Defining psychology: what can it do for us?

"Psychology," like many abstract terms, is difficult to define precisely. Henriques' (this issue) argument that psychology, though unified and coherent, actually spans two realms-psychological formalism ("the science of mind," this issue) and human psychology ("the science of human behavior at the individual level," this issue)-seems likely to improve the clarity of the concept. The strongest contribution of his analysis may be its placing "psychology" in the larger conceptual framework of the Tree of Knowledge taxonomy.