The mass shooting at the Tree of Life synagogue in the Pittsburgh neighborhood of Squirrel Hill is believed to be the worst single attack on American Jews in our history. That’s grim—it’s 2018, a hundred years after the lynching of Leo Frank and 75 after the near extermination in Europe. Worse is the foreboding that the pulse of anti-Semitism—the harassment and violence that have begun again in Germany, the United Kingdom, and Sweden, and escalated to mass murder in France, Belgium, and Denmark—have begun to reverberate here. As Jews continually appear as the most frequent targets of religious hate crimes, the slaughter in Squirrel Hill seems to punctuate a foregone conclusion.To be sure, we’ve seen flares—in L.A. in 1999, Seattle in 2006, and Kansas in 2014. The enemies of liberal democracy, who seek to destroy it in a revolutionary conflagration, always feel an urgency and ecstasy in purging the Jews. Yet with the accelerating entropy of our politics under Donald Trump—an American president who makes speeches about corrupt “globalists” who put America second—for many Squirrel Hill feels different. Indeed, it is just one of three attempted or successful white-supremacist mass murders in the last two weeks.One consequence of the increase in militancy and growing sense of peril is that it seems to be waking people up to the fact that anti-Semitism is not the same as other forms of racial or religious bigotry. Even in a country where the apogee of exploitative racism—slavery, of African-Americans—eclipses our historical awareness of the hysterical hatreds of Europe, it has become difficult to miss that anti-Semitism is something else. It is a racist conspiracy theory, and that drives it to a very different end—the salvationist violence of mass murder and genocide.There is a sudden interest in the conspiratorial quality of anti-Jewishness among people in the center and on the left as they watch the growing obsession on the right with George Soros and “white genocide.” But becoming more aware of conspiracism is not the same as understanding it. “Anti-semitism [sic] is the source code for almost every form of religious and racial bigotry,” announced Huffington Post’s editor in chief, Lydia Polgreen, in a heartfelt tweet. “It’s the hideous seed from which hatred grows.” Poignant, but wrong. While all forms of racism share a common ancestor in xenophobia, anti-Semitism evolved in a religious struggle for survival and has followed a distinct path.Most forms of racism today depict their victims as subhuman—an “other” that is something less than “us.” But as with all conspiracy theories, the anti-Semite regards his object of obsession—the Jews—as an “other” that is both inhuman and anti-human. Meaning that Jews are so hideous and evil they revel in abominable practices no society could tolerate while, at the same time, exerting a supernatural control over the society that is forced to suffer them.Anti-Semitism doesn’t stop at segregation or exploitation. The Jews are a kind of cosmic oppressor who must be resisted and destroyed.This flows from the narrative structure of every conspiracy theory: An evil elite, operating in secret, supernaturally coordinates to promote false consciousness and enslave and exploit humankind. It is implied or stated outright that the conspirators are in league with the devil.Anti-Semitism is the name for the conspiracy theory which holds that “the Jews” are this hideous cabal. “Jews are the children of Satan,” the synagogue shooter announced on social media.Often conspiracy theories are mistakenly thought to be the preserve of the political right. While partisanship is partly to blame, that is understandable. Conspiracism relies deeply on magical thinking; in fact, there is a demonstrable overlap between belief in conspiracy theories and the occult. You need only glance at ufology to see this in practice.People on the left are just as attracted to conspiracism, but they are less direct in their reliance on magical thinking, and that makes it harder to recognize. In right-wing conspiracy theories, magic is explicit. The Protocols of the Elders of Zion draws on the European motif of the Jews gathering at night in a secret parliament to plot evil. It is no accident that this reminds of witches flying broomsticks to occulted locales to practice black magic. Combined with a romantic fixation on ethnic nations and a belief in racialist pseudoscience, this motif produced the idea of supernatural coordination among Jews to destroy humankind. In far-right parlance, one name for this is ZOG—Zionist Occupied Government—which the Pittsburgh shooter referenced often on social media.On the left, magic is depersonalized. The supernatural coordination is deflected onto “systems” and “structures” that are said to produce and perpetuate conditions of oppression. One of the basic ideas in conspiracism is that the evil elite uses its control of the mechanisms of society—the media, schools, etc.—to hide from the people the reality of their enslavement. Marxism borrowed this magical notion and gave it a fancy name—“false consciousness”—depersonalizing it by blaming it on capitalism. Workers in a capitalist system are fooled into acting against their own interests and perpetuating their own exploitation.The left today routinely transposes this idea onto matters of race and gender. It powers concepts like “privilege” and “rape culture” that supposedly rule people’s lives and determine social outcomes with or without their conscious participation. Unfortunately, Zionism has become similarly mystified. People, ideas, and institutions are said ominously to be “Zionist”—blinkered in favor of the Israeli perspective, dominated by pro-Israel Jews, or controlled outright by Israel. Zionism, and Jews, are uplinked to the magical idea of whiteness. The “Israel Lobby” becomes unmoored from any factual basis, subsumes virtually all Jews, and emanates an aura of omnipotence. Just as “globalist” has become a euphemism for Jews on the right, “Zionist” often serves the same role on the left.Conspiracism, which always carries a germ of anti-Semitism, can ignite into violence wherever it’s found on the political spectrum. This is why it is crucial to recognize it for what it is and to distinguish it from other odious forms of bigotry and prejudice. Ignoring left-wing conspiracism, or too discretely attributing the violence in Pittsburgh to Trump, will obscure the social forces that have brought us to this paranoid and populist place.