The Sleep of Reason

by Thomas Nagel

[Published in The New Republic, October 12, 1998, pp. 32-38.]

Fashionable Nonsense: Postmodern Intellectuals' Abuse of Science
by Alan Sokal and Jean Bricmont
(Picador USA, 317 pp., $23.00)


You will remember that in 1996 a physicist at New York University named Alan Sokal brought off a delicious hoax that displayed the fraudulence of certain leading figures in cultural studies. He submitted to the journal Social Text an article entitled "Transgressing the boundaries: Toward a transformative hermeneutics of quantum gravity", espousing the fashionable doctrine that scientific objectivity is a myth, and combining heavy technical references to contemporary physics and mathematics with patently ridiculous claims about their broader philosophical, cultural and political significance, supported by quotations in similar vein from prominent figures like Lacan and Lyotard, and references to many more. The nonsense made of the science was so extreme that only a scientific ignoramus could have missed the joke.

Sokal's article expressed deep admiration for the views of two editors of Social Text, Stanley Aronowitz and Andrew Ross, quoting at length from Aronowitz's crack-brained social interpretations of quantum theory. The article was published in a special issue of Social Text devoted to science studies, Sokal revealed the hoax, and nothing has been quite the same since. We can hope that incompetents who pontificate about science as a social phenomenon without understanding the first thing about its content are on the way out, and that they may some day be as rare as deaf music critics.

This book, published originally in French under the title Impostures Intellectuelles, is a follow-up to the article. Sokal and his coauthor, Jean Bricmont, a physicist at the University of Louvain, decided to produce a fuller discussion of the witless invocations of science and math by intellectuals in other fields. Since the most prominent culprits were French, they first published their book in France, but since the influence of these figures on American literary theory, feminism, and cultural studies is substantial, it is good that it has been translated into English.

Nearly half the book consists of extensive quotations of scientific gibberish from name-brand French intellectuals, together with eerily patient explanations of why it is gibberish. This is amusing at first, but becomes gradually sickening. There is also a long and sensible chapter on skepticism, relativism, and the history and philosophy of science. An introduction and an epilogue discuss the political and cultural significance of the affair. Sokal's hilarious parody, with its 109 footnotes and 219 references, is reprinted here as an appendix, together with comments explaining many of the travesties of science that appear in it.

There are a few differences from the French version. Apart from minor changes, the authors have left out a chapter on Henri Bergson and his misunderstanding of the theory of relativity, thought not to be of sufficient interest to English-speaking readers, and have added an article Sokal published in Dissent about his reasons for producing the parody. (This second article was submitted to Social Text but rejected "on the grounds that it did not meet their intellectual standards" -- an unintended compliment.)

The book is somewhat repetitive: the basic idea is contained in the parody and Sokal's comments on it. But the parody alone is worth the price of the volume:

Postmodern science provides a powerful refutation of the authoritarianism and elitism inherent in traditional science, as well as an empirical basis for a democratic approach to scientific work. For, as Bohr noted, "a comlete elucidation of one and the same object may require diverse points of view which defy a unique description" -- this is quite simply a fact about the world, much as the self-proclaimed empiricists of modernist science might prefer to deny it. In such a situation, how can a self-perpetuating secular priesthood of credentialed "scientists" purport to maintain a monopoly on the production of scientific knowledge? ...

A liberatory science cannot be complete without a profound revision of the canon of mathematics. As yet no such emancipatory mathematics exists, and we can only speculate upon its eventual content. We can see hints of it in the mutidimensional and nonlinear logic of fuzzy systems theory; but this approach is still heavily marked by its origins in the crisis of late-capitalist production relations. Catastrophe theory, with its dialectical emphases on smoothness/discontinuity and metamorphosis/unfolding, will indubitably play a major role in the future mathematics; but much theoretical work remains to be done before this approach can become a concrete tool of progressive political praxis.

