Introduction and Summary

BOOK I – WHAT DO WE MEAN BY KNOWLEDGE

Introduction

Philosophy is an anti-relativism ─ From the origins of human thought to the current crisis of rationality, the question of truth has been the central problem of philosophy and its regulating idea. From Greek antiquity onwards, philosophy has been built on the fundamental presupposition that the human mind is not only capable of progressively expanding its knowledge of natural phenomena, but also of deepening its understanding of the principles that make this knowledge possible. Sceptical and relativistic objections, although frequently used as a spur to philosophical thought ─ from Socrates ‘I know that I know nothing‘ to Cartesian doubt ─ were not then established as paradigms. Despite the sometimes-heated controversies, the history of thought, up until the Enlightenment, offered a broad picture of a progression of ideas towards greater precision and clarity. While it is true that powers and claims of reason were challenged, sometimes radically, in a number of philosophical disputes, until the turn of the nineteenth century this challenge appeared to be a minority, not to say anecdotal. The nineteenth century, which was the century of many contradictions, beginning with Chateaubriand and ending at the dawn of the brutal outburst of the Great War, was also the century which, in the wake of the theoretical successes of the late eighteenth century, made the practical successes of science visible. The second industrial revolution, which established the new civilisation of rail, iron and then steel, brought profound and lasting changes to Western societies, creating new ways of life and overturning the balance of power. Carried along by the pragmatic ideas of modern science, the spirit of progress blew with such intensity that it ended up undermining the theoretical framework from which it had emerged: the old philosophy was consigned to the archives of history alongside theology and metaphysics, so that philosophers ended up saying, as if to absolve themselves of a burden that had ended up weighing too heavily on their shoulders: « the rest of us have nothing more to do with the idea of truth« . And how, indeed, in the atmosphere of the late nineteenth century, saturated with the fumes of industry and progress, could one survive as a philosopher? Did you have to be so naive as to believe that you could still claim to be searching for the Beautiful, the Good, the True? Didn’t the disillusioned philosopher have to show that he was taking note of the advances in science and immediately renouncing all his old fantasies?

From the middle of the nineteenth century until the 1930s, a large part of philosophy was involved in a movement to align itself with the epistemic model of science. Scientism, positivism, historical materialism, radical materialism, physicalism, structuralism and reductionism were all attempts to bring philosophical reflection into line with the methodological imperatives and validation methods of the sciences. From then on, the philosopher’s claim to unveil the inner workings of things and to grasp their ultimate causes was delegitimised: his task was reduced to analysing the structures, regularities and formal conditions of knowledge, from a perspective in which the quest for a founding principle gave way to the immanent explanation of phenomena. At most, like the scientist, he was left with the possibility of extracting a few islands of truth ─ these second truths that we cautiously call ‘results’. But the primary question, the one that conditions all philosophical endeavour, namely the very possibility of understanding and expressing the world, had itself dissolved, as if struck down by obsolescence. The disappearance of the horizon of truth profoundly transformed the philosopher. What could he expect from a world free of the knife of evidence? Caught between the scientist, the ideologue and the simpleton, and forced to choose between the chronicle of deconstruction and ideological transmutation, the philosopher experienced the inexorable thinning of his field, so that he soon found himself faced with a terrible question for any man who aspires to the search for truth: is philosophy dead

If the question of the death of philosophy was correlated with the inexorable advance the pragmatic spirit that animated modern science, it was also contemporary with an internal debate within philosophy that was largely provoked by the reception of Nietzsche’s work in Europe at the end of the nineteenth and beginning of the twentieth centuries. By putting the old idea of truth on trial[1], Nietzsche’s philosophy was in effect the starting point for a new branch of continental European philosophy which, turning for the most part against the spirit of the Enlightenment and Kant’s philosophy, would end up annexing the problem of truth to the question of values (truth becoming a « value like any other[2]« ). Whereas Nietzsche had been the architect of the dynamiting of the theological roots of philosophy, he paradoxically became the inspirer of a new theology without roots that animated much of twentieth-century Western philosophy. The destruction of the rationalist tradition and the radical questioning of the idea of truth were taken « literally », so to speak, by many of Nietzsche’s successors, who thought of history as written. In short, Nietzsche’s anti-idealistic prophecy had the value of a decree: the thread of the philosophical tradition had been broken, and this had to be acknowledged, but was Nietzsche right in announcing the destruction of the old philosophy of knowledge.

