Thermocline: how activist ideas reach the middle
Which ideas are crossing from activists to the mainstream, what carries them across, and what stops them.
In the ocean A thermocline is the thin layer where warm surface water meets the cold, deep water below. Temperature drops sharply across it, so things move freely within each layer but rarely cross between them.
In politics Ideas behave the same way. The activist layer is small, hot and fast: moral, us-versus-them language spreads quickly there, mostly among people who already agree. Most ideas never reach the mainstream below.
What gets through A few ideas do cross: when their language turns plain, when they find an institutional home (a training, a style guide, a grant criterion), or when a study gives them cover.
Where each idea stands
Speed and reach inside the movement, and outside it. The gap is the thermocline.
The thirteen tracked ideas
Each idea has its own file: its origin, foundations and spread, the roles it assigns, its use against institutions, its funding and the pushback it has met.
A 1970 psychiatry term that stayed on the academic margins for 37 years, then became a campus rulebook in under a decade.
CrossedPrivilegeA 1967 Marxist organizing idea and a 1988 women’s-studies essay arrived at the same idea.
RecedingSystemic racismDescended from “institutional racism,” a Black Power term from 1967, and pushed into mass use in a single summer.
Rolled backIntersectionalityA 1989 legal term became the organizing logic of identity politics and of federal science grants.
CrossingLived experienceA philosophy term became a credential; personal testimony now outranks evidence in many institutions.
CrossedSafe spaceOften traced to postwar group psychology as a rule for honest feedback; ended as a demand to be shielded from disagreement.
Rolled backEquityAn old legal word for fairness, redefined by activists as equal group outcomes and written into federal policy.
A German economist’s 1902 term, made a theory by a Trotskyist in 1972, became a millennial punchline.
CrossingBillionaire taxAn inequality-economics idea on the Nov. 3 California ballot; it polled well early but trailed 46–52 in October.
CrossingDemocratic socialismA century-old label, sharpened in the Cold War to set the non-Soviet left apart, revived by Bernie Sanders and now governing New York City.
From Fanon’s case for anti-colonial violence to the university syllabus, and back to violence in 2023.
CrossingSettler colonialismApplied to Israel by the PLO’s research center in 1965; now an academic field and a justification for violence.
RecedingLand acknowledgmentA ritual imported from Australia and Canada that spread through American institutions after 2019.
The extreme ideas behind the ones that crossed
Most ideas that crossed into the mainstream had a harder sister inside the movement. The sister supplies energy and the moral case; the softer version supplies reach. Knowing the sister tells you what the softer word is for.
| What crossed | The sister idea that hatched it | Status |
|---|---|---|
| Privilege | “White skin privilege” (1967), from Marxist organizers who wanted white workers to renounce it; later “abolish whiteness” and the journal Race Traitor. | Crossed |
| Safe space | “No platform”: the 1970s student-union policy of denying speakers a stage, now deplatforming. | Crossed |
| Lived experience | “Objectivity is white supremacy culture”: the claim that evidence and neutral standards are tools of oppression. | Crossing |
| Settler colonialism | “Decolonization is not a metaphor”: the demand for literal return of land, and “globalize the intifada.” | Crossing |
| Democratic socialism | “Abolish capitalism,” and the openly Marxist caucuses inside the Democratic Socialists of America. | Crossing |
| Billionaire tax | “Abolish billionaires” and “every billionaire is a policy failure.” | Crossing |
| Police reform (illustrative, not a tracked idea) | “ACAB” and “abolish the police.” | Crossing |
| Equity | “The only remedy to past discrimination is present discrimination” (Ibram X. Kendi, 2019). | Rolled back |
| Intersectionality | The “progressive stack”: ranking who may speak by identity. | Rolled back |
| Systemic racism | “The system isn’t broken, it was built this way”: every institution as white supremacy. | Receding |
| Microaggression | “Words are violence”: speech treated as physical harm. | Receding |
| Land acknowledgment | “Land back”: actual return of land, not a spoken ritual. | Receding |
| Late capitalism | Revolutionary Marxism, and “eat the rich.” | Receding |
Our coding of each concept file. Decolonize is left out because it has not crossed.
Few ideas follow the textbook life cycle
Document the lineage and the sister idea behind it.
Explain it to the middle first: say plainly what it means in practice before its backers’ softened version sets the meaning.
Pull policy and budget levers.
Press the advantage; don’t overreach.
Dashed line: the textbook path. × marks where each ran into trouble. Our coding of each concept file’s data.
Why most ideas never reach the middle
Moral-emotional language ("evil," "disgust," "betray") spreads faster, but mostly inside the group that already agrees. What wins the in-group keeps an idea from crossing.
More sharing per moral-emotional word (meta-analysis of 4.8 million posts). The original 2017 study found 20%, mostly within like-minded networks.
Higher odds of sharing for each word attacking the other side (2.7 million posts).
Sources: Brady et al. (2017), PNAS · Brady et al. (2025), replication and meta-analysis · Rathje et al. (2021), PNAS
What keeps it credible
Where grievance politics is winning, we say so.
Every claim labeled by evidence quality and linked.
Openly focused on grievance and identity politics. Accurate, not neutral.