The pre-Socratic philosopher sparked an intellectual revolution that still echoes today. Yet for philosophy and science to continue to progress in the 21st century, we may need to embark on an entirely new cognitive journey
January 20, 2008

Alfred North Whitehead famously described the European philosophical tradition as "a series of footnotes to Plato." Whether or not this is fair to the thinkers that followed Plato, it is a gross injustice to those that preceded him. Pre-eminent among these was Parmenides. Elizabeth Anscombe's riposte that Plato might be regarded as "Parmenides's footnote" is not as perverse as it seems. While Plato's dialogues are among the supreme philosophical works of the western tradition, it was Parmenides who established the implicit framework of their debates.

Plato acknowledged that Parmenides had "magnificent depths." But there is more to Parmenides than this: in his thought, human consciousness had a crucial encounter with itself. This was, I believe, a decisive moment in the long awakening of the human species to its own nature. From this self-encounter resulted the cognitive self-criticism, the profound critical sense that gave birth to the unfolding intellectual dramas of metaphysics and science that have in the last century or so approached an impasse.

Compared with Socrates, through whom Plato ventriloquised his own thoughts in a series of dramatised dialogues, Parmenides remains a shadowy figure. Pretty well all we know of him is that he was a handsome patrician, born in Elea in southern Italy "of a rich and honourable race" (in Hegel's words), and that he flourished in the first part of the 5th century BC. It took another genius, Nietzsche, to make Parmenides live as a human being.

Nietzsche saw that Parmenides was the pivotal figure of the period between 600 and 400 BC, when the history of explicitly rational thought had its beginning. In his wonderful little book Philosophy in the Tragic Age of the Greeks, Nietzsche imagined the "moment of purest, absolutely bloodless abstraction, unclouded by any reality" at which Parmenides arrived at his vision of the world. He admired Parmenides as one of those true thinkers who were prepared, as he put it in Thus Spake Zarathustra, "to feed on the acorns and grass of knowledge and for the sake of truth suffer hunger of the soul." He attributes a prayer to him: "Grant me, ye gods… but one certainty [even] if it be but a log's breadth on which to lie, on which to ride upon the sea of uncertainty. Take away everything that comes-to-be, everything lush, colourful, blossoming, illusory… Take all these for yourselves and grant me but the one and only, poor empty certainty."

One attraction of Parmenides is that you can read his complete surviving works in 15 minutes. His arguments are set out in On Nature, a rather prosaic poem of which only 150 lines survive. The heart of his case is in Fragments 3, 6 and 8, where he sets out a worldview that even by the standards of philosophy is, as Aristotle said, "near to madness." His central argument is so quick that if you blink, you will miss it.

It goes as follows. That which is not, is not. "What-is-not" does not exist. Since anything that comes into being must arise out of what-is-not, objects, states of affairs and so on cannot come into being. Likewise, they cannot pass away, because in order to do so they would have to enter the realm of what-is-not. Since it does not exist, what-is-not cannot be the womb of generation, or the tomb of that which perishes. The no-longer and the not-yet are variants of what-is-not, and so the past and future do not exist either. Change, then, is impossible. Equally, multiplicity is unreal. The empty space necessary to separate one object from another would be another example of what-is-not. And since things cannot be anything to a greater or lesser degree—this would require what-is to be mixed with the diluting effect of what-is-not—the universe must be homogeneous.

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By these arguments, Parmenides arrives at his picture of the world as a single, undifferentiated, unchanging unity. Needless to say, scholars have disagreed over exactly what he meant. They have questioned whether he meant that the universe was one thing, or only that it was undifferentiated. They have pointed out that since his poem is all about "what-is-not," he could not have been sincere in his assertion that what-is-not is unthinkable. They have wondered whether he was using "is" in a predicative sense—as in, "The cat is black"—or in an existential sense, as in, "The cat is." Some suggest that his conclusions depend on a failure to distinguish these two uses, which weren't clearly separated until Aristotle.

Most damagingly, only half a century after the poem was written down, Anaxagoras pointed out that its central thoughts would, if true, be unthinkable. For if the thoughts have to be thought, they have to come into being. Actual thoughts had by you, me or Parmenides are what philosophers call "occurrents." They take place at a particular time, and are thought by someone who came into being and will pass away at a particular time. An unchanging, undifferentiated universe would not therefore be able to contain the occurrent, differentiated thought that it is itself unchanging and undifferentiated.