In reality, the question of truth was not settled by Nietzsche or his heirs, firstly because a negative settlement of the question could only be achieved at the price of a logical reversal that Nietzsche always refused to consider ─ the assertion that there is no such thing as truth, if it claims to be valid, contradicts itself insofar as it creates a particular truth while denying the general possibility of truth[3] ─ then because Nietzsche was careful not to confront rational philosophy with the arguments of rationalism, often preferring the accommodating polysemy of the aphorism to the rigour of logical demonstration[4]. This is why we, who are Nietzsche’s successors, are not his trustees (we are not bound by any inheritance). It is therefore up to us to ask ourselves the questions that run through his work, and not to consider them irrevocably settled until we have revisited the difficulties and reassessed the promises. What is a thing? What is being? What can I say about the world? The philosopher is like the child, never completely satisfied with a provisional answer. By endlessly repeating « why? », they seek to get as close as possible to things, to understand their workings and connections. But how precisely can we grasp and say something about the world? How can we find the harmony between our discourse on things and the things themselves? On the survival of this question undoubtedly depends the survival of philosophy and probably also that of science itself.

When the vast majority of modern scientists adopted the materialist point of view as a method and then as a doctrine, thought they had rid themselves of epistemological questions. But it was the emergence of a new anti-materialist paradigm that finally detached science from the fundamental questions it had traditionally set out to answer. It was in October 1927, at the famous Solvay annual congress attended by twenty-nine leading scientists ─ seventeen of whom were or were to become Nobel Prize winners in physics ─ that the major ideological turning point in the epistemology of science in the twentieth century took place. The representatives of the Copenhagen school (Niels Bohr and Werner Heisenberg in particular), advocates of a probabilistic quantum mechanics that made a profound break with the principles of classical physics, opposed the supporters of the deterministic theory to which Albert Einstein, Erwin Schrödinger, Louis de Broglie and Paul Dirac in particular continued to adhere. A long controversy ensued between Niels Bohr and Albert Einstein which, despite the theoretical successes that vindicated Bohr on the non-local nature of quantum mechanics, has still not been definitively resolved. The principle of complementarity that Niels Bohr set out publicly for the first time at the International Congress of Physics held in Como on 16 September 1927 ─ just a few weeks before the Solvay Congress ─ was at the origin of a separation of modern physics into two branches made up, on the one hand, of those who, with Einstein, On the other hand, there were those who, in the wake of Bohr, considered that the theoretical impasses of quantum mechanics could not be overcome within the epistemological framework of classical physics. In the 1920s and 1930s in particular, Nils Bohr’s principle of complementarity was the subject of numerous developments, deepenings and extensions, both from the point of view of understanding science and from the perspective of the philosophy of knowledge that Bohr attempted to sketch out from his initial idea[5]. Nils Bohr originally came up with the idea of complementarity in an attempt to provide an answer to the seemingly insurmountable contradictions raised by the early developments of quantum theory. The apparently dual nature of matter, both wave and particle, and the problem of indeterminacy, whereby it is impossible to know simultaneously the position and the momentum of a single particle ─ which Heisenberg theorised under the name of the « uncertainty principle » ─ plunged physicists into epistemological questions that seemed inextricable. Rather than give in to the idea, defended in particular by Einstein, that quantum mechanics did not offer a complete description of reality, Nils Bohr argued that there had to be several necessary descriptions of the same phenomenon, that pairs of mutually exclusive descriptions could be applied simultaneously, without any of the isolated descriptions being sufficient to give an exhaustive description of the phenomenon in question (an exhaustive description in the classical sense being, therefore, impossible). The idea of complementarity was a response to this threefold observation: the quantum description of a phenomenon, although contradictory to the classical description, was in fact « irreducibly » complementary to it. The quantum description of the phenomenon was no longer in direct contradiction with classical physics, and the change of scale justified the paradigm shift. In Bohr’s approach, however, we must not overlook the significance of the problem of indeterminacy, which is itself closely linked to the more fundamental problem of measurement. Whereas, in classical physics, the question of measurement remained secondary, on the atomic scale it became of decisive importance. Since the measurement of any phenomenon can only be envisaged in terms of its interaction with that phenomenon, it was only to be expected that the observer would have to play a gradually disruptive role as he approached the atomic scale. Whereas in classical physics the experimenter was always dealing with the measurement of an organised system, on the quantum mechanical scale the physicist was confronted with the individuality[6] of atomic phenomena, an individuality inevitably disturbed by the duality introduced by the very idea of measurement. It was therefore necessary to give up the Sirius point of view that the classical physicist thought he could have on things and to integrate the observer (the measuring instrument) into the very heart of quantum theory. In short, on the scale of atomic observation, the old philosophical problem of the separation between subject and object, and the question of their respective delimitation in the definition and description of phenomena, reappeared. At the atomic level, however, the separation was no longer a problem for theorists but called into question the very idea of experiment and experimentation. Bohr’s solution was to reconcile two irreconcilable descriptions of reality in a modular and pragmatic approach to physical phenomena: at the level of organised systems of particles, classical epistemological principles continued to apply, whereas the description of quantum phenomena could rightly claim ─ in the name of complementarity ─ to be free from the space-time principles and causality that dominated classical physics (causality that the observer could no longer observe himself, his position as a disrupter condemning him to become the decoder-interpreter of his own experiments[7]).