The chapters dealing in more detail with individual thinkers reveal that they are beyond parody. Sokal could not create anything as ridiculous as this, from Luce Irigaray:

Is E=Mc2 a sexed equation? Perhaps it is. Let us make the hypothesis that it is insofar as it privileges the speed of light over other speeds that are vitally necessary to us. What seems to me to indicate the possibly sexed nature of the equation is not directly its uses by nuclear weapons, rather it is having privileged what goes the fastest ...
We are offered reams of this stuff, from Jacques Lacan, Julia Kristeva, Bruno Latour, Jean-François Lyotard, Jean Baudrillard, Gilles Deleuze, Régis Debray, and others, together with comments so patient as to be involuntarily comic. In response to Irigaray, for example, Sokal and Bricmont observe:
Whatever one may think about the "other speeds that are vitally necessary to us", the fact remains that the relationship E=Mc2 between energy (E) and mass (M) is experimentally verified to a high degree of precision, and it would obviously not be valid if the speed of light (c) were replaced by another speed.

The writers arraigned by Sokal and Bricmont use technical terms without knowing what they mean, refer to theories and formulas that they do not understand in the slightest, and invoke modern physics and mathematics in support of psychological, sociological, political, and philosophical claims to which they have no relevance. It is not always easy to tell how much is due to invincible stupidity and how much to the desire to cow the audience with fraudulent displays of theoretical sophistication. Lacan and Baudrillard come across as complete charlatans, Irigaray as an idiot, Kristeva and Deleuze as a mixture of the two. But these are delicate judgments.

Of course anyone can be guilty of this kind of thing, but there does seem to be something about the Parisian scene that is particularly hospitable to reckless verbosity. Humanists in France do not have to learn anything about science, yet those who become public intellectuals typically appear on stage in some kind of theoretical armor. It even affects politics. I remember that at a certain point after Iraq's invasion of Kuwait, when the United Nations was working up its response, President Mitterand declared on French television, "Nous sommes dans une logique de guerre."

Mitterand regarded himself as an intellectual, but at least it was fairly clear what he meant by this pretentious formulation. Yet listen to Baudrillard:

In the Euclidean space of history, the shortest path between two points is the straight line, the line of Progress and Democracy. But this is only true of the linear space of the Enlightenment. In our non-Euclidean fin de siècle space, a baleful curvature unfailingly deflects all trajectories. This is doubtless linked to the sphericity of time (visible on the horizon of the end of the century, just as the earth's sphericity is visible on the horizon at the end of the day) or the subtle distortion of the gravitational field.
Sokal and Bricmont emphasize that their criticism is limited to the abuse of science and mathematics and that they are not qualified to evaluate the contributions of these writers to psychology, philosophy, sociology, political theory, and literary criticism. They merely suggest, cautiously, that the dishonesty and incompetence shown in the passages they examine might lead one to approach the writers' other work with a critical eye. Clearly all this name-dropping is intended to bolster their reputations as deep thinkers, and its exposure should arouse skepticism.

Sokal and Bricmont are playing it close to the vest here. They could no doubt find passages in these same works having nothing to do with science that are nonsensical, irresponsible, and indifferent to the meanings of words. Yet there is no direct way to refute a fogbank, and so they have adopted the safer strategy of focusing on the occasions when these writers rashly try to invoke the authority of science and mathematics by using a vocabulary that does have a clear meaning, and which could not serve their purposes, literal or metaphorical, unless it were being used more or less correctly. That also allows them to explain why the scientific material introduced, even if it were not completely garbled, would be irrelevant to the literary, psychological, or social topics being discussed.

I am not sure how many admirers of these writers, or of postmodernist thought generally, will read this book. It is important to follow up on the positive effects of the original hoax, but will teachers of cultural studies and feminist theory go through these patient explanations of total confusion about topology, set theory, complex numbers, relativity, chaos theory, and Gödel's theorem? The scientifically literate will find them amusing up to a point, but for those whose minds have been formed by this material, it may be too late. Or they may claim that these particular writers are not as important as the sales of their books suggest, and that other postmodern theorists don't misappropriate science. Derrida, for example, is absent from the book except for one quote in the original parody, because that was an isolated instance, produced in response to a question at a conference.

Yet the effect of a hatchet job like this, if it succeeds, is not just to undermine the reputations of some minor celebrities; it is also to produce a shift in the climate of opinion, so that insiders with doubts about the intelligibility of all this "theory" are no longer reluctant to voice them, and outsiders who have grumbled privately to one another for years have something concrete to which they can point. Anyone who teaches in an American university has heard similar inanities from students and colleagues in comparative literature or cultural studies. Sokal and Bricmont's book should have an impact at least on the next generation of students.


