US Edition It is stepping on hallowed ground to criticise Freud, the father of psychoanalysis, in a country where top analysts and philosophers are still treated as stars.
But Michel Onfray has accused the champion of the unconscious mind of lying about the success of his treatment and being a misogynist homophobe obsessed with sexual abuse.
He goes on to attack the whole exercise of psychoanalysis as the last untouchable religion revered by "stars and footballers."
"Who else would still have the time to pay in cash to lie on a couch twice a week before some guy who's half-asleep?," Mr Onfray said as his controversial book Twilight of an Idol, the Freudian Fabrication was published.
French psychoanalysts' response was immediate and fierce.
Leading the charge was Elisabeth Roudinesco, who blasted his book as "a rag stuffed full of errors and shot through with rumours".
Mr Onfray claims that Freud claims to have cured 18 patients as proof that his theories could be successfully applied. On closer inspection, however, documents prove this to be a total fallacy, he contends.
"Take Anna O., one of his most famous cases, a 21-year old woman suffering from hysteria, paralysis and hallucinations. Freud based much of his theory on her cure via hypnosis and talking through her ailments. In fact, writes Mr Onfray, "Anna O. (real name Bertha Pappenheim) was never cured and suffered repeated relapses". Despite this, he claimed, "Freud would shamelessly claim throughout his life that Anna O.'s treatment was a success."
Freud, he goes on, is not the inventor of a revolutionary therapeutic science but a charlatan who "transformed his personal fantasies into universal scientific truths" and has a "pathological" obsession with incest and the Oedipus complex.
To cap it all, he accuses Freud, who lost four sisters in Nazi concentration camps, of being anti-Semitic and a "road companion" of fascism, as he notably wrote a dedication to Mussolini which says: "To Benito Mussolini, with respectful greetings of an old man who recognises in the leader a hero of culture".
Miss Roudinesco denied Freud was a fascist. "You have to put all that into context...(Freud) in no way adheres to fascism and never made an apology for authoritarian regimes," she wrote, before accusing Mr Onfray himself of "rehabilitating pagan theses of the French extreme-Right".
"Onfray insults us when he says psychoanalysis doesn't cure," said Serge Hefez, another analyst. "What are we all doing in our clinics, our family and marriage guidance centres, our day hospitals...if it is not helping a person become once again the actor of his own history?"
Mr Onfray pre-empted the attack, however: "As soon as you touch Freud, certain people will start a fight to maintain the mythologies," he warned.
Asked whether Freud had any saving graces, he replied: "There are also people who find that some things can be salvaged from Nazism. Well I don't defend Hitler's autoroutes."
Some psychoanalysts took the attack on the chin, but said Mr Onfray was misguided. "Yes Freud made mistakes," wrote Philippe Grimbert, who conceded that he failed to openly criticise Hitler's rise, but would Mr Onfray have done so in Nazi Austria?
"He often used his own inhibitions, dreams and fantasies to invent psychoanalysis, but that doesn't make him a sick man seeking to justify his deviancy".
Yes, he overstated some of his achievements. "But it's an insult to all those who went through analysis to qualify it as an intellectual fraud...Michel Onfray is right, psychoanalysis doesn't cure people...it saves (them)!".