Psychology is the science of behavior. Psychology is
not the science of mind.
Behavior can be described and explained without making reference
to mental events or to internal psychological processes. The sources
of behavior are external (in the environment), not internal (in the
mind).
In the course of theory development in psychology, if, somehow,
mental terms or concepts are deployed in describing or explaining
behavior, then either (a) these terms or concepts should be eliminated
and replaced by behavioral terms or (b) they can and should be
translated or paraphrased into behavioral concepts.