Although Sokal and Bricmont focus on the abuse and misrepresentation of science by a dozen French intellectuals, and the cognitive relativism of postmodern theory, it broaches a much larger topic -- the uneasy place of science and the understanding of scientific rationality in contemporary culture.

The technological consequences of mathematics, physics, chemistry, and biology permeate our lives, and everyone who has been around for a few decades has witnessed the most spectacular developments. That alone would give science enormous prestige; but it also reinforces the purely intellectual aura of science as a domain of understanding that takes us far beyond common sense, by methods that are often far more reliable than common sense. The problem is that it is not easy for those without scientific training to acquire a decent grasp of this kind of understanding, as opposed to an awareness of its consequences and an ability to parrot some of its terminology. One can be infatuated with the idea of theory without understanding what a theory is.

To have a theory, it is not enough to throw around a set of abstract terms or to classify things under different labels. A theory, whether it is true or false, has to include some general principles by which fresh consequences can be inferred from particular facts -- consequences not already implied by the initial description of those facts. The most familiar theories embody causal principles that enable us to infer from present observation what will happen or what has happened, but there are other kinds of theories -- mathematical, linguistic, or ethical theories, for example -- that describe noncausal systematic relations. A successful theory increases one's cognitive power over its domain, one's power to understand why the particular facts are as they are, and to discover new facts by inference from others that one can observe directly. Most important of all, it provides an understanding of the unifying reality that underlies observed diversity.

You don't have to understand quantum mechanics to appreciate the nature of science. Anyone who has taken introductory chemistry and is familiar with the periodic table of the elements has some idea of how powerful a theory can be -- what an extraordinary wealth of specific consequences can be derived from a limited number of precise but general principles. And understanding classical chemistry requires only a basic spatial imagination and simple mathematics, nothing counterintuitive. But it should be clear that not everything in the world is governed by general principles sufficiently precise and substantive to be embodied in a theory. Theories in the social sciences are possible which depend on principles, even if they are only probabilistic, that apply to large numbers of people; but to employ theoretical-sounding jargon in talking about literature or art has about as much effect as putting on a lab coat, and in most cases the same is true for history.

Unfortunately, the lack of familiarity with real scientific theories sometimes results in imitation of their outward forms together with denigration of their claim to provide a specially powerful source of objective knowledge about the world. This defensive iconoclasm has received crucial support from a radical position in the history and philosophy of science, whose authority is regularly invoked by writers outside those fields: the epistemological relativism or even anarchism found in the writings of Thomas Kuhn and Paul Feyerabend.

As Sokal and Bricmont explain, Kuhn and Feyerabend were writing in the context of an ongoing dispute over the relation of scientific theories to empirical evidence. The logical positivists tried to interpret scientific propositions so that they would be entailed by the evidence of experience. Karl Popper denied that this was possible, but held that scientific propositions, if they were to have empirical content, had to be such that at least their falsehood could be entailed by the evidence of experience. Yet neither of these direct logical relations appears to hold, because the evidentiary relation pro or con between any experience and any theoretical claim always involves auxiliary hypotheses -- things apart from the proposition and the evidence themselves that are being assumed true or false. There is nothing wrong with relying on many assumptions in the ordinary case, but it is always logically possible that some of them may be false, and sometimes that conclusion is forced on us with regard to an assumption that had seemed obvious. When that happens with a truly fundamental aspect of our world view, we speak of a scientific revolution.

So far, none of this implies that scientific reasoning is not objective, or that it cannot yield knowledge of reality. All it means is that a scientific inference from evidence to the truth or falsity of any proposition involves in some degree our whole system of beliefs and experience; and that the method is not logical deduction alone, but a weighing of which elements of the system it is most reasonable to retain and which to abandon when an inconsistency among them appears. In normal inquiry, this is usually easy to determine; but at the cutting edge it is often difficult, and a clear answer may have to await the experimental production of further evidence, or the construction of new theoretical hypotheses.

