The writer who exposed the fact that BHL had been duped was Aude Lancelin of Le Nouvel Observateur. It added to the hilarity that Ms Lancelin was a quarter of a century younger than Lévy, who is almost as celebrated for his regular appearances in Paris Match with his glamorous third wife, the actress Arielle Dombasle, as he is for his philosophising. It was fitting that a young woman should be the one to point out that the emperor was wearing no designer suit.

The embarrassment was exquisite. Lévy had "encountered the fake philosophy, swallowed it whole and regurgitated it", as one commentator noted. The spectacle sparked a storm of posts on the web poking fun at him. Lévy admitted that he had been fooled, but his response still revealed vanity rather than contrition: "Hats off for this invented but more real than real Kant, whose portrait, whether signed Botul, Pagès or Mr Anyman, seems always to be in harmony with my idea." 

This storm in a bol de café had everything: the humiliation of an ageing Left Bank superstar with an idiosyncratic way with ideas and a hairstyle to match; the schadenfreude of poorer, less talented members of the intelligentsia; and the reinforcement of the myth that some intellectuals spend their lives drifting from café to café, sunning themselves in the last pale rays of the 1960s, only to be distracted by wine, women and a job that requires little more than marketing the phenomenology of one's own life.

What is the lesson to be learned from this? Philosophers ought to be neither self-obsessed, pompous buffoons who take themselves more seriously than their research, nor corduroy-clad hermits, at least if they want to make a tangible impact, however small, on their main subject: our knowledge of ourselves. The fact that far more ludicrous real philosophies than "Botulism" are taken seriously in academic circles doesn't show that philosophy is a waste of time, but rather that it is one of the few fields in our culture where free debates are being held — at times at the expense of reason.

It was Kant himself who got the balance right. He argued that using reason without applying it to experience will lead only to illusions, while experience will be merely subjective (hence unreliable) unless it is interpreted by reason. 

The fusty old "fake" turned out to be wiser than his critic.