The new enemies of Rationalism

Dr. Altmann, Oxford

There was a time when we had no trouble in finding where the enemies of rationalism lurked. And because they normally operated outside the domains most concerned with rational thought, such conflicts as existed were easy to keep within clear boundaries. In the last thirty or forty years, instead, precisely those who profess to be its defenders, philosophers, mathematicians, and scientists, have effected concerted attacks against the fabric of rational thought.

As a result, the general public has been totally mystified. Even worse, the siren songs have been eagerly tuned to by social scientists, and since they are those most professionally engaged in communicating with the public, such truth as thus percolated to the media became tainted with wide misconceptions. We are witnessing a new trahison des clercs which, in an era of instant global communication, is many times more serious than anything experienced before. Curiously, some of the institutions that traditionally were seen as the enemies of rationalism are now amongst those that support, for instance, the position of science as a legitimate and independent seeker of truth. To think that while the Vatican has moved in this way, distinguished academic thinkers of famous universities have moved in entirely the opposite direction, is indeed awesome.

There are four strands to this academic attack on rationalism. First, philosophers have led the move, by debunking the most rational of British philosophers, David Hume. Secondly, mathematicians have flown to a Platonic empyrean, eagerly followed by philosophers engaged in dissociating mind processes from any possible resemblance to computers. Thirdly, theoretical physicists have made a meal of quantum mechanics, creating ‘paradoxes’ and ‘mysteries’ that have consumed whole forest of trees in popular expositions designed to encourage some sort of mysticism. What is even worse, a unique position for the human mind was claimed in quantum mechanics, implying in some way that perfectly natural processes cannot exist independently of an observing mind: Bishop Berkeley would have chuckled with delight.

The fourth strand is by far the most dangerous one, because it has been the most effective: the equation by Thomas Kuhn of science with one more myth, intellectually no better grounded than Aristotelian physics. And Thomas Kuhn has been the dominant influence in the history and philosophy of science in the last generation. If you go round Oxford, asking philosophical opinions about Kuhn, you hardly ever find an approving voice. But if you ask: what have you published to denounce this intellectual infirmity, silence befalls.

Why is Hume crucial in protecting a rational view of science? Not only Hume presented an original view of causality, but even to this day philosophers seem to ignore the fact that causality in science is not the same as in philosophy, and that Hume’s definitions are essential in the practice of modern science. ‘Short circuits cause fires in houses’: philosophers argue, correctly, that such a causal relation is neither necessary (arson would do) nor sufficient (solid-stone houses do not burn). Hume, however, insists in the causal relation being necessary and sufficient, a fact that even a pioneer of philosophy of science as Herschel knew in the early nineteenth century.

To cut the story short: a fundamental aspect of the science activity is the use of protocols. Those interested in the possible effects of short circuits on houses will specify a certain type of house and a certain type of environment, so that they can draw sensible conclusions from their studies. This is what philosophers call the ceteris paribus conditions (all else left unchanged), but for the scientist this is not an unfortunate constraint: it is the essence of their experimental skill.

The problem is much deeper. If you do not accept causality as necessary and sufficient, and you consider it distinctly plebeian to engage in ceteris paribus, then you must look for criteria to distinguish accidental from causal connections. Rom Harré, the Oxford philosopher, does this by means of ‘powers’, and Nancy Cartwright, of the London School of Economics, puts her money on ‘capacities’. Thus, a force has the power or the capacity to produce an acceleration. Very pretty, except that forces have a very precarious physical status. If your car stops suddenly and you do not wear a seat belt, you hit your head against the windscreen: the ‘force’ entailed is a fictional construction, required by the insistence in dealing with vectors, which change meaning in different coordinate systems, instead of tensors, that are far more robust entities. No, the insistence in powers and the like is a way back to Aristotle’s first causes: like them, it has no place whatsoever in modern scientific thought.

And now we come to the rub. Hume insisted that the causal relation is not observable: you observe connected events and it is the mind that establishes a relation. Hume referred to this activity of the mind as a ‘custom ‘ or ‘habit’, one of the ideas most misrepresented in the history of philosophy, because philosophers came with the view that this ‘custom’ was arbitrary and unstable.

