Art often means nothing more than things displayed in galleries, yet there are artists whose work can also be something happening in the street, the desert, a village, on the Internet, anywhere. (These days streets, deserts, villages may be just part of the Internet.) Likewise, though it may be less obvious, art is not always things made by people who call themselves artists. Besides, artistic skills—among them lateral thinking and a tolerance of precariousness—have become part of more and more people’s job description. Don’t get me wrong. I’m not advocating for a world without artists. And as long as we’re stuck with a market economy, an art market is necessary not only to help artists earn their keep but also to sustain art’s capillary flow into the broader culture. My point is simply that once you’ve gotten the knack of art, it shouldn’t be difficult to recognize it in things not made by a professional artist. In a Molière play there’s a character who’s delighted to learn that he had been speaking in prose all his life without knowing it. Maybe you too have been doing art all along, innocently unaware.

Questioning the boundaries between art and everything else is a reflex inculcated by conceptual art. Definitions can be hazardous, but conceptual art is generally understood to have put the accent on language, and thereby shifted attention from the object to its context. Conceptual artworks have materialized not only in galleries, whether as paintings, photographs or printed texts, but also as “interventions” in everyday contexts in the form of banners, classified ads, wall posters, illustrated magazine articles and signage. For philosopher and art theorist Peter Osborne, such works repurpose “existing cultural forms of publicity (‘media’) in order to transfigure, and thereby help to transform, the structures of everyday life.” The British artist Victor Burgin called this strand of conceptualism “guerrilla semiotics.” Consider the Brazilian artist Cildo Meireles, who in 1970, during a time of military dictatorship, initiated what he called “insertions into ideological circuits.” Meireles selected simple agitprop messages, such as yankees go home!, and had them stamped onto banknotes and inscribed onto refillable Coke bottles, relying on an existing system of circulation to disseminate them widely. His emphasis was not so much on the message but its serial repetition by a system that if not for its tangential placement would have censored it.

The relation between the two dimensions of conceptualism—text and context—may seem obscure, but look at it this way: while the rules of a language and its vocabulary are supposed to be universally valid, every utterance is a specific event in the here and now of its occurrence. As soon as we start to think about the relation between the specific and the universal in language, we are liable to find our heads spinning. Is there a relation? This sense of confusion can be artistically fertile. Working when contemporary philosophy was concerned primarily with philosophy of language, conceptual artists sometimes seemed to confuse their work with philosophy (some conceptual artists became philosophers, notably Adrian Piper). But a rule of thumb helps to distinguish the two: whereas philosophy attempts to clarify concepts, conceptual art tends to show that concepts assumed to be clear remain puzzling; the intent is not necessarily to eliminate the confusion so much as to transform it into a medium of self-reflection. In 1967 Robert Smithson observed that “the power of a word lies in the very inadequacy of the context [in which] it is placed, in the unresolved or partially resolved tension of disparates. A word fixed or a statement isolated without any decorative or ‘cubist’ visual format, becomes a perception of similarity in dissimilars—in short a paradox.” This will to sustain rather than resolve paradox allies the artist more with the sophist than the philosopher.

One way conceptual artists cultivated paradox was through reflexivity. Consider John Baldessari’s Everything Is Purged From This Painting but Art; No Ideas Have Entered This Work (1966–68), a white canvas bearing its title, painted in block letters. I hesitate to say much more about it, for the same reason I’d shy away from explaining a good joke. The pleasure the painting affords is the pleasure of paradox—of trying to grasp something that on the face of it is all idea and no art, and trying to see it as all art and no idea. Baldessari’s paradox exists because of the word “this,” which lets one imagine the statement’s referent to be the canvas bearing the statement. But it didn’t need to have been the case: imagine the same lettered canvas hanging next to an Impressionist painting. In that context, “this” could be understood to mean “this one adjacent,” giving the painting’s paradox a different twist.

