Next is the Aggregate-Psychological Theory, by Ted Gurr. Which explains revolutions by psychological motivation for taking part in political violence. The key concept in this theory is how people act and how the minds of those opposing the government work. The essential arguments of Gurr's theory in understanding why revolution happen include understanding relative deprivation, interpreting people's justification and beliefs about political action, and analyzing the disconnected between the crowds capacity to act and the method in which they organize themselves.