An important aspect of Sellars' philosophy is his attempt to explicate the concept of thought on the "model" of the concept of speech. More specifically, Sellars has argued that the intentionality of "inner" episodes or thoughts is to be understood in terms of the "semantical" characteristics of intelligent ("nonparroting") linguistic behavior, and not the other way around as the "classical tradition" had supposed.

To avoid misunderstanding, it is important to realize that Sellars' claim, as he explains, in Aristotelian terminology, is a claim "in the order of conceiving" as contrasted with "the order of being." That is, Sellars accepts, as an integral part of his theory, the classical claim that meaningful speech is the manifestation or overt causal expression of ''inner" thoughts, but argues that our concept of such thoughts is a derivative concept, a concept which, in the order of theoretical reconstruction, is "modelled on," is an analogical extension of, the concept of meaningful linguistic behavior.