While some commentators have suggested that he was simply muddled, Parmenides has attracted a multitude of respectful interpreters. Peter Kingsley has even suggested that his aim was to drive his listeners mad, or to experience death in life. Be that as it may, the afterglow of Parmenides's "moment of absolute, bloodless abstraction," which cast the daylight of the senses into darkness, has transilluminated western thought. We are all, to a greater or lesser degree, his cognitive children.

Some of Parmenides's influence derives from his novel methods. His poem was the first piece of sustained argument in philosophy. He did not merely proclaim the truths he arrived at; he offered, to use Paul Valéry's phase, the "elementary courtesy" of proof. The corollary of this was that he felt that we were bound to accept any conclusion reached by valid argument, however counterintuitive: "Whatever you do, do not be guided by your dull eyes nor by your resounding ears, but test all things with your thinking alone." Plato's contempt for the deliverance of the senses, and, later, Descartes's thought-led systematic doubt, are in the spirit of Parmenides. Parmenides's assertions that what-is is and what-is-not is not were the first statement of the laws of thought, later formalised in Aristotelian and subsequent systems of logic. In On Nature, in other words, we see thought coming to think about itself and setting down its own permissible limits. Parmenides actually asserts that "Thinking and the thought 'it is' are the same." To think of something that is not is, he believes, implicitly to assert simultaneously that it is and that it is not. He is thus plausibly credited with proclaiming the law of contradiction.

His concern with the totality of what-is—with Being as such—was the supreme expression of the pre-Socratic concern with the underlying nature of things as a whole. Parmenides is therefore the first metaphysician, or perhaps more precisely ontologist, through his consideration of, to use Aristotle's phrase, "being qua being." His conclusion that reality is not at all as we experience it, and that it is static, opened the way to the profoundest intuition driving science: that truth can lie outside of direct experience. While scientists ultimately check their beliefs against sense experience, they are willing to countenance a counterintuitive worldview that consigns qualitative experience to the merely subjective. According to science, the world in itself is colourless, soundless, tasteless, odourless. There is nothing bright, coloured or pretty about electromagnetic radiation.

Parmenides's influence is felt throughout philosophy and science in the notion that, as Jonathan Barnes has put it, "the basic stuff of the world has an Eleatic stability." Over the centuries, philosophers have been attracted to the notion of a featureless, unchanging substance underlying everything. While empiricists like David Hume and, later, positivists like Ernst Mach vigorously attacked this idea, it remained dominant until the last century. Even the empiricists buy into the scientific world picture, and it is difficult to escape the impression that they feel that matter is the ultimate reality. Materialism is overwhelmingly the orthodoxy in contemporary philosophy.

Perhaps even more striking is the extent to which this "Eleatic" vision has influenced science. The law of the conservation of matter gradually emerged as a fundamental principle of modern science. When matter proved to be transformable into energy, Eleatic stability was upheld in the notion of the conservation of mass-energy. Most significantly, physics, the most fundamental of all the natural sciences, has had at its heart an increasingly sophisticated account of the world as consisting of indestructible atoms. According to the 5th-century atomists, who argued in direct response to Parmenides, apparent change was simply the reorganisation of ungenerated, imperishable atoms. This "lite" version of the Eleatic vision has, since the late 19th century, taken something of a battering. Atoms seem to be dissolving into energy exchanges and probabilities. Some thinkers have even suggested that Heraclitus—Parmenides's antithesis, who argued that everything was change—is now getting his say. The Parmenidean "obsession with stasis" (to use Mary Midgley's phrase), however, has returned in a dramatic form. Einstein's theories of relativity point to a "block universe" in which change is observer-dependent rather than inherent, and tensed time (past, present and future) is, to echo Einstein, merely an illusion ("but a stubborn one"). More recently, some physicists have questioned the existence not only of tensed time but of time itself. Perhaps more important even than this is the way the Parmenidean vision is ubiquitous in the most distinctive features of science: the equations that assert the essential identity of what exists before and after observed change, and the hunt for invariant laws which express the intuition that surface change expresses unchanging underlying patterns.