This means that most of our beliefs at any time must in some degree be regarded as provisional, since they may be replaced when a different balance of reasons is generated by new experience or theoretical ingenuity. It also means that an eternal set of rules of scientific method cannot be laid down in advance. But it does not mean that it cannot be true that a certain theory is the most reasonable to accept given the evidence available at a particular time, and it does not mean that the theory cannot be objectively true, however provisionally we may hold it. Truth is not the same as certainty, or universal acceptance.

Another point sometimes made against the claim of scientific objectivity is that experience is always "theory-laden," as if that meant that any experience which seemed to contradict a theory could be reinterpreted in terms of it, so that nothing could ever rationally require us to accept or reject a theory. But as Sokal and Bricmont point out, nothing of the kind follows.

Suppose I have the theory that a diet of hot fudge sundaes will enable me to lose a pound a day. If I eat only hot fudge sundaes and weigh myself every morning, my interpretation of the numbers on the scale is certainly dependent on a theory of mechanics that explains how the scale will respond when objects of different weights are placed on it. But it is not dependent on my dietary theories. If I concluded from the fact that the numbers keep getting higher that my intake of ice cream must be altering the laws of mechanics in my bathroom, it would be philosophical idiocy to defend the inference by appealing to Quine's dictum that all our statements about the external world face the tribunal of experience as a corporate body, rather than one by one. Certain revisions in response to the evidence are reasonable; others are pathological.

Much of what Kuhn says about great theoretical shifts, and the inertial role of long-established scientific paradigms and their cultural entrenchment in resisting recalcitrant evidence until it becomes overwhelming, is entirely reasonable, but it is also entirely compatible with the conception of science as seeking, and sometimes finding, objective truth about the world. What has made him a relativist hero is the addition of provocative remarks to the effect that Newton and Einstein, or Ptolemy and Galileo, live in "different worlds," that the paradigms of different scientific periods are "incommensurable," and that it is a mistake to think of the progress of science over time as bringing us closer to the truth about how the world really is.

Feyerabend is more consistently outrageous than Kuhn, deriding the privileged position of modern science as a way of understanding the world. "All methodologies have their limitations," he says in Against Method, "and the only `rule' that survives is `anything goes'." As Sokal and Bricmont point out, the first clause of this sentence may be true, but it does not in any way support the second. I was a colleague of Feyerabend's at Berkeley in the 1960s, and once it fell to the two of us to grade the German exam for the graduate students in philosophy. About twenty of them took it, and their papers were numbered to preserve anonymity. We discovered that the department secretary who assigned the numbers had considerately left out the number thirteen, and Feyerabend was appalled and outraged by this display of rank superstition. But his views developed, and both he and Kuhn have a lot to answer for.

Both of them are repeatedly cited in support of the claim that everything, including the physical world, is a social construct existing only from the perspective of this or that cognitive practice, that there is no truth but only conformity or nonconformity to the discourse of this or that community, and that the adoption of scientific theories is to be explained sociologically rather than by the probative weight of reasoning from the experimental evidence. Scientists don't believe this, but many nonscientists now do. For example, Sokal and Bricmont tell us that the sociologist of science Bruno Latour recently challenged as anachronistic the report of French scientists who examined the mummy of Ramses II that the pharaoh had died of tuberculosis, because the tuberculosis bacillus came into existence only when Robert Koch discovered it in 1882.

I do not think this is just a case of malign influence from bad philosophy. The radical relativism found in Kuhn and Feyerabend fell on fertile ground. The postmodernist doctrine that there is nothing outside the text, no world to which it is tied down, seems plausible to the consumers of postmodernist writings because it is so often true of those writings, where language is simply allowed to take off on its own. Those who have no objective standards themselves find it easy to deny them to others.


As Sokal and Bricmont point out, the denial of objective truth on the ground that all systems of belief are determined by social forces is self-refuting if we take it seriously, since it appeals to a sociological or historical claim which would not establish the conclusion unless it were objectively correct. Moreover, it promotes one discipline, such as sociology or history, over the others whose objectivity it purports to debunk, such as physics and mathematics. Given that many propositions in the latter fields are much better established than the theories of social determination by which their objectivity is being challenged, this is like using a ouija board to decide whether your car needs new brake linings.

