 As an empirical psychological theory, behaviorism holds that the behavior of humans (and other animals) can be explained by appealing solely to behavioral dispositions, that is, to the lawlike tendencies of organisms to behave in certain ways, given certain environmental stimulations. Behavioral dispositions, unlike thoughts, feelings, and other internal states that can be directly observed only by introspection, are objectively observable and are indisputably part of the natural world. Thus they seemed to be fit entities to figure centrally in the emerging science of psychology. Also, behaviorist theories promised to avoid a potential regress that appeared to threaten psychological explanations invoking internal representations, namely, that to specify how such representations produce the behaviors in question, one must appeal to an internal intelligent agent (a “homunculus”) who interprets the representations, and whose skills would themselves have to be explained.