Most Chinese and Indian contributors to the debate agreed. In the third century bce, however, Gongsun Long, a self-professed student of ‘the ways of former kings’, or, as we might now say, an historian, coined a startling apophthegm, ‘A white horse is not a horse’,36 to express a profound problem: our senses, as far as they are reliable, assure us that the white horse exists, along with a lot of other particular creatures we call horses; but what about the horse referred to by the general term – the ‘horse of a different colour’, who is not grey or chestnut or palomino or differentiated by any of the particularities that mark one horse as different from others? Critics called Gongsun Long’s paradox ‘jousting with words’, but it has unsettling implications. It suggests that maybe only the particular horse really exists and that general terms denote nothing real. The universe becomes incomprehensible, except patchily and piecemeal. Supposedly universal truths dissolve. Universal moral precepts crumble. Aspiringly universal empires teeter. The doctrine has inspired radicals in every age since its emergence. In the sixteenth and seventeenth centuries it helped Luther challenge the Church, and pitted individualists against old, organic notions of society. In the twentieth century, it has fed into existentialist and postmodern rebellion against the idea of a coherent system in which everyone has a place.
Nominalism, as the doctrine came to be called, showed how hard it is to formulate truth – to devise language that matches reality: so hard, indeed, that some sages proposed dodging it. Truth is an abstract idea, but a practical matter: we want decisions and actions to have a valid basis. But how do we choose between rival formulations? Protagoras became notorious in ancient Greece for dismissing the question on the grounds that there is no objective test. ‘Man’, he said, ‘is the measure of all things, of the existence of the things that are, and the nonexistence of things that are not.’ Socrates – the voice of wisdom in Plato’s dialogues – knew exactly what this puzzling statement meant: relativism – the doctrine that truth for one person is different from truth for another.37 There were relativists in ancient China, too. ‘Monkeys prefer trees’, Zhuangzi pointed out early in the third century bce, ‘so what habitat can be said to be absolutely right? Crows delight in mice, fish flee at the sight of women whom men deem lovely. Whose is the right taste absolutely?’38
Most thinkers have been unwilling to accept that although relativism may apply in matters of taste, it cannot be extended to matters of fact. The modern philosopher Roger Scruton put the key objection neatly: ‘The man who says, “There is no truth” is asking you not to believe him. So don’t’, or in an equally amusing paradox of the Harvard logician, Hilary Putnam, ‘Relativism just isn’t true for me.’39 Those who prefer, however, to stick with Protagoras have been able to embrace radical conclusions: everyone has his or her own reality, as if each individual embodied a separate universe; truth is just a rhetorical flourish, an accolade we give to utterances we approve, or a claim we make to suppress dissenters. All views are equally valueless. There are no proper arbiters of conflicts of opinion – not bishops, not kings, not judges, not technocrats. Populism is therefore the best politics. Sages who wanted to answer relativism often appealed to numbers: five flowers are real. What about five? Isn’t that real, too? Wouldn’t numbers exist even if there were nothing to count? To judge from tallies notched on sticks or scratched on cave walls in Palaeolithic times, counting came easily to humans as a way of organizing experience. But mathematics offered more: a key to an otherwise inaccessible world, more precious to those who glimpse it in thought than the world we perceive through our senses. Geometry showed how the mind can reach realities that the senses obscure or warp: a perfect circle and a line without magnitude are invisible and untouchable, yet real. Arithmetic and algebra disclosed unreachable numbers – zero and negative numbers, ratios that could never be exactly determined, yet which seemed to underpin the universe: π, for instance (22 ÷ 7), which determined the size of a circle, or what Greek mathematicians called the Golden Number ([1 + √5] ÷ 2), which seemed to represent perfection of proportion. Surds, such as the square root of two, were even more mysterious: they could not be expressed even as a ratio (and were therefore called irrational).