In the 1960’s the American philosopher Ducasse cut the Gordian knot: the causal relation is actually perceived, contrary to Hume. When we see a brick breaking a glass window, we know that it is the brick that is doing the job, because nothing else is changing around the glass. This is extremely naive, since it obviously entails an implicit acceptance of the Leibniz principle of sufficient reason: but why should an event have to have a reason? And this is no rhetorical question, since in the study of the microworld there is no doubt that events may arise independently of causes.

Despite the flimsiness of Ducasse’s position, the idea that the causal relation is a percept was enthusiastically embraced by Harré and by Cartwright. But Hume himself has given us the lead to understand the problem. Because he never considered that the concept of ‘custom’ was just purely psychological and arbitrary. He calls it ‘the great guide of human life’ ... ‘necessary to the subsistence of our species’. Hume, in fact, was a proto-Darwinian.

We can now understand what he meant by custom. Our neural networks are systems wonderfully adapted to processing regularities. Their existence is both a consequence of such regularities in nature by the process of natural adaptation, and a testimony to the existence of such regularities, which therefore favour, in an evolutionary sense, organisms with the neural networks able to process them, and thus to act on causal principles. Once this new view of Hume’s causality is taken, enormously important ideas follow that fundamentally clarify rational thinking. The principles of causality, sufficient reason, and regularity or continuity are no longer enshrined in some realm of metaphysical principles: they are the result of our intercourse with nature (or at least such nature as we can perceive by means of our rational and perceptive systems). But the nature that has moulded such principles in our rational system is entirely macroscopic. No wonder that when the microworld is studied, absurd results arise if principles that have been tailored in a different environment are still applied without careful ‘editing’.

Reading Hume not having got rid of Aristotelian cobwebs has serious consequences for the interpretation of science. Nancy Cartwright has claimed that ‘the laws of physics lie’ (the title of one of her books, which has thus added some fuel to the pyre on which modern science has been exposed). The laws of nature cannot lie because they do not exist. We only have laws of models of nature. Newton laws, for instance, are applied to mathematical points: these are a map of nature, and everybody knows that to confuse the map with the object is nothing short of lunacy. The art of science is to map nature onto, say, nature(2), the model nature, and then produce laws for the latter. These laws allow us to predict ‘effect’ model objects, starting from their model ‘causes’. Once you apply a law that way, you must map back from the model ‘effect’ to its natural counterpart. Science thus entails an excursion from nature to nature(2). If this excursion is interrupted, you are left with a model object that need not have a counterpart in nature, and any attempt to map it back may lead to nonsense. This is a situation common in mathematical physics, especially when using a procedure called perturbation theory, in which the intermediate steps used in the models have no physical meaning. It is only the first (‘cause’) and the last (‘effect’) points in the excursion in model nature that must have counterparts in nature.

I shall now discuss the question of mathematical Platonism. There are, like in most religions, different orthodoxies of Platonism, but most mathematicians that embrace the doctrine claim, first, that mathematical objects form a world of their own, entirely independent of nature and of the human mind. Secondly, that mathematicians have a direct perception of mathematical objects, just as real as my perception of the table on which I am writing. I can justify my belief in my writing table because I can establish a causal chain from it to my perceptive system, photons, retina, nerves, synapses, and so on. But not even the most devout Platonist can attempt any such thing. I have asked Roger Penrose how he justifies this perception, and his answer is: it is a ‘mystery’. We all know that mysteries are wonderful for promoting sales, but indicate a total abdication of rationality.

The arch-Platonist of the twentieth century was Kurt Gödel, who discovered deep limitations to the properties of completeness or consistency of mathematico-logical systems. If you take completeness, for instance, a physicist who claimed that physical theory could in itself be complete – which entails that physical ‘proof’ be independent of nature – would have his or her sanity instantly questioned. In fact, what Gödel proved was that, just as you cannot give a complete closed account of why natural language is used the way it is used, so there cannot be a completely closed account of why mathematical propositions are accepted as true. In other words: he showed that we cannot walk without feet, whereupon he, like his followers, chose to levitate.

