Philosophical behaviorism is circular
Any attempt to define mental states in terms of behaviorial dispositions relies on further mental states. But this is a circular definition of mentality.
For example, if the desire to eat chicken is defined as a disposition to eat chicken when chicken is present, then this presupposes belief that chicken is edible, which presupposes a belief that chicken is non-poisonous, and so forth.
Roderick M. Chisholm, 1957.