Pythagoras was a crucial figure in the history of the exploration of the world of numbers. Born on an Ionian island around the middle of the sixth century bce, he spanned the Greek world, teaching, for most of his life, in a colony in Italy. He attracted stories: he communed with the gods; he had a golden thigh (perhaps a euphemism for an adjacent part of the anatomy). To his followers he was more than a mere man but a unique being, between human and divine. Two relatively trivial insights have made him famous to modern schoolchildren: that musical harmonies echo arithmetical ratios, and that the lengths of the sides of right-angled triangles are always in the same proportions. His real importance goes much deeper.
He was the first thinker, as far as we know, to say that numbers are real.40 They are obviously ways we have of classifying objects – two flowers, three flies. But Pythagoras thought that numbers exist apart from the objects they enumerate. They are, so to speak, not just adjectives but nouns. He went further: numbers are the architecture by which the cosmos is constructed. They determine shapes and structures: we still speak of squares and cubes. Numerical proportions underlie all relationships. ‘All things are numbers’41 was how Pythagoras put it.
In his day civilization was still carving fields and streets from nature, stamping a geometric grid on the landscape. So Pythagoras’s idea made sense. Not all sages shared his view: ‘I sought the truth in measures and numbers’, said Confucius, according to one of his followers, ‘but after five years I still hadn’t found it.’42 But the reality of numbers became entrenched in the learned tradition that spread from ancient Greece to the whole of the Western world. In consequence, most people have accepted the possibility that other realities can be equally invisible, untouchable, and yet accessible to reason: this has been the basis of an uneasy but enduring alliance between science, reason, and religion.
Rationalism and Logic
If you do believe that numbers are real, you believe that there is a supersensible world. ‘It is natural’, as Bertrand Russell said, ‘to go further and to argue that thought is nobler than sense, and the objects of thought more real than those of sense-perception.’43 A perfect circle or triangle, for instance, or a perfectly straight line, is like God: no one has ever seen one, though crude man-made approximations are commonplace. The only triangles we know are in our thoughts, though the versions we draw on paper or blackboard merely help call them to mind, as a Van Gogh sky suggests starlight, or a toy soldier suggests a soldier. Maybe the same is true of everything. Trees may be like triangles. The real tree is the tree we think of, not the tree we see.
Thought needs no objects outside itself: it can make up its own – hence the creative power some sages credited it with. Reason is chaste rationalism, unravished by experience. That is what Hui Shi thought. He was China’s most prolific writer of the fourth century bce. His books filled cartloads. He uttered numbing, blinding paradoxes: ‘Fire is not hot. Eyes do not see.’44 He meant that the thought of fire is the only really hot thing we genuinely know about and that data act directly on the mind. Only then do we sense them. What we really see is a mental impression, not an external object. We encounter reality in our minds. Unaided reason is the sole guide to truth.
Of those we know by name, the first rationalist was Parmenides, who lived in a Greek colony of southern Italy in the early fifth century bce, striving for self-expression in poetry and paradox. He endured – the way I imagine him – the agony of a great mind imprisoned in imperfect language, like an orator frustrated by a defective mike. He realized that what we can think limits what we can say, and is restricted in turn by the range of the language we can devise. On the only route to truth, we must bypass what is sensed in favour of what is thought. The consequences are disturbing. If, say, a pink rose is real by virtue of being a thoug
ht rather than a sensible object, then a blue rose is equally so. If you think of something, it really exists. You cannot speak of the nonexistence of anything.45 Few rationalists are willing to go that far, but reason does seem to possess power that observation and experiment cannot attain. It can open those secret caverns in the mind, where truths lay buried, unblemished by the disfigurements on the walls of Plato’s cave. The idea contributed all that was best and worst in the subsequent history of thought: best, because confidence in reason made people question dogma and anatomize lies; worst, because it sometimes inhibited science and encouraged self-indulgent speculation. Overall, the effects have probably been neutral. In theory, reason should inform laws, shape society, and improve the world. In practice, however, it has never had much appeal outside elites. It has rarely, if ever, contributed much to the way people behave. In history books, chapters on an ‘Age of Reason’ usually turn out to be about something else. Yet the renown of reason has helped to temper or restrain political systems founded on dogma or charisma or emotion or naked power. Alongside science, tradition, and intuition, reason has been part of our essential toolkit for discovering truths.
