Crosscutting and Coinciding Cleavages

A cleavage is any line that splits a society into groups with different interests or identities: ethnicity, religion, language, class, region, urban versus rural. No country has just one. What matters is how the lines sit relative to each other. A crosscutting cleavage means the groups formed by one division do not match the groups formed by another, so a person's ally on one issue is often their rival on the next. A coinciding cleavage means the divisions line up, so the same people end up on the same side of every single issue.

Crosscutting cleavages lower political temperature because they scramble coalitions. If ethnicity and religion crosscut, a Catholic and a Protestant might belong to the same ethnic group, and that shared identity pulls against treating religion as an all-or-nothing battle line. People hold cross-pressured loyalties, so no single conflict can recruit a clean, unified army. Coinciding cleavages do the opposite: if one ethnic group is also the one religion, the one region, and the one economic class, every grievance reinforces every other grievance, and the two sides become total, armed-camp identities with nothing in common to soften the fight.

This is why ethnic diversity alone predicts little. A country with ten ethnic groups that crosscut with class and region can be calmer than a country with two groups whose ethnicity, religion, and region all coincide, because the second country has manufactured one maximally hardened line instead of many partial, overlapping ones. Coinciding cleavages also tend to produce party systems built around that single frozen divide, with parties as ethnic or regional blocs, while crosscutting cleavages push party systems toward broader, multi-issue coalitions that have to bargain across lines rather than simply mobilize one bloc.