The mental basis of linguistic intuitions is obscure, as regards their relationship both to other aspects of language behavior, such as speaking and listening, and to an hypothesized epistemological structure, such as a ‘grammar’. In the present study, we show that experimentally manipulated differences in mental state can systematically alter the linguistic intuitions which speakers render about sentences. These results indicate that the processes underlying intuitions cannot be ignored when they are used as empirical data to test grammatical theories.
‘Inner perception ... constitutes the ultimate and indispensable precondition for the other ... sources of knowledge. Consequently ... inner perception constitutes the very foundation upon which the science of psychology is erected’ (Brentano [1874] 1973:43) ... ‘If anyone were to mount a skeptical attack against this ultimate foundation of cognition, he would find no other foundation upon which to erect an edifice of knowledge. Thus, there is no need to justify our confidence in inner perception. What is clearly needed instead is a theory about the relation between such perception and its object ... such a theory is no longer possible if perception and object are separated into two distinct mental acts, of which the one would only be an effect of the other’ (ibid., 140).