Vincent L. Anderson · Oct 19, 2026

1. Framework and scope

The framework, presumed. This essay presumes the two earlier documents: "The Diagnostic Advantage of Moral Anti-Realism" and its application to five ideologies. It takes as given three positions: moral anti-realism, impartial altruism as the overriding aim, and Sapolskian determinism. It also takes as given the paper's account of hostility as a pipeline: sentiment comes first, moralization recruits disgust and outrage, conflict manufactures felt objectivity, conviction drives intolerance and violence, and networks reward and return the output. Institutions that must codify sentiment state it as desert. The application added two further findings. Extremity is a property of how an ideology is held and enacted. And every ideology attributes free will selectively: determinism where it excuses, free will where it blames.

What the framework asks of terrorism. On these presumptions, an attack is not a free act of evil to be avenged. It is the output of a causal system, with the attacker as one node. The diagnostic question is therefore not "who deserves what?" but "which causes produced this, which amplified it, and which can be changed?" The aim is to reduce the suffering such attacks cause, including the suffering caused by responses to them.

Definitions. Two definitions are used, because the major datasets differ. Cato's 1975– 2025 dataset counts premeditated, ideologically motivated killings by non-state actors, and excludes spontaneous hate crimes (Nowrasteh 2026). CSIS counts "the deliberate use or threat of premeditated violence by nonstate actors" for political goals and broad psychological impact, including plots and non-lethal attacks (Byman and McCabe 2025). "Domestic" here means attacks on U.S. soil by people living in the United States, whatever the ideology, including homegrown jihadists. The 9/11 attacks were planned and staffed from abroad and are excluded.

Case selection. Cases were chosen on two criteria the request named. Most destructive: the highest death tolls. High-profile: attacks whose political effects reached far beyond their death tolls, such as assassinations. Historical racial terror is included, because by death toll it dwarfs the modern record.

2. The record

The modern totals. From 1975 to 2025, 208 attackers killed 3,577 people on U.S. soil in politically motivated attacks, about 0.35% of all U.S. murders (Nowrasteh 2026). Two attacks, 9/11 and Oklahoma City, account for about 88% of those deaths. Excluding both, 186 killers took 430 lives: 45% by right-wing attackers, about 32% by Islamist attackers and about 16% by left-wing attackers. CSIS's count for the past decade gives 112 victims of right-wing attacks, 82 of jihadist attacks and 13 of left-wing attacks. CSIS also found that in the first half of 2025, left-wing incidents (attacks and plots) outnumbered right-wing ones for the first time in more than 30 years, five to one. The numbers are small, and left-wing attacks remain far less lethal. CSIS's data run from 1994 to 4 July 2025 (Byman and McCabe 2025).

The deadliest and most consequential cases.

YearAttackKilledOrientation

1877– 1950Racial terror lynchings in the South4,084 documentedWhite supremacist
1921Tulsa race massacreEstimated 100–300 (state commission, 2001)White supremacist
1995Oklahoma City federal building bombing168Anti-government, white nationalist influences
2016Pulse nightclub, Orlando49Jihadist (pledged to ISIS)
2019Walmart, El Paso23White nationalist ("Hispanic invasion")
2015Inland Regional Center, San Bernardino14Jihadist
2025Bourbon Street truck ramming, New Orleans14Jihadist (ISIS-inspired)
2018Tree of Life synagogue, Pittsburgh11Antisemitic white nationalist
2022Tops supermarket, Buffalo10White nationalist ("Great Replacement")
2015Emanuel AME Church, Charleston9White supremacist
2016Police ambush, Dallas5Black nationalist, anti-police
2025LDS meetinghouse, Grand Blanc, Michigan4Anti-Mormon (investigators' reading)
2025Assassination of Rep. Melissa Hortman and her husband, Minnesota2Partisan, anti-abortion (as alleged by prosecutors; CSIS: right-wing)
2025Assassination of Charlie Kirk, Orem, Utah1Partisan (as alleged; Utah's governor described the suspect's "leftist ideology"; after the CSIS data window)
YearAttackKilledOrientation
2021Capitol attack, Washington, D.C.Contested; about 140 officers assaulted (DOJ)Election-denial, anti-government

What the table hides. The 2017 Las Vegas shooting killed 60, more than any modern attack but Oklahoma City, and is not included: the FBI's Behavioral Analysis Unit found "no single clear motivating factor" (FBI 2019). That matters. Of 173 public mass attacks from 2016 to 2020, the Secret Service found that about half were sparked by personal, domestic or workplace grievances, and only 18% by ideological, bias-related or political beliefs (NTAC 2023). The line between terrorism and other mass violence is drawn by motive, and motive is often mixed, thin or added late.

Victims by type. Recent left-wing violence has mostly targeted police and government property: 10 of 13 left-wing victims in the past decade were police officers, and 20 of 35 attacks used arson or incendiaries. Jihadist attacks have mostly targeted crowds. White supremacist attacks have mostly targeted worshippers and shoppers chosen for race, religion or ethnicity (Byman and McCabe 2025).

3. Case analyses

3.1 Racial terror lynching: the institutional branch at its extreme

Lynching is the deadliest domestic terrorism in U.S. history, and the clearest case of the paper's institutional branch. The Equal Justice Initiative documented 4,084 racial terror lynchings in twelve Southern states between 1877 and 1950. Lynchings were often public spectacles, photographed and sold as postcards. The moralization is textbook: accusations of sexual threat recruited disgust and fear (stage 2), and crowds presented the killing as justice. Codification ran in both directions. Courts and sheriffs rarely prosecuted, and Jim Crow law encoded the racial hierarchy the violence enforced, so the institutions served as proof that the hierarchy was real. The Tulsa massacre of 1921 followed the same pattern on a larger scale, beginning with an accusation against a Black teenager and ending with the destruction of the Greenwood district. On the framework, this was not the work of exceptionally evil individuals. It was a system in which sentiment, networks and institutions were aligned to produce killing, and it ended when that alignment changed.

3.2 Oklahoma City (1995): grievance codified as war

Timothy McVeigh and Terry Nichols killed 168 people, including 19 children. McVeigh timed the bombing for the second anniversary of the federal siege at Waco, in which 76 people died, and cited Ruby Ridge as well. He carried pages of The Turner Diaries, a white nationalist novel that depicts a truck bombing of a federal building. The pipeline is visible at each stage. The input was a grievance against federal force, shared across a militia network. Moralization converted it into a story of tyranny and self-defence. And felt objectivity was manufactured by conflict: each federal siege confirmed the militia narrative that the government was at war with citizens. McVeigh described the dead children as "collateral damage" (Michel and Herbeck 2001), the language of a soldier, not a murderer. That is the stage 4 output in pure form: conviction that removes victims from the count. He was executed in 2001. Whether the execution raised his standing in the militia movement is plausible but was not documented for this essay.

3.3 The replacement chain (2015–2022): contagion through networks

Charleston, Pittsburgh, El Paso and Buffalo form a linked series. Dy