This is the second in a series of web columns about artists by Sarah Thornton, author of Seven Days in the Art World and chief writer on contemporary art for the Economist.

Joseph Beuys said, “Everyone is an artist.” It’s a generous comment from a performance artist and sculptor who played the role of a teacher for many years. If it weren’t complete nonsense, it might be empowering. For the man who positioned himself as a shaman and came to be regarded as the patron saint of contemporary art in Germany, however, it could be seen as obfuscation. If anybody understood the irony that being an artist is a craft, it was Beuys.

Have you ever noticed that, upon graduation from art school, many artists are hesitant to declare themselves an artist? If asked what they do, they hedge. “Iʼm spending time in my studio,” says one. “I make small videos,” replies another. If questioned about the label “artist,” they will say things like “I donʼt want to be perceived as a wannabe” or “It feels ʻpretentiousʼ in the strict sense, like Iʼm pretending.” Despite the ever-increasing professionalization of the art world, it would appear that a degree is not enough. Being an artist is not an accreditation or even a job, but an identity that requires some clout.

Discourses of authenticity are endemic to the art world. In a sphere where anything can be art and good artists create their own criteria of quality, credibility is the crux of being an artist. Even if they deny it, art-world insiders surreptitiously look back and forth between artists and their work to ascertain whether artists are aligned on the positive side of a set of inchoate oppositions: innovative versus derivative, honest versus insincere, authoritative versus unreliable, confident versus unconvincing.

When the artist is young and hasn’t yet produced many bodies of work, art professionals even do “a risk assessment based on their character,” as Iwan Wirth, a dealer whose gallery Hauser & Wirth is in Zurich, London and New York, once told me. The walk and talk of the artist, like the size and colour of a sculpture, have to persuade. Whether they have loud, large-scale personas or subdued, reclusive selves, believable artists are always protagonists, never secondary characters who fall into being “types.”

Incarnations of credibility have changed markedly over the years. In the 1950s, abstract expressionist painters like Jackson Pollock became models of authenticity. A heavy drinker from a working-class background, Pollock appeared to pour his emotions onto the canvas. Originality was associated with being raw, deep, passionate and virile in paint-spattered jeans. Nowadays, strains of this modus operandi are adopted and parodied by artists such as Paul McCarthy and Jonathan Meese.

The 1960s ushered in a new range of believable behaviours. Some were linked to political or academic agendas; others were based on the ironic revelation of artifice. Andy Warhol was most influential. Not only did the artist talk in cool sound bites and cultivate a public image as a star-struck consumerist, he tried to give the impression that there was no “real” Andy. “I’m sure I’m going to look in the mirror and see nothing,” he wrote in The Philosophy of Andy Warhol. “People are always calling me a mirror and if a mirror looks into a mirror, what is there to see?” Today, Jeff Koons and Cindy Sherman work in this vein in their very different ways.

Credibility is subject to subtle forms of male bias. In the midst of an interview with Marina Abramović, I was startled to hear her distinguish between her “high” self and her “low” one. During The Artist is Present, her 2010 performance in the atrium of the Museum of Modern Art in New York, Abramović sat silently all day, every day, for two and a half months, having staring, one-to-one encounters with members of the public. That was her high self. Her low self is less disciplined; she concedes that it is “full of contradictions” and “things that you are ashamed of.” Shame? Really? “I love fashion,” she admits. “In the 1970s, that made you a bad artist.” Needless to say, a love of cars or strip bars doesn’t tend to have a commensurate effect.

Many artists go for long stretches without any professional endorsement. Some never obtain it. After a consensus of confidence in an artist’s work waxes, it often wanes. Art-world insiders are ruthless, picking and choosing where they invest their conviction every time they walk into a studio, museum or art fair. As a result, being an artist requires immense self-belief.

Confidence is such an issue for contemporary artists that many, going back to Marcel Duchamp, have presented themselves literally as “confidence artists.” They may be admitting that artists who integrate ready-mades into their work are thieves or that their challenges to the visual mainstream put them in the position of being symbolic criminals. Or perhaps they are reflecting the outsider view that contemporary artists are charlatans and hustlers. Laurie Simmons, the photographer and video maker, once told me that self-belief sometimes involves a degree of self-deceit. “When you are starting out as an artist,” she says, “you have to con yourself.”

Artists are often said to have big egos, but I think that they need to tread a careful line. Arrogance can be useful, but pride can be debilitating. Confident charisma is a plus, but unrefined self-importance gets in the way. Almost all artists are exhibitionists to some extent. They fear being “nobody” and appreciate being noticed, but the best yearn to achieve rather than “be.” Needless to say, artists are not universally narcissistic. The term “vain” doesnʼt just mean conceited; itʼs also a synonym for ineffective, hopeless and unsuccessful. Whatever the case, it seems to me that ambitious artists with long-term careers adopt projects that feel larger than themselves.

Of all the artists I have encountered, Ai Weiwei stands out as a man with a calling. Some might think that, as an internationally famous artist-architect-blogger–political activist, Ai is breaking the mould. Of course, in some ways, he is. But he also embodies an odd, old romance. Heʼs a vanguard artist in the strict sense because he lives in a country where tight limits on free speech and ubiquitous state propaganda mean that it is still possible to occupy such a position. However, he is not only a symbolic criminal; Chinese officials have treated him as an actual one, subjecting him last year to some 50 interrogations during an 81-day imprisonment.

I’ve interviewed Ai twice: once in London when his 150-tonne Sunflower Seeds installation opened at Tate Modern and once a few weeks ago in his studio in Beijing where he discussed the content of his interrogations for a piece that I was researching for the Economist.

While in China, I discovered that there is no equivalent term in Chinese for “credibility.” Ai explained that, in ancient times, the Chinese language had a word for this kind of belief and trust, but it had fallen out of use under communism. As his self-portraits reveal, Ai is aware of the craft of self-representation. Although we didn’t discuss it, I would expect that he would admit that being an artist is one of the many executional issues that an artist has to resolve and that artists need to be masters at suspending our disbelief. When I asked him what “authenticity” means to him, he seemed to associate it with telling the truth. “It is a habit,” he said. “It is a road we are comfortable with.”