Although Bohr continued to reflect on the relationship between classical epistemology and quantum physics for most of his life, it was mainly the pragmatic dimension of his approach that was adopted by the followers of the Copenhagen school. Following Bohr’s remarks, scientists generally ended up turning away from epistemological questions and devoting themselves to developing descriptive theoretical models whose ambition was no longer to explain reality in the terms of classical physics[8]. From the 1940s onwards, quantum mechanics was increasingly seen as a theoretical formalism and less and less as an attempt to provide a rational explanation of phenomena. « If you think you understand quantum mechanics, you don’t understand it », the physicist Richard Feynman, who was awarded the Nobel Prize for Physics in 1965, used to say in his university lectures: the modern theories of quantum physics were not intended to explain the world, but simply to make it work. The major difficulties caused by the unresolved contradictions between the theory of general relativity developed by Einstein ─ valid at the level of large ensembles, but inoperative at the atomic and subatomic levels ─ still bear witness to the epistemological rifts that opened up in the 1920s and never really closed. Modern science, no doubt carried away by the flow of its practical-theoretical development, increasingly neglected the study of its epistemological foundations: materialism itself had ended up in the epistemological dead ends of quantum indeterminism.

While many physicists were careful not to take a position on the question of the general coherence of quantum mechanics and its completeness ─ the majority leaning towards the completeness hypothesis ─ this was not entirely the case with biologists and neuroscientists, most of whom remained committed to the classical ideas of materialism (ideas that remained valid on their own scale). Here too, however, the problem of complementarity arose, albeit in very different terms. Already in the 1930s, Nils Bohr, reviving the positions taken by his father Christian Bohr, professor of physiology at the University of Copenhagen, saw in the debate between mechanism and finalism[9] a possible extension of his principle of complementarity. In Bohr’s view, mechanism and finalism, fruitful though mutually exclusive scientific theories, could be seen as complementary. In biology, as in psychology, Bohr insisted on the limits of the purely mechanistic approach which, in attempting to reduce psychic or physical processes to the individuality of isolated particles, overlooked the individuality and integrity of the whole organism. In an interview he gave on 17 November 1962[10], shortly before his death, Bohr revealed that the application of the principle of complementarity to psychology had been inspired by his reading, around 1905, of The Principles of Psychology by the pragmatist William James, in which James showed that it is impossible to break down consciousness into its component parts [11]. In the contemporary debate within the neurosciences, this problem of complementarity ─ or, at any rate, of the juxtaposition of two fertile positions that seem mutually irreconcilable ─arose again through the questions linked to the emergence of consciousness: how, in short, can a mass of matter think, feel, speak… and claim to say something about the world? Neuroscientists assure us that this problem of emergence will soon be solved, so that materialism can find its ultimate justification in developments in the life sciences. But can we be sure of this? By promising us a solution in the near future to a problem that is thousands of years old[12], will neuroscientists not also believe ─ as philosophers once did ─ in the possibility of leaping over their own shadow? Will they not find, at the end of the road, the great questions that have driven philosophy since the origins of thought? And what will happen when, after so much wandering and trial and error, they think they have found that ultimate, foundational ‘truth’ whose possibility they began by denying[13]?

For man, the question of truth is neither a technical issue nor an appendix to philosophy. In fact, it goes far beyond the issue of the future of philosophy: it determines the way we relate to the world, the way we understand it and the way we act in it. It is a compass, a thread of Ariadne, for every man who asks questions about things, a thread that he strives to feel and follow through the specious twists and turns of ideologies, integral relativism, anti-rationalism and anti-science. Throughout the twentieth century, the century of modern wars, general violence and suspicion, the idea gradually took hold that the compass had been lost, that the thread had broken. We had to admit that « all points of view are equal », and that truth was a chimera. « Let’s leave it at that », declared Jean-Luc Nancy in a lecture he gave at the Zurich University of Applied Sciences in 1980[14]. The credo of the twentieth century was that we should no longer bother ourselves with a question that belonged to the past, and that we should dig the bewitching furrow of irrationalism. It was thought at the time that the disaffection with the question of truth was the result of a long and irreversible evolutionary process, and that the entire history of philosophy tended towards this conclusion. Nothing could be further from the truth. Distrust of the idea of truth is not the result of a linear progression in the history of ideas. Doubt, struggle and confrontation have always existed and marked the cleavages in the history of thought. Plato against the Sophists, the Humanists against Scholasticism, the Enlightenment against the Anti-Enlightenment… Throughout history, ideas have always given rise to their own contradictions. In the field of thought, as elsewhere, we must be wary of the myth of linear progress.

