People have been talking bull, denying that they were talking bull, and accusing others of talking bull for ages. �Dumbe Speaker! that's a Bull,� a character in a seventeenth-century English play says. �It is no Bull, to speak of a common Peace, in the place of War,� a statesman from the same era declares. The word �bull,� used to characterize discourse, is of uncertain origin. One venerable conjecture was that it began as a contemptuous reference to papal edicts known as bulls (from the bulla, or seal, appended to the document). Another linked it to the famously nonsensical Obadiah Bull, an Irish lawyer in London during the reign of Henry VII. It was only in the twentieth century that the use of �bull� to mean pretentious, deceitful, jejune language became semantically attached to the male of the bovine species�or, more particularly, to the excrement therefrom. Today, it is generally, albeit erroneously, thought to have arisen as a euphemistic shortening of �bullshit,� a term that came into currency, dictionaries tell us, around 1915.

If �bullshit,� as opposed to �bull,� is a distinctively modern linguistic innovation, that could have something to do with other distinctively modern things, like advertising, public relations, political propaganda, and schools of education. �One of the most salient features of our culture is that there is so much bullshit,� Harry G. Frankfurt, a distinguished moral philosopher who is professor emeritus at Princeton, says. The ubiquity of bullshit, he notes, is something that we have come to take for granted. Most of us are pretty confident of our ability to detect it, so we may not regard it as being all that harmful. We tend to take a more benign view of someone caught bullshitting than of someone caught lying. (�Never tell a lie when you can bullshit your way through,� a father counsels his son in an Eric Ambler novel.) All of this worries Frankfurt. We cannot really know the effect that bullshit has on us, he thinks, until we have a clearer understanding of what it is. That is why we need a theory of bullshit.

Frankfurt's own effort along these lines was contained in a paper that he presented two decades ago at a faculty seminar at Yale. Later, that paper appeared in a journal, and then in a collection of Frankfurt's writings; all the while, photocopies of it passed from fan to fan. Earlier this year, it was published as �On Bullshit� (Princeton; $9.95), a tiny book of sixty-seven spaciously printed pages that has gone on to become an improbable best-seller.

Philosophers have a vocational bent for trying to divine the essences of things that most people never suspected had an essence, and bullshit is a case in point. Could there really be some property that all instances of bullshit possess and all non-instances lack? The question might sound ludicrous, but it is, at least in form, no different from one that philosophers ask about truth. Among the most divisive issues in philosophy today is whether there is anything important to be said about the essential nature of truth. Bullshit, by contrast, might seem to be a mere bagatelle. Yet there are parallels between the two which lead to the same perplexities.

Where do you start if you are an academic philosopher in search of the quiddity of bullshit? �So far as I am aware,� Frankfurt dryly observes, �very little work has been done on this subject.� He did find an earlier philosopher's attempt to analyze a similar concept under a more genteel name: humbug. Humbug, that philosopher decided, was a pretentious bit of misrepresentation that fell short of lying. (A politician talking about the importance of his religious faith comes to mind.) Frankfurt was not entirely happy with this definition. The difference between lies and bullshit, it seemed to him, was more than a matter of degree. To push the analysis in a new direction, he considers a rather peculiar anecdote about the philosopher Ludwig Wittgenstein. It was the nineteen-thirties, and Wittgenstein had gone to the hospital to visit a friend whose tonsils had just been taken out. She croaked to Wittgenstein, �I feel just like a dog that has been run over.� Wittgenstein (the friend recalled) was disgusted to hear her say this. �You don't know what a dog that has been run over feels like,� he snapped. Of course, Wittgenstein might simply have been joking. But Frankfurt suspects that his severity was real, not feigned. This was, after all, a man who devoted his life to combatting what he considered to be pernicious forms of nonsense. What Wittgenstein found offensive in his friend's simile, Frankfurt guesses, was its mindlessness: �Her fault is not that she fails to get things right, but that she is not even trying.�

The essence of bullshit, Frankfurt decides, is that it is produced without any concern for the truth. Bullshit needn't be false: �The bullshitter is faking things. But this does not mean that he necessarily gets them wrong.� The bullshitter's fakery consists not in misrepresenting a state of affairs but in concealing his own indifference to the truth of what he says. The liar, by contrast, is concerned with the truth, in a perverse sort of fashion: he wants to lead us away from it. As Frankfurt sees it, the liar and the truthteller are playing on opposite sides of the same game, a game defined by the authority of truth. The bullshitter opts out of this game altogether. Unlike the liar and the truthteller, he is not guided in what he says by his beliefs about the way things are. And that, Frankfurt says, is what makes bullshit so dangerous: it unfits a person for telling the truth.