For some rationalists, reason became an escapist device – a way of overtrumping or belittling the irksome world we actually inhabit. The most extreme case of the use of reason to mock the cosmos was the paradox-enlivened mind of Zeno of Elea, who preceded Hui Shi’s paradoxes with similar examples of his own. He travelled to Athens around the middle of the fifth century bce to show off his technique, stun complacent Athenians, and confound critics of his master, Parmenides. He paraded, for example, the infuriating argument that an arrow in flight is always at rest, because it occupies a space equal to its own size. According to Zeno, a journey can never be completed, because half the remaining distance has always to be crossed before you get to the end. In an example startlingly like one of Hui Shi’s – who pointed out that if a strip of bamboo is halved every day it will last forever – Zeno quipped that matter must be indivisible: ‘If a rod is shortened every day by half its length, it will still have something left after ten thousand generations.’46
His impractical but impressive conclusions drove reason and experience apart. Other sages tried to plug the gap. The best representative of the attempt was Aristotle, a physician’s son from northern Greece, who studied with Plato and, like all the best students, progressed by dissenting from his professor’s teachings. Walter Guthrie, the Cambridge scholar whose knowledge of Greek philosophy no rival ever equalled, recalled how at school he was made to read Plato and Aristotle. Plato’s prose impressed him equally for its beauty and unintelligibility. But even as a boy, he was amazed that he could understand Aristotle perfectly. He supposed that the thinker was ‘ahead of his day’, miraculously anticipating the thought of young Walter’s own time. Only when Guthrie grew into maturity and wisdom did he realize the truth: it is not because Aristotle thought like us that we understand him, but because we think like Aristotle. Aristotle was not modern; rather, we moderns are Aristotelian.47 He traced grooves of logic and science in which our own thoughts still circulate.
The process that led to logic started around the middle of the first millennium bce, when teachers in India, Greece, and China were trying to devise courses in practical rhetoric: how to plead in courts, argue between embassies, persuade enemies, and extol patrons. Rules for the correct use of reason were a by-product of the persuaders’ art. But, as Christopher Marlowe’s Faustus put it, ‘Is to dispute well logic’s chiefest end? Affords this art no greater miracle?’ Aristotle proposed purer ends and contrived a greater miracle: a system for sorting truth from falsehood, strapping common sense into practical rules. Valid arguments, he showed, can all be analysed in three phases: two premises, established by prior demonstration or agreement, lead, as if with a flourish of the conjurer’s wand, to a necessary conclusion. In what has become the standard textbook example of a ‘syllogism’, if ‘All men are mortal’ and ‘Socrates is a man’, it follows that Socrates is mortal. The rules resembled mathematics: just as two and two make four, irrespective of whether they are two eggs and two irons, or two mice and two men, so logic yields the same results, whatever the subject matter; indeed, you can suppress the subject matter altogether and replace it with algebraic-style symbols. Meanwhile, in India, the Nyaya school of commentators on ancient texts were engaged on a similar project, analysing logical processes in five-stage breakdowns. In one fundamental way, however, they differed from Aristotle: they saw reason as a kind of extraordinary perception, conferred by God. Nor were they strict rationalists, for they believed that rather than arising in the mind, meaning derives from God, Who confers it on the objects of thought by way of tradition, or consensus. Clearly, logic is imperfect in as much as it relies on axioms: propositions deemed to be true, which cannot be tested within the system. But after Aristotle there seemed nothing much left for Western logicians to do, except refine his rules. Academic overkill set in. By the time the refiners had finished, they had classified all possible logical arguments into 256 distinct types.48
There should be no conflict between reason and observation or experience: they are complementary ways of establishing truth. But people take sides, some mistrusting ‘science’ and doubting the reliability of evidence, others rejecting logic in favour of experience. Science encourages distrust of reason by putting experiment first. As the senses are unreliable, according to rationalists’ way of looking at things, observation and experience are inferior arts: the best laboratory is the mind and the best experiments are thoughts. Rationalism, on the other hand, in an uncompromisingly scientific mind, is metaphysical and unrooted in experience.
