1. Diamond, L., Drutman, L., Lindberg, T., Kalmoe, N. P. & Mason, L. Opinion: Americans increasingly believe violence is justified if the other side wins. Politico (1 October, 2020).
2. Drutman, L. Breaking the Two-party Doom Loop: The Case for Multiparty Democracy in America (Oxford Univ. Press, 2020).
3. Finkel, E. J. et al. Political sectarianism in America. Science 370, 533–536 (2020). This article discusses the causes and consequences of a concept related to affective polarization — political sectarianism — which involves othering, aversion and moralization.
4. Pew Research Center. Large majority of the public views prosecution of capitol rioters as ‘very important’. Pew Research https://www.pewresearch.org/politics/2021/03/18/large-majority-of-the-public-views-prosecution-of-capitol-rioters-as-very-important/ (2021).
5. Sartori, G. Parties And Party Systems: A Framework For Analysis Vol. 1 (Cambridge Univ. Press, 1976).