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Quantum Philosophy

Quantum Philosophy: Understanding and Interpreting Contemporary Science

Roland Omnès
Translated by Arturo Sangalli
Copyright Date: 1999
Pages: 320
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  • Book Info
    Quantum Philosophy
    Book Description:

    In this magisterial work, Roland Omnès takes us from the academies of ancient Greece to the laboratories of modern science as he seeks to do no less than rebuild the foundations of the philosophy of knowledge. One of the world's leading quantum physicists, Omnès reviews the history and recent development of mathematics, logic, and the physical sciences to show that current work in quantum theory offers new answers to questions that have puzzled philosophers for centuries: Is the world ultimately intelligible? Are all events caused? Do objects have definitive locations? Omnès addresses these profound questions with vigorous arguments and clear, colorful writing, aiming not just to advance scholarship but to enlighten readers with no background in science or philosophy.

    The book opens with an insightful and sweeping account of the main developments in science and the philosophy of knowledge from the pre-Socratic era to the nineteenth century. Omnès then traces the emergence in modern thought of a fracture between our intuitive, commonsense views of the world and the abstract and--for most people--incomprehensible world portrayed by advanced physics, math, and logic. He argues that the fracture appeared because the insights of Einstein and Bohr, the logical advances of Frege, Russell, and Gödel, and the necessary mathematics of infinity of Cantor and Hilbert cannot be fully expressed by words or images only. Quantum mechanics played an important role in this development, as it seemed to undermine intuitive notions of intelligibility, locality, and causality. However, Omnès argues that common sense and quantum mechanics are not as incompatible as many have thought. In fact, he makes the provocative argument that the "consistent-histories" approach to quantum mechanics, developed over the past fifteen years, places common sense (slightly reappraised and circumscribed) on a firm scientific and philosophical footing for the first time. In doing so, it provides what philosophers have sought through the ages: a sure foundation for human knowledge.

    Quantum Philosophy is a profound work of contemporary science and philosophy and an eloquent history of the long struggle to understand the nature of the world and of knowledge itself.

    eISBN: 978-1-4008-2286-7
    Subjects: Physics

Table of Contents

  1. Front Matter
    (pp. i-iv)
  2. Table of Contents
    (pp. v-x)
  3. Preface
    (pp. xi-xii)
  4. Acknowledgments
    (pp. xiii-xiv)
  5. Prelude
    (pp. xv-xxiv)

    We were in hell, or rather in Hades. It is a pleasant place, and I had entered it by chance. Cerberus’ question, “Who are you?,” had first baffled me, but I was lucky to have answered, “A son of Pan’s.” The logic was impeccable: Pan conceived the fauns, who in turn did what it takes to conceive, not only among themselves, and abundantly so. Then, a simple calculation of the odds would confirm that I was descended from them. Cerberus could see that I had not lied, and I came in, without having to drink from the Lethe. And so,...


    • [PART ONE Introduction]
      (pp. 1-5)

      If we must rethink today the links between philosophy and science, it is because we are in the aftermath of a fracture. The most fundamental sciences, those dealing with space, time, and matter, those the Greeks would have called a science of Being, have broken out of the limits of common sense and traditional philosophy. Our objective is to identify, and in a certain sense repair, that void, that breach in the continuity of thought that prevents us from being fully aware of the state, the meaning, and the implications of science. The best way to begin is certainly by...

    • CHAPTER I Classical Logic
      (pp. 6-22)

      Logic is the daughter of Greece, as are democracy, tragedy, rhetoric, history, philosophy, and mathematics. It appears that in most earlier civilizations thoughts were uttered rather than constructed; truth was immediately recognized, not requiring any analysis to impose itself or be accepted. If humans have been thinking for a long time, it was only in a definite place and at a definite time that they began to dissect their own thought mechanisms in order to be able to reason. They were forced to admit that reasoning obeys its own laws, and that it does not give in to the will...

    • CHAPTER II Classical Physics
      (pp. 23-46)

      There was a time when things seemed to be really as we perceive them, and physics was then “classical”—natural, simple, we may also say, or even naive, had it not soon become too rich to fit any of those descriptions. This youth of science will be our next topic, from its origins till near the end of the nineteenth century. Of course, we shall not retrace its entire history, only put out enough landmarks here and there to see how the rise toward formalism gradually imposed itself and, at the same time, consistency settled down. Maxwell’s electrodynamics marked the...

