The emergence of a white supremacist ”alt-right” movement is a deeply disturbing moment in US politics, and commentators are struggling to make sense of what motivates and how to define the group. But for insightful analysis on the psychology behind the alt-right’s trolling and bigotry, some of the best writing comes not from contemporary thinkers, but a text written 70 years ago.

As was noted on Twitter, French philosopher Jean-Paul Sartre’s essay Anti Semite and Jew, first published in 1946, is unnervingly relevant today. The essay analyzes the impulses behind anti-semitism, showing that it’s not grounded in facts about Judaism or the Jewish community, but in an irrational hatred that exists for itself and feeds on itself. It contains the famous line: “If the Jew did not exist, the anti-Semite would invent him.”

William McBride, philosophy professor at Purdue University, says that the text, although focused on anti-Semitism, is “definitely” applicable to the broader racism of the alt-right movement.

Sartre describes racists as delighting “in acting in bad faith,” a term which he developed in his broader existential philosophy. “[Bad faith] is a lie you tell yourself,” says McBridge. “You pretend you’re doing something authentically when in fact you’re not. You know it at one level but not at another.”

So racists posture at reason, authenticity, and noble intentions when in fact they know, deep down, that what they’re doing is hateful.

McBride believes online communication can exacerbate the bad faith posturing of racists; after all, social media is very much focused on posing and comes with little true responsibility. Responsibility, he explains, is a key component of Sartre’s philosophy: We are entirely free and so hold ultimate responsibility for our actions. Those who act in bad faith are attempting to eschew responsibility, which is encouraged by the lack of accountability online.

“There’s so much lack of self-examination, so much posturing,” he says. “They’re hardly likely to be held responsible unless they advocate murder or something like that. Otherwise they can say pretty much whatever they like.”

Unfortunately, while the internet may have tweaked the way hatred is expressed, Sartre’s writing shows that bigoted behavior, over the decades, remains largely unchanged.