Anonymous. (2026). Individual-level causal effects of algorithmic animosity amplification on affective polarization, operating through a mechanism present on multiple platforms reaching a supermajority of US adults, make it plausible — though not formally demonstrated — that the population-level contribution exceeds 10% of observed affective polarization growth. Isonomia. https://www.isonomia.app/a/fiZQ0IuU@bec6a5b62e7abe4cecb2bb40fc1696662e0927bdc29eeaf6c770f787d3a406d0