How Unitary Is “An Instinct”?

Abstract

A “system,” according to Paul Weiss’s somewhat aphoristic definition, “is everything that is unitary enough to deserve a name.” In choosing any name one must avoid following the example of medieval pseudoscience which confused effect and cause. When air was streaming into a vacuum, a “horror vacui” was made responsible for that effect; the “phlogiston” was assumed to explain burning, and so forth. In exactly the same way, vitalistic psychology, rampant at the turn of the century, used terms such as the “escape instinct,” the “reproductive instinct,” and even the “instinct of self-preservation,” deeming this to be a sufficient explanation of behavior. This seemed legitimate as long as an “instinct” was regarded as a preternatural factor, neither standing in need of nor accessible to a causal explanation.