Frankfurt's account of bullshit is doubly remarkable. Not only does he define it in a novel way that distinguishes it from lying; he also uses this definition to establish a powerful claim: �Bullshit is a greater enemy of truth than lies are.� If this is true, we ought to be tougher on someone caught bullshitting than we are on someone caught lying. Unlike the bullshitter, the liar at least cares about the truth. But isn't this account a little too flattering to the liar? In theory, of course, there could be liars who are motivated by sheer love of deception. This type was identified by St. Augustine in his treatise �On Lying.� Someone who tells a lie as a means to some other goal tells it �unwillingly,� Augustine says. The pure liar, by contrast, �takes delight in lying, rejoicing in the falsehood itself.� But such liars are exceedingly rare, as Frankfurt concedes. Not even Iago had that purity of heart. Ordinary tellers of lies simply aren't principled adversaries of the truth. Suppose an unscrupulous used-car salesman is showing you a car. He tells you that it was owned by a little old lady who drove it only on Sundays. The engine's in great shape, he says, and it runs beautifully. Now, if he knows all this to be false, he's a liar. But is his goal to get you to believe the opposite of the truth? No, it's to get you to buy the car. If the things he was saying happened to be true, he'd still say them. He'd say them even if he had no idea who the car's previous owner was or what condition the engine was in.

Frankfurt would say that this used-car salesman is a liar only by accident. Even if he happens to know the truth, he decides what he's going to say without caring what it is. But then surely almost every liar is, at heart, a bullshitter. Both the liar and the bullshitter typically have a goal. It may be to sell a product, to get votes, to keep a spouse from walking out of a marriage in the wake of embarrassing revelations, to make someone feel good about himself, to mislead Nazis who are looking for Jews. The alliance the liar strikes with untruth is one of convenience, to be abandoned the moment it ceases to serve this goal.

The porousness of Frankfurt's theoretical boundary between lies and bullshit is apparent in Laura Penny's �Your Call Is Important to Us: The Truth About Bullshit� (Crown; $21.95). The author, a young Canadian college teacher and former union organizer, begins by saluting Frankfurt's �subtle and useful� distinction: �The liar still cares about the truth. The bullshitter is unburdened by such concerns.� She then proceeds to apply the term �bullshit� to every kind of trickery by which powerful, moneyed interests attempt to gull the public. �Most of what passes for news,� Penny submits, �is bullshit�; so is the language employed by lawyers and insurance men; so is the use of rock songs in ads. She even stretches the rubric to apply to things as well as to words: �The new product that will change your life is probably just more cheap, plastic bullshit,� she writes. At times, despite her nod to Frankfurt, Penny appears to equate bullshit with deliberate deceit: �Never in the history of mankind have so many people uttered statements they know to be untrue.� But then she says that George W. Bush (�a world-historical bullshitter�) and his circle �distinguish themselves by believing their own bullshit,� which suggests that they themselves are deluded.

Frankfurt concedes that in popular usage �bullshit� is employed as a �generic term of abuse, with no very specific literal meaning.� What he wanted to do, he says, was to get to the essence of the thing in question. But does bullshit have a single essence? In a paper published a few years ago, �Deeper Into Bullshit,� G. A. Cohen, a fellow of All Souls College, Oxford, protested that Frankfurt excludes an entire category of bullshit: the kind that appears in academic works. If the bullshit of ordinary life arises from indifference to truth, Cohen says, the bullshit of the academy arises from indifference to meaning. It may be perfectly sincere, but it is nevertheless nonsensical. Cohen, a specialist in Marxism, complains of having been grossly victimized by this kind of bullshit as a young man back in the nineteen-sixties, when he did a lot of reading in the French school of Marxism inspired by Louis Althusser. So traumatized was he by his struggle to make some sense of these defiantly obscure texts that he went on to found, at the end of the nineteen-seventies, a Marxist discussion group that took as its motto Marxismus sine stercore tauri��Marxism without the shit of the bull.�

Anyone familiar with the varieties of �theory� that have made their way from the Left Bank of Paris into American English departments will be able to multiply examples of the higher bullshit ad libitum. A few years ago, the physicist Alan Sokal concocted a deliberately meaningless parody under the title �Transgressing the Boundaries: Toward a Transformative Hermeneutics of Quantum Gravity,� and then got it accepted as a serious contribution to the journal Social Text. It would, of course, be hasty to dismiss all unclear discourse as bullshit. Cohen adduces a more precise criterion: the discourse must be not only unclear but unclarifiable. That is, bullshit is the obscure that cannot be rendered unobscure. How would one defend philosophers like Hegel or Heidegger from the charge that their writings are bullshit? Not, Cohen says, by showing that they cared about the truth (which would be enough to get them off the hook if they were charged with being bullshitters under Frankfurt's definition). Rather, one would try to show that their writings actually made some sense. And how could one prove the opposite: that a given statement is hopelessly unclear, and hence bullshit? One proposed test is to add a �not� to the statement and see if that makes any difference to its plausibility. If it doesn't, that statement is bullshit. As it happens, Heidegger once came very close to doing this himself. In the fourth edition of his treatise �What Is Metaphysics?� (1943), he asserted, �Being can indeed be without beings.� In the fifth edition (1949), this sentence became �Being never is without beings.�

Frankfurt acknowledges the higher bullshit as a distinctive variety, but he doesn't think it's very dangerous compared with the sort of bullshit that he is concerned about. While genuinely meaningless discourse may be �infuriating,� he says, it is unlikely to be taken seriously for long, even in the academic world. The sort of bullshit that involves indifference to veracity is far more insidious, Frankfurt claims, since the �conduct of civilized life, and the vitality of the institutions that are indispensable to it, depend very fundamentally on respect for the distinction between the true and the false.�

How evil is the bullshitter? That depends on how valuable truthfulness is. When Frankfurt observes that truthfulness is crucial in maintaining the sense of trust on which social co�peration depends, he's appealing to truth's instrumental value. Whether it has any value in itself, however, is a separate question. To take an analogy, suppose a well-functioning society depends on the belief in God, whether or not God actually exists. Someone of subversive inclinations might question the existence of God without worrying too much about the effect that might have on public morals. And the same attitude is possible toward truth. As the philosopher Bernard Williams observed in a book published in 2002, not long before his death, a suspicion of truth has been a prominent current in modern thought. It was something that Williams found lamentable. �If you do not really believe in the existence of truth,� he asked, �what is the passion for truthfulness a passion for?�

The idea of questioning the existence of truth might seem bizarre. No sane person doubts that the distinction between true and false is sharp enough when it comes to statements like �Saddam had W.M.D.s� or �The cat is on the mat.� But when it comes to more interesting propositions-assertions of right and wrong, judgments of beauty, grand historical narratives, talk about possibilities, scientific statements about unobservable entities�the objectivity of truth becomes harder to defend. �Deniers� of truth (as Williams called them) insist that each of us is trapped in his own point of view; we make up stories about the world and, in an exercise of power, try to impose them on others.

The battle lines between deniers and defenders of absolute truth are strangely drawn. On the pro-truth side, one finds Pope Benedict XVI, who knows that moral truths correspond to divine commands and rails against what he calls the �dictatorship of relativism.� On the �anything goes� side, one finds the member of the Bush Administration who mocked the idea of objective evidence by declaring, �We're an empire now, and when we act, we create our own reality.� Among philosophers, Continental poststructuralists like Bruno Latour, Jean Baudrillard, and the late Jacques Derrida tend to be arrayed on the anti-truth side. One might expect their hardheaded counterparts in Britain and the United States�practitioners of what is called analytical philosophy�to be firmly in the pro-truth camp. And yet, as Simon Blackburn observes in �Truth: A Guide� (Oxford; $25), the �brand-name� Anglophone philosophers of the past fifty years�Wittgenstein, W. V. Quine, Thomas Kuhn, Donald Davidson, Richard Rorty�have developed powerful arguments that seem to undermine the commonsense notion of truth as agreement with reality. Indeed, Blackburn says, �almost all the trends in the last generation of serious philosophy lent aid and comfort to the 'anything goes' climate��the very climate that, Harry Frankfurt argued, has encouraged the proliferation of bullshit.