Preliminary note

In this book, I endeavour to show that the question of truth has not been definitively settled by the advent of modern science and materialist methodology ─ of which Darwinism was one of the manifestations and one of the resounding successes ─ that it cannot have been, and that it remains a central issue. It seems to me, however, that the proposition of putting the question of truth back on the table can only be admissible under certain conditions. First of all, I believe that any philosopher who claims to be doing serious work on the question of truth and the foundations of knowledge must not only have a good knowledge of the history of philosophy, but also, and perhaps above all, must have taken a close interest in the great scientific revolutions of the modern era, and especially in those that have revolutionised the twentieth century: the theory of relativity and quantum mechanics (which does not exclude the more recent discoveries and theories that are often linked to or derived from them). Of course, I don’t claim to have covered all these issues (who could?), but at least I feel that I have grasped their main methodological and epistemological foundations. So, I have tried to provide some answers, or at least some contradiction. Secondly, it seemed to me that a ‘new’ form should be sought. Thus, I opted for a ‘schematic’ and ‘visual’ presentation of my ideas rather than a work that would have placed greater emphasis on logical argumentative sequences (although these sequences remain in the present work). I have favoured short paragraphs and aphorisms where I felt this was appropriate, and tried to put my thoughts into images where I felt this was relevant. This form seems to me to be in keeping with the basic idea that I want to defend here: truth is always conceived in the mode of harmony, agreement, correspondence and parallelism, and the deductive method of logic is merely a means of ‘showing’ it. Truth, as I shall try to show, is not grasped solely by the dryness of rational argument but manifests itself through several modes of relation to the object (visual, auditory, imaginative, sentimental…). Moreover, it seems to me that an overly mechanistic conception of reason has been the source of many misunderstandings throughout the history of philosophy. The form I am proposing here also argues, by way of parallelism, for a broadening of rationalism. I don’t always intend to win people over with an argument that seeks to persuade, but rather to explain, to show, to make them feel where possible, without giving in to the facilities of didacticism. Finally, it seemed to me that the criticisms of materialism, including the most recent materialism (I’m thinking in particular of physicalism) which radicalises the positions of classical materialism with regard to the idea of truth, should be taken seriously. This is why the beginning of this book was conceived as a response to materialists, and in particular to physicalists and neo-Darwinists. The two fundamental criticisms that sceptical materialism makes of classical philosophy are, in my view, the following: firstly, there is nothing to indicate that there is anything other than matter, forces and particles that organise and structure reality. The idea of individuality therefore needs to be rethought in the light of the fact that the individual is merely an organisational unit made up of matter. Consequently, what we call will, freedom, ideas and truth are in turn nothing more than particular manifestations of an organisation of matter, this organisation being the result of a long evolutionary process governed by chance. Thus, where we think we see ‘truths’, there are in reality only chemical and mental processes which, through an exchange of matter, give us the illusion of absolute agreement, when in fact there are only chain reactions which mean nothing in and of themselves (circularity argument). The corollary of this argument is the idea that, secondly, man cannot claim to transcend the matter of which he is made (argument from finitude), insofar as, like any organism, animate or inanimate, he is totally reduced to it and cannot extricate himself from it to adopt a position of superiority. As Protagoras asserted more than two thousand years ago, it is itself the standard of what it claims to measure: « the measure of all things ». While these criticisms are not entirely new in substance, they have the advantage of being radical (which sometimes brings a form of clarity). So, it seemed to me essential to consider them in all their depth and in all their implications. In a universe where there is nothing to indicate that it is not made up entirely of finite matter, how can we claim to be free from the circularity of our reasoning, our desires and our feelings? How can we even attach any meaning to the idea of truth and all the other ideas produced by our reason? If man is the measure of all things, then in order to answer these questions we must undoubtedly go back to the unit of organised matter we call man. In this attempt to return to the human being, we will look at what, since the origins of humanity, has perhaps been one of the keys to understanding man, as well as a fundamental question for philosophy and science: music. Although it may seem surprising to link the fate of truth to that of music, it was through music that the question of truth first came to mind. At first glance, music does not seem to be the most obvious route to the question of truth: it is non-figurative, designates or signifies nothing, corresponds to nothing and seems intimately linked to subjectivity, feeling and imagination. So, there is nothing here that would dispose me to pose the question of truth in a new way, all the more so since it was not my intention to recycle the old Nietzschean idea of aesthetic truth, freed from the concept of adequacy. Yet the study of music, of its mechanisms, without being reduced to the study of the physical laws that drive the universe, is similar in many respects. Although it does not possess the explanatory power of physical law, music exposes a raw logical reality, that of the numerical essence of the world, at the same time as it refers us, without being totally reduced to it, to our own subjectivity, to what makes us react, think, feel ─ in short, that we are human beings.