    • CHAPTER III Classical Mathematics
      (pp. 47-61)

      It is unthinkable nowadays that a philosophy of knowledge should dispense with a serious reflection on mathematics. To stop at a meditation on logic, as certain authors do, is unacceptable for a modern science where mathematics, in all its profusion and sophistication, pervades the articulation of concepts and laws.

      The real difficulty, and the reason why many avoid mathematics, consists in giving it its proper place without spending long years of study. Its vastness is truly impressive, and, like the ocean, it contains plenty of delicious foodstuff. Some people, the most vulnerable to its seduction, plunge into it for the...

    • CHAPTER IV Classical Philosophy of Knowledge
      (pp. 62-78)

      What does it mean to understand? How is understanding possible? These questions, which we shall now address, are among the oldest and most important questions in philosophy. Many answers have been proposed, beginning with Plato’s Theaetetus, but they can easily be grouped into two main categories. According to the first one, the world is faithfully represented by our mental images and by ordinary language. For the second category of answers, the world is essentially different from our perception of it. It is in fact the opposition between Aristotle and Plato, which has existed since the origins of philosophy.

      The birth...


    • [PART TWO Introduction]
      (pp. 79-83)

      There is no doubt that we are going through a period of fracture, whose first perceptible manifestations are four centuries old, dating back to the dawn of modern science. But if fracture there is, what is it exactly?

      There are at least two aspects of this fracture whose significance is widely recognized. The first one concerns humankind’s place in the universe and our perception of it, while the second has to do with the pervading consequences of modern technology. The former aspect influences the mind, the latter affects life as a whole.

      Who can ignore today that we are part...

    • CHAPTER V Formal Mathematics
      (pp. 84-107)

      From now on, we shall cease to follow the unfolding of the history of mathematics, which, by the way, is accelerating,¹ and shall rather focus on three ideas we had already come across. The first one concerns the very nature of mathematics, whose purpose is not specifically the study of numbers, geometric figures, or any other particular domain. These are only applications of mathematics and not the essence of it. This essence is the study of the relations that exist among concepts, irrespective of their specific nature. In short, it is the abstract study of form.

      The end of the...

    • CHAPTER VI The Philosophy of Mathematics
      (pp. 108-123)

      We shall now examine the question of the meaning of mathematics. In particular, we shall listen to what philosophers and mathematicians inclined to philosophize think of this science. Whether their answers should be endorsed or rejected remains to be seen, but the present situation will prove sufficiently complex to at least allow us to estimate the stretch of road yet to be traveled.

      What is mathematics, this strange outgrowth of reason, where does it come from, and what is its nature? This question is as old as the subject itself, but it usually attracts only a small number of philosophers...

    • CHAPTER VII Formal Physics
      (pp. 124-146)

      With the works of Maxwell at the end of the nineteenth century, classical physics achieved a profound mutation of its nature. The leading role of the old, visual concepts—position, velocity, force—was coming to an end, mathematics having so far provided them with added precision without altering their original intuitive meaning. That clear vision had now been replaced in part by incomparably more abstract notions, that of an electric or magnetic field, for instance, whose mathematical expression was no longer a simple translation of intuition but the only possible form that was truly explicit. As a consequence, the laws...

    • CHAPTER VIII The Epistemology of Physics
      (pp. 147-158)

      As we have done for mathematics, we must examine the state of the philosophy of physics after this science turned formal. While a philosopher can cope with the technical difficulties of the theory of relativity, the obstacles presented by quantum physics are considerable, which may explain a certain convergence of the views held by physicists and philosophers on its epistemology. In the thirties, the greatest names in physics participated in the debate, and until recently the interested philosopher was reduced to discussing the opinions of Bohr, Einstein, Schrödinger, Heisenberg, Pauli, de Broglie, and a few others.

      I have not tried...


    • [PART THREE Introduction]
      (pp. 159-162)

      We have just appraised the extent of the invasion of science by formalism. It is a disappointing realization, at least at first sight, and it may appear to bode us ill if our aspirations are of a philosophical nature—in other words, if we expect to understand. Who would pretend that his or her understanding is enhanced by surrendering to the language of signs, to a ghastly logic, offering nothing we can see, no source of light? One might be inclined to declare that we have touched the bottom, the incomprehensible, the cold foundations of the world. How could we...

