The duplex theory of hate is presented as a theory that applies to both individuals and groups. Indeed, evidence suggests that the basic processing system that applies to the formation and processing of impressions about groups and about individuals is similar and possibly even the same (Hamilton & Sherman, 1996). You can hate a person or you can hate a group: The feelings you experience are largely the same, although the target is different. Whether or when the feelings are identical is an open question.

Hating a group does not guarantee that you will hate all individual members of the group. For example, someone may hate a group, in the abstract, but not hate a particular member of that group. Conceivably, the person might even fall in love with a member of that group. Throughout history, spies have used this fact to their advantage. The “Mata Hari” approach involves taking advantage of the fact that someone may hate a group, but fall in love with a member of the hated group. Of course, someone may hate a member of a group but have no ill will toward the group as a whole.

The basic thesis to be presented here makes five fundamental claims.

First, hate is very closely related psychologically to love. People have always suspected there is some kind of a relation between hate and love. For example, love can rapidly turn to hate.