Weart's explanation for the democratic and the oligarchic peace is the human tendency to classify other humans into an ingroup and an outgroup, as has been documented in many psychological studies. Members of the outgroup are seen as inherently inferior and so exploitation of them is justified. Citizens of democracies include citizens of other democratic states in the ingroup. The elites of oligarchies include the elites of other oligarchies in the ingroup. However, the oligarchic elites and the democratic citizens view each other as an outgroup. Democracies viewing the elites as exploiting the rest of the population, and the oligarchic elites viewing democracies as governed by inferior men and are afraid that the democratic ideals may spread to their state.