Relativism is kept alive by a simple fallacy, repeated again and again: the idea that if something is a form of discourse, the only standard it can answer to is conformity to the practices of a linguistic community, and that any evaluation of its content or its justification must somehow be reduced to that. This is to ignore the differences between types of discourse, which can be understood only by studying them from inside. There are certainly domains, such as etiquette or spelling, where what is correct is completely determined by the practices of a particular community. Yet empirical knowledge, including science, is not like this. Where agreement exists, it is produced by evidence and reasoning, and not vice versa. The constantly evolving practices of those engaged in scientific research aim beyond themselves at a correct account of the world, and are not logically guaranteed to achieve it. Their recognition of their own fallibility shows that the resulting claims have objective content.

Sokal and Bricmont argue that the methods of reasoning in the natural sciences are essentially the same as those used in ordinary inquiries like a criminal investigation. In that instance, we are presented with various pieces of evidence, we use lots of assumptions about physical causation, spatial and temporal order, basic human psychology, and the functioning of social institutions, and we try to see how well these fit together with alternative hypotheses about who committed the murder. The data and the background assumptions do not entail an answer, but they often make one answer more reasonable than others. Indeed, they may establish it, as we say, "beyond a reasonable doubt."

That is what scientists strive for, and while reasonable indubitability is not the position of theories at the cutting edge of knowledge, many scientific results achieve it with time through massive and repeated confirmation, together with the disconfirmation of alternatives. Even when the principles of classical chemistry are explained at a deeper level by quantum theory, they remain indispensably in place as part of our understanding of the world.

And yet there is something else about the science produced over the past century that makes it more than a vast extension of the employment of common-sense rationality. The fact is that contemporary scientific theories describing the invisible physical reality underlying the appearances no longer represent a world that can be intuitively grasped, even in rough outline, by the normal human imagination. Newtonian mechanics, the atomic theory of matter, and even the basic principles of electricity and magnetism can be roughly visualized by ordinary people. Quantum theory and the theory of relativity cannot be so visualized, because they introduce concepts of space, time, and the relation between observed and unobserved states of affairs that diverge radically from the intuitive concepts that we all use in thinking about our surroundings.

Scientific progress has accustomed us to the idea that the world has properties very different from those presented to our unaided senses, but classical theories can still be understood through models that are based on what we can see and touch. Everyone understands what it is for something to be composed of parts, and there is no difficulty in extending this idea to parts that are too minute to be seen but are inferable from other evidence, such as that of the chemical reactions between different types of substances. We can perceive the action of gravity and magnetic attraction, and electric currents can be roughly imagined by analogy with the flow of liquids. Yet the world of Einstein's special theory of relativity, in which the interval between two widely separated events cannot be uniquely specified in terms of a spatial distance and a temporal distance, is not one that can be intuitively grasped, even roughly, by a layman.

Our natural idea, an idea entirely suitable for the scale of ordinary experience, that things happen in a unique three-dimensional space and along a unique one-dimensional time order, is so deep a feature of our intuitive conception of the world that it is very hard to make the transition, required by relativity theory, to seeing this as just the way things appear from the point of view of a particular frame of reference. To account for the different spatio-temporal relations that the same events appear to have from different frames of reference in uniform motion relative to one another, it is necessary to postulate a reality of a different kind, relativistic space-time, which can be precisely mathematically described but not really imagined.

Special relativity is not a theory whose interpretation is contested. It reveals an objective reality very different from the way the world appears, but one with clear and definite properties. Quantum theory, by contrast, though it is extremely successful in predicting the observable facts -- deriving from physics the phenomena described by classical chemistry, for example -- seems to present conceptual problems even to the physicists who work with it, problems about how to conceive the underlying reality that the theory describes, which is so different from the observed reality that it explains. If one tries to use ordinary physical imagination to grasp the reality underlying the observations, the result always contradicts the observations. It is impossible to convey the problem without discussing the theory, but one gets a flavor of the difficulty from the usual gloss that in quantum mechanics, we seem forced to think of the basic facts as indeterminate among mutually incompatible observable states -- as if a 50 percent chance of rain, for example, could be the most accurate description of yesterday's weather.

Physics continues to develop, of course, but these two theories have taken us to a conception of the real character of the world that can be grasped only through mathematical formulations and not even roughly by the ordinary imagination. As a result, scientific journalism often reads like mumbo jumbo. Not only does this prevent the assimilation of modern physics into the general educated understanding of the world, it also leads to grotesque misuse of reference to these theories by those who think of them as a kind of magic.