No one could sincerely accept, even less live by, Parmenides's conclusions, not only because they are unthinkable, but also because they contain a fundamental error. This is easiest to spot in the assertion in Fragment 3 that "Thinking and the thought 'it is' are the same"; in other words, that it is impossible to think of something that does not exist. This is, of course, incorrect: we are always thinking of things that have no reality outside of our thought. Besides, if thought were confined to what-is, thinking and Being would be one and the same. Without a distance between thought and its objects, so that the thought can exist in the absence of the object, thought would not be about anything. It could not even be about what-is. Consequently there would be no space for truth or falsehood. Parmenides's fundamental error is his failure to allow for the entertaining of explicit possibility. Thought is about what might be the case, rather than what is the case. That, indeed, is why thinking is about "what-is" and "what-is-not," rather than simply being a part of "what-is." Parmenides, in short, overlooks the space of possibility which is the world we collectively create, and in which we live our lives steeped in the presence of the past and the anticipation of the future.

Nevertheless, Parmenides's achievement is extraordinary. In his short poem, thought and knowledge encounter themselves head on for the first time. This is such a huge advance in self-consciousness that it is no exaggeration to call it an "awakening." And notwithstanding the invalidity of his conclusion, there is at the heart of his vision a fundamental truth: that the object of knowledge (captured in a name, a thought, a proposition) is static compared with our experiences. This can be observed even in ordinary perception. When, for example, we see a material object, we see it as the unchanging source of our fluctuating experiences of it. This is more evident when the object is picked out by a name whose meaning must, as Plato emphasised, be stable so that it can do its work of communication. As assertions, thoughts and meanings become more general, so they stand for something that is ever more stable. Parmenides intuited a thought of the utmost generality whose object—Being, the sum total of what-is—would be utterly unchanging. This has shown the way for philosophers and scientists in what we might call the post-Parmenidean era. While Plato, Parmenides's mighty footnote, most explicitly identified reality with unchanging entities—so-called "ideas" or "forms," accessible to the intellect insofar as it was not curdled by sense experience—it is Parmenides's original intuition that has pervaded western thought.

The pre-Socratic revolution in thought that Parmenides brought to its climax is, I believe, a more compelling epistemological break than any that Foucault claimed to discover in post-Renaissance humanism. This raises the question: why did it happen when it did? Why, hundreds of thousands of years after human beings woke to the outside world as an object of knowledge separate from themselves, did they awaken to knowledge itself? What was it that fostered this collision of human consciousness with itself, such that thought came to think about itself and knowledge inquired into its own basis?

The pre-Socratic awakening was the result of a unique concatenation of circumstances in place by the 7th century BC. In his classic investigation The Origin of Greek Thought, published half a century ago, JP Vernant connects the pre-Socratic awakening with the rise of the polis, or city state. Following the end of the Mycenaean empire in the 12th century BC, the Greeks lived in largely agrarian communities for nearly 400 years. With increasing wealth and socioeconomic disparities came a risk of serious disorder. A series of political reorganisations led to the emergence of a participatory democracy, with leaders who were increasingly accountable to the citizens they led. Implicit in this was the assumption that all voices, at least of the minority who had citizenship, were equal. This principle of equality gave persuasion rather than force or authority greater importance as an instrument of governance. It was in this dialogic society, with an emerging ethos of critical discussion, that, in the 7th century BC, Greek philosophy was born in Ionia.

Another driver to the explicitness of thought that made the Parmenidean self-encounter of human consciousness more likely was the rise of cities. Cities make huge cognitive demands of their inhabitants. A city is an "artefactscape," a densely woven network of signs to be interpreted, unexpected events to be handled and an endless procession of strangers to be dealt with. The city was not, of course, invented by the Greeks; but those that emerged in the 8th century BC were quite unlike the palace-based cities of Mycenaean, Minoan and earlier cultures. In the latter, roles were clear and circumscribed, individuals were more immediately legible and there was less casual, unscheduled contact. The earliest city, Catal Huyuk, in what is now Turkey, was, despite its population of several thousand, really a cluster of small, self-sufficient communities of fewer than 50 people who had little contact outside their group. Nothing could be more different from the buzzing, milling organised confusion of the cities of the 8th century onwards.

Evidence from primates about the influence of the size of social groupings on the brain may prove instructive here. The primatologist Robin Dunbar has found a strong correlation between brain size and the size of the cognitive groups—the number of individuals of whom one has social knowledge rather than whom one merely lives with on a daily basis. In early hominids, these groups are of the order of 60 to 80. In a Greek city, the number of people one had to deal with would be enormous and greatly outsize the number of familiars one would be living with.