One of the most extravagant consequences of mathematical Platonism is the way in which it has affected the perception of the human mind. Everybody knows that when a mathematician has a creative moment, as when discovering a new theorem or, even better, a new mathematical concept, he or she achieves this, not by a routine, repetitive, (algorithmic) process but by what people appropriately call a leap of imagination. (Such as are shared by most creative people.)

This, however, is of no interest to the Platonists, because at that moment, for them, the mathematician is neither inventing nor creating: he or she is discovering, reading the Platonic world by such mysterious means as Penrose claims. On the other hand, such non-algorithmic thinking, they believe, must be demonstrated to occur when otherwise dealing with thinking-by-the-rules, i. e. doing algorithmic thinking. This is because it is the possibility of non-algorithmic thinking in such a case that should separate men from machines, as the Oxford philosopher John Lucas attempted to prove. Here the Gödel theorem comes handy, because his demonstration that no mathematical system is complete means that there are true statements that cannot be proved within the system, but which can be known to be true by mathematicians: herein Lucas expected to dig the chasm between men and machines. Penrose has very much exploited and extended Lucas’s idea and this is a corner stone of his recent works.

If you put this against the fact that we all know, in any case, that such non-algorithmic thinking is there as part of the creative process, the appeal to Gödel appears to complicate unnecessarily the discussion of intelligence. Again, there is here an attempt to study nature – of which intelligence is after all a part – without engaging with it. Wittgenstein had claimed that you cannot expect philosophy (or for that matter mathematics) to solve problems of natural science. But this wise precept is constantly forgotten by those who appear to yearn for a return to medieval forms of thought.

The reader might believe that the mathematical Platonist must have some form of mystical mind. The power of mathematics is so extraordinary, however, that it links as Platonists people of entirely opposite religious beliefs. Gödel himself had gone so far as to have produced once a logical proof of the existence of God, but the Cambridge mathematician G. H. Hardy, who was a staunch Platonist, held God to be his enemy.

The third strand that has propelled human thinking outside the safe paths of rationalism is quantum mechanics. Everybody knows these days that electrons, for instance, can behave some times as particles, some times as waves. Should we be surprised by this? Do we have to accept this as a ‘paradox’ from the mystery merchants? Of course not. What makes a macroscopic, that is, a classical particle, a particle, is that it has a trajectory. This solves pragmatically Berkeley’s problem: when I do not observe the moon, I can accept that it is there because it has a trajectory, which means that, if I know where it was at a certain time, I shall know where it will be at any later time. If you think of Berkeley’s famous unobserved tree, it also has a trajectory (stationary) and this is precisely why we understand what we mean when we say ‘there is a tree in my garden’. I do not have to keep observing it for it to be ‘there’.

The concept of a particle thus depends on that of trajectory, and the latter depends on some principle of uniformity or continuity. But I have already mentioned that, post-Hume, such principles are not carved in stone: they are the principles that both have directed the evolution of our cognitive system, and have emerged from the latter. But our cognitive system has never interacted with the microworld. Thus, we cannot assume continuity for electrons, we cannot have trajectories for them, and we cannot treat them as particles. So one ‘mystery’ less.

Einstein had been most significant, through his study of Brownian motion, in getting the scientific community to accept the concept of atoms and molecules, so abhorrent to Mach and his school. Now, Brownian motion is one of the best natural examples we have of random motion. Yet, Einstein abhorred the idea of randomness, to wit his famous dictum: God does not play with dice. Because quantum mechanics soon showed that there were inherent random, that is, non causal, processes in nature, Einstein mistrusted this theory almost obsessively, and his misgivings infected the minds of some of the cleverest theorists of our time, John Bell and David Bohm. Their work was important and useful, but they also created a feeling that quantum mechanics could not be a complete description of nature, because it depended too much on those damned random phenomena. Experiment after experiment was triumphantly proposed in the expectation that the nonsense behind quantum mechanics would be exposed, but, when they eventually were performed, quantum mechanics consistently came trumps. Yet, the despondent voices continue to this day, trying to fit the square peg of microscopic nature to the round hole of the macroworld.

