AN EPIDEMIOLOGICAL MODEL OF UNIONS1

This paper applies techniques from epidemiology to the study of unions. The model implies that industries with high turnover of firms will have low unionization rates; that democratic unions which maximize the welfare of current members will be displaced in evolutionary competition by less democratic unions with more moderate wage demands; that this tendency toward moderation will be weaker in European countries where multiple unions compete for the same workers within firms; that unionization levels will be subject to rapid spurts followed by gradual declines; and that there may be one equilibrium with high unionization and long-lived firms and another with low unionization and short-lived firms. These predictions seem broadly consistent with the data