Blackburn, who is himself a professor of philosophy at Cambridge University, wants to rally the pro-truth forces. But he is also concerned to give the other side its due. In �Truth,� he scrupulously considers the many forms that the case against truth has taken, going back as far as the ancient Greek philosopher Protagoras, whose famous saying �Man is the measure of all things� was seized upon by Socrates as an expression of dangerous relativism. In its simplest form, relativism is easy to refute. Take the version of it that Richard Rorty, a philosopher who teaches at Stanford, once lightheartedly offered: �Truth is what your contemporaries let you get away with.� The problem is that contemporary Americans and Europeans won't let you get away with that characterization of truth; so, by its own standard, it cannot be true. (The late Sidney Morgenbesser's gripe about pragmatism�which, broadly speaking, equates truth with usefulness�was in the same spirit: �The trouble with pragmatism is that it's completely useless.�) Then, there is the often heard complaint that the whole truth will always elude us. Fair enough, Blackburn says, but partial truths can still be perfectly objective. He quotes Clemenceau's riposte to skeptics who asked what future historians would say about the First World War: �They will not say that Belgium invaded Germany.�

If relativism needed a bumper-sticker slogan, it would be Nietzsche's dictum �There are no facts, only interpretations.� Nietzsche was inclined to write as if truth were manufactured rather than discovered, a matter of manipulating others into sharing our beliefs rather than getting those beliefs to �agree with reality.� In another of his formulations, �Truths are illusions that we have forgotten are illusions.� If that's the case, then it is hard to regard the bullshitter, who does not care about truth, as all that villainous. Perhaps, to paraphrase Nietzsche, truth is merely bullshit that has lost its stench. Blackburn has ambivalent feelings about Nietzsche, who, were it not for his �extraordinary acuteness,� would qualify as �the pub bore of philosophy.� Yet, he observes, at the moment Nietzsche is the most influential of the great philosophers, not to mention the �patron saint of postmodernism,� so he must be grappled with. One of Nietzsche's more notorious doctrines is perspectivism-the idea that we are condemned to see the world from a partial and distorted perspective, one defined by our interests and values. Whether this doctrine led Nietzsche to a denial of truth is debatable: in his mature writings, at least, his scorn is directed at the idea of metaphysical truth, not at the scientific and historical varieties. Nevertheless, Blackburn accuses Nietzsche of sloppy thinking. There is no reason, he says, to assume that we are forever trapped in a single perspective, or that different perspectives cannot be ranked according to accuracy. And, if we can move from one perspective to another, what is to prevent us from conjoining our partial views into a reasonably objective picture of the world?

Today, Richard Rorty is probably the most prominent �truth-denier� in the academy. What makes him so formidable is the clarity and eloquence of his case against truth and, by implication, against the Western philosophical tradition. Our minds do not �mirror� the world, he says. The idea that we could somehow stand outside our own skins and survey the relationship between our thoughts and reality is a delusion. Language is an adaptation, and the words we use are tools. There are many competing vocabularies for talking about the world, some more useful than others, given human needs and interests. None of them, however, correspond to the Way Things Really Are. Inquiry is a process of reaching a consensus on the best way of coping with the world, and �truth� is just a compliment we pay to the result. Rorty is fond of quoting the American pragmatist John Dewey to the effect that the search for truth is merely part of the search for happiness. He also likes to cite Nietzsche's observation that truth is a surrogate for God. Asking of someone, �Does he love the truth?,� Rorty thinks, is like asking, �Is he saved?� In our moral reasoning, he says, we no longer worry about whether our conclusions correspond to the divine will; so in the rest of our inquiry we ought to stop worrying about whether our conclusions correspond to a mind-independent reality.

Do Rorty's arguments offer aid and comfort to bullshitters? Blackburn thinks so. Creating a consensus among their peers is something that hardworking laboratory scientists try to do. But it is also what creationists and Holocaust deniers do. Rorty insists that, even though the distinction between truth and consensus is untenable, we can distinguish between �frivolous� and �serious.� Some people are �serious, decent, and trustworthy�; others are �unconversable, incurious, and self-absorbed.� Blackburn thinks that the only way to make this distinction is by reference to the truth: serious people care about it, whereas frivolous people do not. Yet there is another possibility that can be extrapolated from Rorty's writings: serious people care not only about producing agreement but also about justifying their methods for producing agreement. (This is, for example, something that astronomists do but astrologers don't.) That, and not an allegiance to some transcendental notion of truth, is the Rortian criterion that distinguishes serious inquirers from bullshitters.