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It’s been more than four decades since Baldessari and other conceptual artists began exhibiting their self-deconstructing tautologies. When encountered in galleries today, such work has all the surprise of an old card trick. But conceptualism’s guerrilla spirit circulates elsewhere. Type “Occupy W…” into Google Images, and the first choice suggested will be “Occupy Wall Street.” The second will be “Occupy Wall Street Signs”—meaning, presumably, that a vast number of Google searches have been done for Occupy Wall Street signs. One of the first images called up by my search was of a sign bearing the slogan i’m so angry i made a sign. Who is the “I” who made the sign? Who knows? Images that circulate on the Internet quickly lose any anchorage to their original context. All that seems certain is that this “I” is one of the “we,” one of those who understand themselves to be part of the multitude, the 99 percent, albeit one with a sense of humor. Or is it? Detractors of the Occupy movement harp incessantly on what they see as the vacuity of its content—the lack of demands, of concrete proposals. A sign reading i’m so angry i made a sign could easily be the work of a satirist of Occupy. But then, doesn’t some of the genius of this movement lie in its ability to encompass those who disagree with it (who are also mostly part of the 99 percent)? I can’t help thinking of Tristan Tzara’s dictum, “The real dadas are against DADA.” Or as another of the signs circulating online would have it, nypd is just a layoff away from joining us!!!

What if i’m so angry i made a sign has nothing to do with the Occupy protests? That it circulates on the Internet as a sign of the protests proves nothing. As a witty self-encapsulation of the inchoate animus behind the protests, it broadcasts what Smithson would have recognized as “the inadequacy of the context”—of any context in which the sign might be read as articulating a specific demand. One might say it makes an abstract demand. Still, the sign can be said to have at least two contexts: the specific demonstration or encampment at which it is supposed to have been raised and photographed (the second act having removed the sign from that context), and the no-place of the Internet, where it has taken on a new life as an image of protest detached from any clear link to the identity of its maker or even the photographer. If there’s one trait of protest signs today that validates the notion that protest signs have become a kind of conceptual art—anything but pure chronology, the false causality of post hoc ergo propter hoc—it’s that they are now conceived of circulating in multiple contexts: the immediate one of the demonstration or encampment, and the abstract one of the Internet. The content of a protest sign is not just a message that lives and dies as part of an event but also the half-life a sign gains by being photographed and then posted online. It’s “guerrilla semiotics.”

The use of signs by conceptual artists almost always pointed away from the potential message of the sign to the condition of its circulation. In 1968 French artist Daniel Buren hired sandwich men to walk through Paris with signboards bearing, in place of advertisements, his signature 8.7 centimeter–wide white and color stripes. Not exactly a message, not exactly an image. The self-mirroring emptiness of Buren’s signboards is mirrored, in turn, by the reflexive verbal turns of many of the Occupy signs that have circulated widely. There’s not only i’m so angry i made a sign but others like i already regret choosing to carry a sign around all day and my arms are tired—acknowledgments that dedication to a cause is also a burden—and this space left intentionally blank. That last phrase is a variant of one often used in the legal documentation of Wall Street deals, floating like an island of signification in what is otherwise a blank page. On the sign, the phrase fills the entire space: unspoken intention has been raised to the level of a roar. Other similar forms of reflexivity: you know things are messed up when librarians start marching, and my clipboard can beat your billboard.

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In accordance with the more retrospective character of their work, neoconceptualists—artists who were not part of the initial conceptualist wave of the 1960s and ’70s but who constitute a second or even a third generation working in the wake of the originators—tend to erase or at least bracket the message content of existing signs. Glenn Ligon’s We’re Black and Strong (1996)—on view in his exhibition “Glenn Ligon: America,” at the Los Angeles County Museum of Art (through January 22), and traveling to the Modern Art Museum of Fort Worth (February 12–June 3)—is a massive enlargement of a news photo taken at the 1995 Million Man March in Washington. “I had a tiny image of it from a magazine,” Ligon has explained, “and started blowing it up on a Xerox machine, and I realized that when you blow something up, it sometimes gets lighter and lighter, and at a certain point, the text disappeared. I thought, well, that’s kind of what I’m interested in—these images in which there’s something there, and it gets bigger and bigger, and then that something disappears. The piece started as a four-by-three-inch photo and became a ten-by-seven-foot silkscreen piece in which the text on the banner had disappeared but returned as the title of the piece.” Ligon has also stated that the origin of the work lay in his interest in the specific absence of women from the march, which the absence of the banner text was meant to mirror. But the work took a different course. Blurring the image erased the visual evidence that there were no women in it. Instead, the disappearance of the message from the image—but with the title there to remind us what it would have been—signals a generalized pathos. The bravado of the assertion of strength has been effaced through its mere amplification: the message has become, literally, pale and weak.