The Retreat from Pure Reason: Science, Scepticism, and Materialism
Thinkers of the first millennium bce juggled science and reason in their efforts to get out of Plato’s cave. In the conflicts that arose, we can discern the origins of the culture wars of our own time, which pit dogmatic science – ‘scientism’, as opponents call it – against spiritual styles of thinking. At the same time, sceptics cultivated doubts about whether any technique could expose the limits of falsehood. Between reason and science, a gap opened that has never been re-bridged.
In one sense, science begins with a form of scepticism: mistrust of the senses. It aims to penetrate surface appearances and expose underlying truths. The third-century encyclopaedia Lushi Chunqiu – one of the precious compendia of the time, designed to preserve Chinese learning from hard times and barbarian predators – points out instructive paradoxes. Metals that look soft can combine in hard alloys; lacquer feels liquid but the addition of another liquid turns it dry; apparently poisonous herbs can be mixed to make medicine. ‘You cannot know the properties of a thing merely by knowing those of its components.’49
Nonetheless, like all text we class as scientific, Lushi Chunqiu focused on identifying what is reliable for practical purposes. The supernatural does not feature, not because it is false but because it is useless and unverifiable. When Aristotle demanded what he called facts, rather than mere thoughts, he was in intellectual rebellion against the arcane refinements of his teacher, Plato. But a deeper, older revulsion was also at work in the science of the era, which rejected appeals to invisible and undetectable spirits as the sources of the properties of objects and the behaviour of creatures (see here). Spirits inhibited science: they could be invoked to explain changes otherwise intelligible as the results of natural causes.
As far as we can tell, before the first millennium bce no one drew a line between what is natural and what is supernatural: science was sacred, medicine magical. The earliest clear evidence of the distinction occurred in China in 679 bce, when the sage Shenxu is said to have explained ghosts as exhalations of the fear and guilt of those who see them. Confucius, who deterred followers from thinking ‘about the dead until you know the living’,50 recommended aloof respect for gods and demons. For Confucians, human affairs – politics and ethics – took precedence over the rest
of nature; but whenever they practised what we call science they challenged what they regarded as superstition. They denied that inanimate substances could have feelings and wills. They disputed the notion that spirits infuse all matter. They derided the claim – which even some sophisticated thinkers advanced on grounds of cosmic interconnectedness – that the natural world is responsive to human sin or rectitude. ‘If one does not know causes, it is as if one knew nothing,’ says a Confucian text of about 239 bce. ‘The fact that water leaves the mountains is not due to any dislike on the part of the water but is the effect of height. The wheat has no desire to grow or be gathered into granaries. Therefore the sage does not enquire about goodness or badness but about reasons.’51
Natural causes, in varying degrees in different parts of Eurasia, displaced magic from the arena of nature in erudite discourse. Science could not, however, desacralize nature entirely: the withdrawal of spirits and demons left it, in most sages’ minds, in the hands of God. Religion retained an irrepressible role in establishing humans’ relations with their environments. In China, emperors still performed rites designed to maintain cosmic harmony. In the West, people still prayed for relief from natural disasters and imputed afflictions to sins. Science has never been perfectly separated from religion: indeed, each of these approaches to the world has impertinently colonized the other’s territory. Even today, some hierophants try to tamper with the scientific curriculum, while some scientists advocate atheism as if it were a religion, evolution as if it were Providence, and Darwin as if he were a prophet.
Out of Our Minds Page 18