Another important factor was trade. After the 9th century BC, the Greeks were increasingly driven overseas to trade, particularly for cereals, which were in short supply at home. The trading colonies were largely peaceable, and the colonisers outnumbered by the indigenous peoples. It was as colonisers—like Parmenides in Elea—that the pre-Socratics were born and flourished. Athens did not produce a native-born philosopher of stature until the 5th century BC. Life as this sort of coloniser would have required mastering a certain type of communication. In order to make themselves clear to strangers, who would not have shared their assumptions, background or knowledge, expatriate Greeks would have had to make their thoughts more explicit. This would have had the consequence of making them more aware of themselves—their own thoughts and their own knowledge. They would have become aware of alternative points of view, and of their own distance from the majority viewpoint.

There is one more important driver: writing. This is an extraordinary technology: it stores human consciousness outside of the human body. Even more than speech, it makes consciousness visible and public, therefore exposing it to criticism. As the linguist Roy Harris put it: "Writing… separates pre-literate mankind from true knowledge." Of course, writing long antedated the pre-Socratic awakening. Forms of proto-writing have been observed on bone tools dating back to 9,000 BC. But when literacy returned to Greece some time in the 8th or 7th century BC, it took a radically different form. The Greeks took over the wonderfully flexible alphabet of the Phoenicians and turned it into something more versatile by using spare characters to stand for vowels. All writing in major cultures since has been based upon the Greek alphabet. What is more, when writing returned, it was not subordinated to the needs of a monolithic state, nor was it limited to scribes. Many of the earliest examples of writing in Greece are metrical, their purpose being to entertain rather than inform, and it has been suggested that the invention of the Greek alphabet was prompted by the wish to make a permanent record of oral epic poetry. The unlooked-for consequence of this was thought that thinks about itself. As Catherine Osborne observed, "philosophy was invented at about the time memorable poetic discourse began to give way to written texts." All of these factors prepared the way for the pre-Socratic awakening which established the framework in which subsequent cognitive revolutions have taken place. We may think of what happened as humanity's most decisive step forward into its essential nature as the "explicit animal."

What significance might this have for the present? It is arguable that the revolution in thought started by the Parmenidean vision—belief in an unchanging underlying reality that defies the senses—has run its course. Over the last century, there has been a growing feeling that in crucial areas of knowledge, we have reached an impasse.

For instance, the endeavour to turn the scientific gaze on our own consciousness has run into a brick wall. Although you wouldn't know it from the excitement surrounding brain science, we have made no progress in understanding how it is that we are conscious and are aware of being located in a world that we in part construct and in part encounter as a given. Nor shall we. The Parmenidean dismissal of sense experience, which has licensed the notion that reality is the no-person physical or material world, and that the qualities we perceive in it are merely secondary, has made a neuroscience of consciousness impossible. Dismissing the importance of subjective experiences, or "qualia"—a common ploy among the champions of neurophilosophy such as Daniel Dennett—keeps the impression of progress alive, but this is cheating. Biological science—evolutionary theory and so on—is increasingly assimilating itself to physics, chemistry and mathematics. Gene-eyed evolutionary theory and the rise of molecular biology forge closer connections between the biosphere and what Richard Dawkins has called "the blind forces of physics." Not only does this deepen the tension between an objective understanding of ourselves as organisms and our sense of being conscious agents, it exposes the biological sciences to the difficulties our understanding of the physical world is encountering. At the apex of contemporary physics, we have two mighty theories—quantum mechanics and the general theory of relativity—which are incompatible. The attempt to unite the two theories in "superstring theory" has produced a sterile landscape of 10500 largely untestable theories (although for a new approach, see "Lab report"). Quantum mechanics, as Richard Feynman repeatedly pointed out, is incomprehensible, for all its extraordinary effectiveness. Unresolved issues around the role of the observer—with his "dull eyes" and "resounding ears"—have haunted modern physics: he insinuates himself as a ghost among the atoms even as physics tries to free itself from the past, present and future that matter so much to humans. In considering what was to be accounted as real, Parmenides excluded all that matters to us in our lives, and thus paved the way for a vision of a material world void of meaning. This has brought huge material benefits, but now seems less viable as the foundation of a secular understanding of the world. We no longer seem to know how to proceed in attempting to make better sense of the kinds of beings we are and the universe in which we are situated.

It may be time, therefore, to go back to the time when our cognitive godfather set us on a road to the secular understanding that has been so wonderfully elaborated over the 2,500 years since. We need to return to the Parmenidean moment to see whether, without losing all the gains that post-Parmenidean thought has brought us, there might be another cognitive journey from that which western thought has taken. Precisely because Parmenides was our great beginning, we should try to reimagine his thought and its consequences, in the hope of awakening out of his awakening to one more closely answering to our need for wholeness of understanding.