Thus quantum theory, via the Heisenberg indeterminacy principle, and to a lesser extent relativity, are often invoked to show that today even science has had to abandon the idea of an objective, mind-independent reality. But neither theory has this significance, however strange may be the reality that they describe and its interaction with observers. And this alienation will only increase if, as seems likely, science penetrates to less and less intuitively imaginable accounts of the reality that lies behind the familiar manifest world, accounts which rely more and more on mathematics that only specialists can learn.


Sokal and Bricmont are as much concerned with the general rise of irrationalism and relativism as with the abuse of science, and one of their motives is political. Sokal says that what motivated him to produce the parody was a belief that the infestation of the academic left in America with postmodernist relativism badly weakened their position as critics of the established order. To challenge widely accepted practices, it is not enough to say there is no objective truth, and then present an alternative point of view.

Sokal in particular emphasizes that he is an Old Leftist, and that he taught math in Nicaragua during the Sandinista government. Clearly he does not want to be confused with Allan Bloom. As Sokal and Bricmont rightly observe, there is no logical connection between any abstract theory of metaphysics or epistemology and any particular political position. Objectivity with regard to the facts ought to be regarded as essential for any view, left, right, or center, that presents itself as an account of how societies should be organized. Objectivity is implied by every claim that the justification for one system is better than that for another, because justification always involves, in addition to values that may be contested, appeals to the facts that reveal how well a particular system will serve those values. Objectivity should be valued by anyone whose policies are not supported by lies.

The embrace of relativism by many leftist intellectuals in the United States, while it may not be politically very important, is a terrible admission of failure, and an excuse for not answering the claims of their political opponents. The subordination of the intellect to partisan loyalty is found across the political spectrum, but usually it takes the form of a blind insistence on the objective truth of certain supporting facts and refusal to consider evidence to the contrary. So what explains the shift, at least by a certain slice of the intellectual left, to this new form of obfuscation?

Sokal and Bricmont attribute it partly to despair brought on by the course of history:

The communist regimes have collapsed; the social-democratic parties, where they remain in power, apply watered-down neo-liberal policies; and the Third World movements that led their countries to independence have, in most cases, abandoned any attempt at autonomous development. In short, the harshest form of "free market" capitalism seems to have become the implacable reality for the foreseeable future. Never before have the ideals of justice and equality seemed so utopian.
This is a disturbing bit of rhetoric. Anyone whose hopes were dashed by the collapse of communism had either a very feeble grip on reality or a very distasteful set of values, and it is simply playing to the galleries to say that we are now all doomed to the harshest form of free-market capitalism. A return to old-fashioned standards of objectivity of the kind that this book favors would require the abandonment of a lot of left-wing cant, and that is not the same as abandoning the ideals of justice and equality.

Perhaps Sokal and Bricmont are right, and the appeal of relativism comes when one gives up the will to win, and settles for the license to keep saying what one has always said, without fear of contradiction. But I think there is a more direct link between postmodernism and the traditional ideas of the left. The explanation of all ostensibly rational forms of thought in terms of social influences is a generalization of the old Marxist idea of ideology, by which moral principles were all debunked as rationalizations of class interest. The new relativists, with Nietzschean extravagance, have merely extended their exposure of the hollowness of pretensions to objectivity to science and everything else. Like its narrower predecessor, this form of analysis sees "objectivity" as a mask for the exercise of power, and so provides a natural vehicle for the expression of class hatred.

Postmodernism's specifically academic appeal comes from its being another in the sequence of all-purpose "unmasking" strategies that offer a way to criticize the intellectual efforts of others not by engaging with them on the ground, but by diagnosing them from a superior vantage point and charging them with inadequate self-awareness. Logical positivism and Marxism were used by academics in this way, and postmodernist relativism is a natural successor in the role. It may now be on the way out, but I suspect there will continue to be a market in the huge American academy for a quick fix of some kind. If it is not social constructionism, it will be something else -- Darwinian explanations of practically everything, perhaps.

Thomas Nagel's most recent book is The Last Word (Oxford University Press).