Pragmatists and perspectivists are not the only enemies Blackburn considers, though, and much of his book is taken up with contemporary arguments turning on subversive-sounding expressions like �holism,� �incommensurability,� and the �Myth of the Given.� Take the last of these. Our knowledge of the world, it seems reasonable to suppose, is founded on causal interactions between us and the things in it. The molecules and photons impinging on our bodies produce sensations; these sensations give rise to basic beliefs�like �I am seeing red now��which serve as evidence for higher-level propositions about the world. The tricky part of this scheme is the connection between sensation and belief. As William James wrote, �A sensation is rather like a client who has given his case to a lawyer and then has passively to listen in the courtroom to whatever account of his affairs, pleasant or unpleasant, the lawyer finds it most expedient to give.� The idea that a sensation can enter directly into the process of reasoning has become known as the Myth of the Given. The late philosopher Donald Davidson, whose influence in the Anglophone philosophical world was unsurpassed, put the point succinctly: �Nothing can count as a reason for holding a belief except another belief.�

This line of thought, as Blackburn observes, threatens to cut off all contact between knowledge and the world. If beliefs can be checked only against other beliefs, then the sole criterion for a set of beliefs' being true is that they form a coherent web: a picture of knowledge known as holism. And different people interacting with the causal flux that is the world might well find themselves with distinct but equally coherent webs of belief�a possibility known as incommensurability. In such circumstances, who is to say what is truth and what is bullshit? But Blackburn will have none of this. The slogan �Nothing can count as a reason for holding a belief except another belief� can't be right, he claims. After all, if �John comes in and gets a good doggy whiff, he acquires a reason for believing that Rover is in the house. If Mary looks in the fridge and sees the butter, she acquires a reason for believing that there is butter in the fridge.� Not so fast, a Davidsonian might reply. Sensations do not come labelled as �doggy whiffs� or �butter sighting�; such descriptions imply a good deal of prior concept formation. What gives John a reason to believe that Rover is in the house is indeed another belief: that what he is smelling falls under the category of �doggy whiff.� Blackburn is obviously right in maintaining that such beliefs arise from causal interaction with the world, and not just from voices in our heads. But justifying those beliefs�determining whether we are doing well or badly in forming them�can be a matter only of squaring them with other beliefs. Derrida was not entirely bullshitting when he said, �Il n'y a pas de hors-texte� (�There is nothing outside the text�).

Although Blackburn concludes that objective truth can and must survive the assaults of its critics, he himself has been forced to diminish that which he would defend. He and his allies, one might think, should be willing to give some sort of answer to the question that �jesting Pilate� put to Jesus: What is truth? The most obvious answer, that truth is correspondence to the facts, founders on the difficulty of saying just what form this �correspondence� is supposed to take, and what �facts� could possibly be other than truths themselves. Indeed, about the only thing that everyone can agree on is that each statement supplies its own conditions for being true. The statement �Snow is white� is true if and only if snow is white; the statement �The death penalty is wrong� is true if and only if the death penalty is wrong; and so forth. As far as Blackburn is concerned, any attempt to go beyond this simple observation by trying to mount a general theory of what makes things true or false is wrongheaded. That makes him, to use his own term, a �minimalist� about truth. By reducing truth to something �small and modest,� Blackburn hopes to induce its enemies to call off their siege.

The problem with this strategy is that it leaves us with little to care about. If truth necessarily eludes our theoretical grasp, then how do we know that it has any value, let alone that it is an absolute good? Why should we worry about whether our beliefs deserve to be called �true�? Deep down, we might prefer to believe whatever helps us achieve our ends and enables us to flourish, regardless of whether it is true. We may be happier believing in God even if there is no God. We may be happier thinking that we are really good at what we do even if that is a delusion. (The people with the truest understanding of their own abilities, research suggests, tend to be depressives.)

However one feels about the authority of truth, there is a separate reason for deploring bullshit; namely, that most bullshit is ugly. When it takes the form of political propaganda, management-speak, or P.R., it is riddled with euphemism, clich�, fake folksiness, and high-sounding abstractions. The aesthetic dimension of bullshit is largely ignored in Frankfurt's essay. Yet much of what we call poetry consists of trite or false ideas in sublime language. (Oscar Wilde, in his dialogue �The Decay of Lying,� suggests that the proper aim of art is �the telling of beautiful untrue things.�) Bullshitting can involve an element of artistry; it offers, as Frankfurt acknowledges, opportunities for �improvisation, color, and imaginative play.� When the bullshitting is done from an ulterior motive, like the selling of a product or the manipulation of an electorate, the outcome is likely to be a ghastly abuse of language. When it is done for its own sake, however, something delightful just might result. The paradigm here is Falstaff, whose refusal to be enslaved by the authority of truth is central to his comic genius. Falstaff's merry mixture of philosophy and bullshit is what makes him such a clubbable man, far better company than the dour Wittgenstein. We should by all means be severe in dealing with bullshitters of the political, the commercial, and the academic varieties. But let's not banish plump Jack.