Naturally, this is a recipe to display contradiction and paradox; and thus more ‘mysteries’ are thrown onto the public. How people can believe that the scientific process is a rational one, is difficult to understand when such a weave of contradictions is presented to them. But nature is never contradictory: it is us that abuse her by trying to dress her in the wrong clothes.

One of the unfortunate consequence of the barrage of complaints about quantum mechanics produced at the middle of last century is that it elicited the wrong responses from the guardians of the theory. The high priest of such a group was Niels Bohr who, to cover his back, as he thought, argued that quantum mechanics was a purely epistemological theory with no ontological claims at all. In other words, he was saying: trust me as a banker, because I give you any amount of paper money, of which I can produce as much as I want because it is my own creation, but please do not ask me what is there in the vaults of this bank. Of course, this created instant discomfort, eagerly exploited by the enemies of the theory. The strange ‘wave-particle’ that the electron was (which Eddington had christened ‘wavicle’), has no ontological status at all, it was claimed, following on Bohr’s steps. But David Bohm went further: for him the only objects that can have a proper ontology are ‘particles’ that, like the classical particles, can be described by means of proper and decent trajectories.

I cannot claim that these people are utterly wrong, because ontological claims have various levels of credibility. In physics, however, one takes the pragmatic view that when a theory saves the facts correctly, then the ‘objects’ of the theory, such as quarks, electrons, and so on, ‘exist’, that is, are ontologically licensed (as in fact the American philosopher Wilfred Sellars held). This means, of course, that they are credible objects that may be incorporated in further theories. So, orthodox quantum mechanics is as ontological as any other physical theory, the ‘wave-particles’ or ‘wavicles’ having the same ontological credentials as classical particles have within classical theory.

Bohr’s philosophical misconception, that quantum mechanics has no ontology, had the most confusing consequences when discussing the role of the observer in the theory. If an electron is purely epistemological, all we have is the act of observation, which is classical and ‘ontological’. But the act of observation requires an observer. Thus the quantum world is firmly tied up to the human mind as the point of closure of what, until the mind observes, has no more than an ontologically disadvantaged existence. Of course, measurement and observation are crucial in quantum mechanics, but the end of a measurement is macroscopic, the position of a pointer, say. You need as much the mind of the observer there as we need our mind to observe the moon and thus give it existence à la Berkeley.

I now come to the strongest attack that science ever experienced, and I write this with care: even Galileo’s inquisitor, Cardinal Roberto Bellarmino, held it possible, as he wrote in a memorandum to the Holy See, that the day might come when Galileo might be proved right. (Galileo himself admitted that he had no full proof of Copernican theory.) No such optimistic view of science-based knowledge was held by the most influential science historian of our generation, Thomas S. Kuhn. To paraphrase him, if Aristotelian dynamics or phlogiston chemistry are to be called myths, then myths are also produced and held by present scientific knowledge, and will always be so produced. This is the gist of what he says on p. 2 of the most influential book in the subject for a generation, The Structure of Scientific Revolutions, published in 1962.

Kuhnian philosophy of science is based on two strong assumptions. The first is that science at any one time depends on a body of principles and beliefs that are largely arbitrary (result of ‘human idiosyncrasy’) and disposable; and he called this body a paradigm. Secondly, paradigms change abruptly from time to time, through scientific revolutions, like the Copernican or Einsteinian revolutions.

If Kuhn had said that the so-called paradigms are contingent, then he would have been nearer the mark with respect to the structure of science; but then everything in this sublunar world is contingent, and such a claim would have been banal. Let me give an example that might go some way towards supporting his notion of ‘paradigm’, in the sense that science could at any one time proceed through alternative modes of description. Newton’s dynamics was based on two independent variables, space and time. The velocity, instead, is given by space divided by time. But Newton could have used a Doppler gauge, which reads instantaneous velocities. Classical mechanics could thus have been based on two different independent variables, space and velocity. Time would then have been given as space divided by velocity: no need for clocks! Why we never went through such a ‘paradigm’?

