The paper provides a micro-level theoretical explanation for empirical phenomena that unfolded over recent decades in the US and other countries (e.g., Abramowitz 2018, Pew 2022).

Many individuals’ views on different issues have shifted.
2. Views on disparate issues have become aligned in two dominant groupings.
3. Shifts and alignment have been more pronounced in one grouping – asymmetric polarization.
The explanation focuses on individuals’ multiple social identities and their interests. Identity is a person’s sense of self, the answer to “Who am I?” Individuals have multiple identities. “The same person can be, without any contradiction, an American citizen, of Caribbean origin, with African ancestry, a Christian, a liberal, a woman, a vegetarian, a long-distance runner, a historiaN...” Sen (2007). The relative importance in shaping an individual’s views and actions varies (Ben-Ner et al. 2009).

The theoretical explanation for the emergence of asymmetric polarization has several elements.

1. Shocks (events) present threats or opportunities to individuals’ identities and interests linked to them.
2. Some people link shocks to groups of people with specific identities and consider them responsible for them.
3. A shock that affects several of an individual’s identities in the same direction validates views regarding the source of the shock. This may consolidate these identities into an overarching identity. Threats and opportunities may strengthen an individual’s affinity with the social groups that form the bases for impacted identities. Threats distance individuals from the identities linked to a threat; opportunities do the opposite.
4. A shock may threaten some identities and favor others. The effect on core identities may dominate the individual’s view of the shock and its source; less important identities may be marginalized or even reversed leading to an alignment of views.
5. Threats and opportunities have asymmetric effects, with threats engendering stronger and faster reactions than opportunities (Taylor 1991; Baumeister et al. 2001). Threats cause a more significant shift in views than opportunities. Threats, therefore, also cause greater alignment of views.

Asymmetric polarization arises from individuals’ responses to shocks such as globalization, immigration, and political ascendance of minorities. These presented opportunities, threats, and a mix of both depending on the many identities and interests associated with them. For example, for some individuals, civil rights legislation presented threats to their social status derived from their racial or ethnic identity; immigration of Muslims threatened their religious identity; globalization, which some attributed to China or Jewish bankers, threatened their economic status. Such individuals reaffirmed their identities and often combined them into an overarching identity (e.g., conservative, patriot). Individuals with a mix of strong and weak identities aligned their identities with the strong ones. Individuals who found opportunities reacted favorably to the sources of the shocks, developing an overarching identity (liberal, left). Threats greater shifts than opportunities – asymmetric polarization.

Other factors such as politicians and social organizations that contribute to polarization have been studied in the literature. This paper offers an analysis focused on individual responses.

The paper suggests ideas for experiments to test the arguments discussed above.