    • CHAPTER IX Between Logic and Physics
      (pp. 163-183)

      Nothing could be more arid than the principles of quantum mechanics. Its concepts and laws are cast in a blunt, inescapable mathematical form, without a trace of anything intuitive, a total absence of the obviousness we see in the things around us. And yet, this theory penetrates reality to a depth our senses cannot take us. Its laws are universal, and they rule over the world of objects so familiar to us. We, who inhabit this world, cannot make our own vision prevail over those arrogant laws, whose concepts seem to flow from an order higher than the one inspired...

    • CHAPTER X Rediscovering Common Sense
      (pp. 184-195)

      Our next task will consist in nothing less than recovering the everyday vision of the world, as it is revealed to us by common sense and visual intuition. We shall start this time from the fundamental laws of nature, which are ultimately of a quantum, and hence formal, character. Since we accept being guided only by logical consistency, our approach will be entirely deductive. It will be based exclusively on the principles of quantum mechanics and, in particular, the logical principle stated at the end of the previous chapter will play a crucial role. What we shall accomplish will not...

    • CHAPTER XI From the Measurable to the Unmeasurable
      (pp. 196-215)

      The reconciliation between common sense and quantum mechanics does not exhaust the lessons we may draw from the latter regarding the theory of knowledge. We have seen how quantum mechanics shut out common sense from the phenomena of the atomic world and this will lead to other revelations. Another major problem looms in the background: the relation between formalism and reality, between theory and nature, which will appear distinctly in the end.

      To deal with the above questions we propose a method that rests solely on the principles of quantum physics, in particular on the logical ones. We shall proceed...

    • CHAPTER XII On Realism
      (pp. 216-234)

      The relation between quantum mechanics and realism has always been a matter of controversy. Much has been written about it by great thinkers. Their shadows over our head should invite us to be cautious, but the topic cannot be ignored in any philosophical analysis.

      The basic question is simple: Is scientific knowledge a knowledge of reality? Realism stands for an affirmative answer. When science explains that a table is made of atoms, how sap ascends in a tree, or the workings of our heart, it is saying, or appears to be saying, what these objects really are. Bernard d’Espagnat carefully...


    • CHAPTER XIII A New Beginning
      (pp. 237-245)

      It has been a long journey, even if we have taken some shortcuts; but it is not over yet, and we have every reason to go still farther. We cannot ignore the signs along the way pointing to the almost immediate presence of a new philosophy of knowledge.

      Let us begin by reviewing the situation. We have started from a state of knowledge familiar to everyone and whose broad lines can be retraced. It is first of all an existential situation where humankind penetrates time and space, and matter too. Humanity is aware of the extent of the universe, it...

    • CHAPTER XIV What Is Science?
      (pp. 246-254)

      In the present chapter we proceed with our review of the state of the question by inquiring into the nature of science.¹

      Every thought rests on some representation. This is how the mind translates our perception of the world. Our memories of it are probably located in the circuits of neural signals that develop under the effect of repeated or violent perceptions, and later become fixed. We perceive a landscape as a whole, vast and still, but at each instant our eye catches only a minute part of it; it is in our memory that we contemplate the picture that...

    • CHAPTER XV Method
      (pp. 255-268)

      We are going to pursue our examination of the state of the question, this time focusing on the method of science. The topic is unavoidable, especially since it is often denied that such a method even exists. I am thinking of course of Feyerabend and his followers. Let us take a look.

      Given the vastness and consistency of today’s science, one cannot help wondering what is the source of those attributes, and even how science itself exists at all. Reality is certainly the cause, but by which powerful method do we question it and obtain such generous and, at times,...

    • CHAPTER XVI Vanishing Perspectives
      (pp. 269-282)

      With respect to what was formerly known, the new elements in the current state of the question may be summarized in three points: logic penetrates the world at the level of matter, and not at the level of our consciousness; our knowledge of the laws of reality is now sufficiently ripe for this consciousness, its intuitive and visual representation, and the common sense it harbors to appear with near-certainty as the consequence of much more general principles; finally, we are ready to accept, pending a complete inventory, that there exists an irreducible disjuncture, a chasm, between theory and reality.


  10. Glossary
    (pp. 283-290)
  11. Name Index
    (pp. 291-294)
  12. Subject Index
    (pp. 295-296)