The answer is quite simple: concepts in science evolve, and in evolutionary systems each step depends on the previous history. Thus, it would not have been possible to design Doppler gauges not having had previous access to Newtonian physics. Science has to start from approximate observations and theories, and build on them progressively. Kuhn’s paradigm is just as idiosyncratic as the human eye is idiosyncratic: it is what it is because of its previous evolutionary theory. Of course, it is contingent, but to say that the human eye could have been entirely different, say infrared-sensitive, is useless. In an evolutionary process, although the evolutionary histories are contingent, every intermediary step entails an element of necessity, insofar as the original step from which any evolutionary process arises is a fixed datum that can as much be changed as we could change the date of the battle of Hastings.

Science, in fact, creates no arbitrary paradigms, but a mesh of facts and theories that must all fit together at any one time. This fitting, following Nelson Goodman, I have called entrenchment. Some elements of the mesh maybe precariously entrenched. Others will be very well entrenched because they fit a very wide range of elements of the mesh. Contrary to Kuhn, the mesh is not rendered asunder by revolutions. Just as the human eye did not evolve in a single revolutionary step from a piece of skin, so the science mesh evolves, never shedding entirely well-entrenched theories, but defining every time more precisely the domains of the mesh upon which they may be applied.

Thus, relativity theory did not destroy Newtonian mechanics. It did not even replace it: it merely stated the errors that the use of Newtonian theory would entail as a function of the velocities. In fact, it showed that such errors are negligible for most the velocities we are likely to encounter with macroscopic objects on earth. Einstein himself rejected the view that he was a revolutionist. The whole purpose of his first paper on special relativity was to save Maxwell’s electromagnetic theory. To put it in a nutshell: this theory contained only one parameter that could be identified with the velocity of light. Hence, the velocity of light had to be constant, independent of the state of motion of the emitter and of the direction of propagation. From this concept, the whole of special-relativity mechanics arose.

Yes, of course: there was a relativistic revolution, but this was philosophical and not scientific. From Einstein onwards, Kant-style armchair study of space and time was finished. A whole chunk of human thought was taken away from philosophy and became physics.

Surely, we all speak of the Copernican revolution. But this was theological, not physical. If you think about it, whether the earth is or is not the centre of the solar system is of course a very important fact, but from the point of view of physical theory less significant than the principle of inertia. It was this principle that, allowing for motion without an Aristotelian first cause, permitted dynamics to be divorced from animistic preconceptions. What Copernican theory did, was to remove a whole chunk of physical knowledge from the hands of the theologians: Genesis was no longer authority in astronomical studies, as Bellarmino himself felt the time might come when this would be the case. And the whole thing clearly ended when Vatican Council II permitted the reading of the scriptures as metaphorical. As for Newton removing the need of a first cause for the movement of the celestial bodies, that this had serious implications on theology is evident from Leibniz’s 1715 letter to Caroline, Princess of Wales, when he expressed his concern that Newton’s views (not Copernicus’) would destroy belief.

The damage that Kuhn’s views on science has done is unprecedented, as coming from a distinguish academic. Of course, scientists have gone their own way, but Kuhn's ideas have been eagerly taken up by many social scientists, thus creating forms of cultural relativism that have done nothing else than confuse rational thought. I must stress that cultural relativism properly understood is both legitimate and important. The voodoo paradigm may be totally valid as a form of expression of a certain society, but to claim that it has the same standing as the scientific paradigm, to follow with Kuhn’s terminology, is entirely wrong. What may be valid and important for one form of activity may be absurd in another. Van Gogh was an outstanding painter, but, were he alive, would you fly in an airplane piloted by him? There are cultures and there are activities. Of course, across different cultures, some activities, like medicine, might somewhat change. But there are certain activities that must transcend cultures: rational thinking is one of them. I am fully aware that this is still only a hope: I wish it were a programme. And for this to be so, academics should shoulder this enormous responsibility, instead of obscuring matters with dubious philosophies.

Dr. Altmann’s paper is based on his forthcoming book Is Nature Supernatural? A Philosophical Exploration of Science and Nature, (Prometheus Books, Amherst, ca. December 2001), where all the necessary references and detailed arguments may be found. A very important attack on Kuhn was published, after his book was finished, by the Austin, Texas, physicist Stephen Weinberg in Number 15 of The New York Review of Books, November 1998. In an unprecedented event, the British Institute of Physics had a leader on this article in its own journal.