Schmidt, R. F.; Willis, W. D. (Eds.), Springer, 1984, p.28-30. Thanks to Aaron Sloman for this reference.

The aggregation of human knowledge embodied externally - "exosomatically" as Popper puts it - is the core idea of the Sum in information philosophy. It is not chauvinistic or parochial to regard it as the highest form of evolved information in the universe. Nor is it naive to regard it as proof of the Idea of Progress and a possible basis for objective value.

Natural Selection and the Emergence of Mind

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