Maybe Ligon’s point is simply that the content of a demonstration always exceeds and falls short of its ostensible message, that its purpose is somehow bigger but vaguer. This might be so when the message is misconceived, as I think was the case with the Million Man March. Ligon too seems to think that the march represented a self-misunderstanding on the part of those whose energies were invested in it, a failure whose symptom was the marginalization of women, which he found so notable.

Another neoconceptual meditation on demonstrations is on view (through March 11) at the Art Institute of Chicago as part of a small exhibition of three works by Sharon Hayes, a New York–based artist who made a strong impression at the last Whitney Biennial. In the Near Future (2005–09) is an ironic title for a piece that seems at first to be about the recent past. It uses thirteen slide projectors to display images of Hayes, alone, holding up protest signs on the streets of New York and various European capitals. The signs’ slogans recall past struggles, albeit ones that are not over—from ratify e.r.a. now to i am a man—along with others that seem universal: wir haben ein recht auf arbeit, rien ne sera comme avant, when is this going to end. In the snapshots that come and go on the surrounding walls, the lone protester is shown being observed quizzically or sympathetically by passers-by and sometimes being engaged by them in conversation. She is questioned by a couple of cops too. But mostly she is ignored. How serious, after all, is a one-person demonstration?

As curator Lisa Dorin writes in the Art Institute’s exhibition brochure, Hayes’s slogans “often appear jarringly anachronistic in the contemporary cosmopolitan contexts in which she reintroduced them.” It’s as if Hayes were the sole survivor among the once-hopeful warriors in these unfinished battles. As with Ligon—who has also, curiously, used the slogan from the 1968 Memphis Sanitation Workers’ Strike, i am a man, as a motif in his art—Hayes’s work rides on an undercurrent of melancholy. She stresses that we, her engaged or indifferent passers-by, are the people who have failed to crystallize into a crowd, the crowd that has failed to cohere into a movement. But there’s more than regret to the work. In the Near Future also depicts the individual who stands up, willing to communicate, to make her concerns public; she is the one person who could be many, who offers a cause around which others might gather. In counterpoint to its backward gaze, the piece offers a hopeful look forward that justifies its title.

It’s no accident that Occupy Wall Street came to life in the wake of the Arab Spring. I never believed the latter was a uniquely Arab event; that every authoritative commentary relentlessly emphasized its importance for the Arab world suggested that the powerful had every interest in keeping the enthusiasm confined to the Arab world, and every reason to fear that they could not. One of the most touching sign-images of the Occupy moment came not from Occupy itself but was nonetheless addressed to it. The image is of a man who is not taking part in a demonstration and is holding up a sign that reads from egypt to wall street don’t be afraid go ahead #occupy oakland. #occupy ows. Handwritten hashtags and all, it reminds us that the contexts in which one acts may be unforeseeable. In the face of such hope, the “left-wing melancholy” (as Walter Benjamin called it) of artists like Hayes and Ligon may seem out of place or out of date. But that’s not the case, or would be only if by dwelling on the fact that movements go awry, projects remain unachieved and desires languish unfulfilled, one were to forget that movements, projects and desires are values in themselves and can act, for some of us, as salvation from stasis. But that’s something every artist knows, and it’s an idea older than conceptualism. Leo Stein, for instance, was aware of it when he wrote of the painter he admired most that “there can scarcely be such a thing as a completed Cézanne. Every canvas is a battlefield and every victory an unattainable ideal.” He might as well have been writing about the pessimism of the intellect and the optimism of the will. If art and politics meet at all, it’s in the obligation to work concretely in the present toward an ideal that may never be fully attainable.

That tension between pessimism and optimism, the ideal and the unattainable, can lead only to one thing: the irony that permeates so many of the protest signs seen of late, and not only at the Occupy encampments, just as it permeates the work of the artists who have been dwelling on the fate of the protest movements of the recent past. Yet irony is a hopeful sign, because the beautiful enthusiasm that has expressed itself in these events has allied itself with an awareness of the disappointments that undoubtedly lie ahead. you can never find a good left-wing military coup when you need one, reads one sign, in heavily outlined red letters—which is to say that Occupy is not a project that can be imposed by force, let alone with a single stroke. Precisely because the conditions to be changed tend to persist, the will to change them must persist. Equally memorable in this context is a sign from one of the SlutWalks that took place last spring and summer: i’ll be a post-feminist in the post-patriarchy. The woman carrying that sign, I’ll wager, knows she’s in this struggle for the long haul. The sign’s eye-popping pink letters, jumping around with unruly abandon on a lemon yellow background, suggest that she still means to have fun with it.