[1] On this subject, see Éric Blondel, Les guillemets de Nietzsche : philologie et généalogie in Nietzsche aujourd’hui ?

[2] See Geoffroy de Clisson, Les Anti-humanistes ou l’avènement des Contre-Lumières.

[3] What are we to make of Nietzsche’s assertion that « there is no truth »? Either it is true and contradicts itself, since there is at least one true assertion (the one asserting that there is no truth), or it is false and truth exists.

[4] « What needs to be demonstrated in order to be believed is not worth much », wrote Nietzsche in Twilight of the Idols.

[5] See Bernadette Bensaude-Vincent, L’évolution du principe de complémentarité dans les textes de Bohr (1927-1939), in Revue d’histoire des sciences, 1985, pp. 231-250.

[6] A notion that Bohr himself put forward in explaining his principle of complementarity.

[7] The closer the physicist gets to the quantum scale, the more the results are deduced rather than observed. This deductive and interpretative approach becomes inevitable at the particle scale.

[8] In this they probably betrayed the ambition of Nils Bohr, who wrote in 1949: » The new progress in atomic physics was commented upon from various sides at the International Physical Congress held in September 1927, at Como in commemoration of Volta. In a lecture on that occasion, I advocated a point of view conveniently termed « complementarity, » suited to embrace the characteristic features of individuality of quantum phenomena, and at the same time to clarify the peculiar aspects of the observational problem in this field of experience. For this purpose, it is decisive to recognise that, however far the phenomena transcend the scope of classical physical explanation, the account of all evidence must be expressed in classical terms. The argument is simply that by the word « experiment » we refer to a situation where we can tell others what we have done and what we have learned and that, therefore, the account of the experimental arrangement and of the results of the observations must be expressed in unambiguous language with suitable application of the terminology of classical physics. in Discussions with Einstein on Epistemological Problems in Atomic Physics.

[9] In biology, mechanism and finalism are two opposing explanatory frameworks. Mechanism considers that biological phenomena result solely from material and efficient causes, without intention or purpose. It is part of a physico-chemical approach in which organisms are analysed as systems governed by blind causal interactions (e.g. natural selection explains evolution without any underlying intention). Finalism, on the other hand, postulates that biological structures and functions tend towards an intrinsic finality, as if they were oriented towards a goal (e.g. the eye seems designed to see). In modern biology, finalism is generally rejected as a causal explanation, but certain concepts, such as teleonomy, make it possible to talk about apparent finality without resorting to an intentional principle.

[10] On 17 November 1962, shortly before his death, Niels Bohr gave an interview to Thomas S. Kuhn, Leon Rosenfeld, Aage Petersen and Erik Rudinger. This discussion was part of a series of interviews conducted between 31 October and 17 November 1962, as part of the Archives for the History of Quantum Physics. These interviews took place in Bohr’s office at Carlsberg, Copenhagen, Denmark.

[11] The Principles of Psychology, « The stream of thougts », William James, 1896, quoted by Bernadette Bensaude-Vincent, L’évolution du principe de complémentarité dans les textes de Bohr (1927-1939), in Revue d’histoire des sciences, 1985, p. 248.

[12] See in particular Stanislas Dehaene, Consciousness and the Brain: Deciphering How the Brain Codes Our Thoughts

[13] The idea of materialism (a monistic system) by definition denies the idea of an absolute truth, as we shall see later.

[14] Jean-Luc Nancy, Notre Probité in L’Impératif catégorique, lecture given in January 1980 at the Philosophische Fakultät in Zurich: « We know that it is easy to try to ‘nail’ Nietzsche, who would only speak in the name of one more adequate truth, or rather of the always identical adequate truth.

We also know, as Heidegger has shown, that anyone who thinks he is telling the truth about Nietzsche in this way – in order to denounce him – is himself claiming the truth of his discourse on Nietzsche. Now, if he wants to take Nietzsche to task in the name of the proposition that truth is illusion, he in falls under the accusation, etc. So let’s leave it at that.