Properties of the Computational System can be best detected when we observe 'phenomena' where something has to be the way it is without any conceivable communicative or pragmatic reasons. And that is why researchers have focused on 'phenomena' of various forms of 'agreement' (e.g., he is sick … but not *he are sick) and cases where certain linguistic form must occur in some designated position in relation to other elements in the sentence in which it occurs (e.g., I wonder what John bought but not *I wonder John bought what). The forms prefixed by "*" are judged to be unacceptable by native speakers of English and their judgments are quite robust and uniform despite the fact that nothing seems to be terribly wrong with such forms from a communicative perspective – in fact when a non-native speaker makes such an utterance, the native speaker would most likely understand what is intended.
　　　If a language does not have what is responsible for such 'agreement' or 'obligatory (dis)placement of elements', as I maintain is the case for Japanese, following Fukui 1986, we must look elsewhere in the language to find a reflection of the Computational System, and that is the area that has been called the interface between the language faculty and the faculty of mind that is responsible for interpreting the output of the Computational System. As briefly noted in [29940], the speaker's judgments (i.e., performance) is bound to be affected by factors that are independent of the Computational System, whether it is his/her introspective judgments on the acceptability of a given sentence (under a specified interpretation) or some other manifestation of linguistic performance). By adopting the thesis that what the Computational System fails to give rise to never has the chance to be judged acceptable, can we have a hope of emerging out of the mud of this inherent difficulty with which we are faced. Suppose we proceed to discover, on the basis of the hypothesis testing that has been suggested in Hoji 2006 and is currently further developed and articulated, that some properties of Japanese are indeed due to the Computational System. We will have then learned that such properties are due to the Computational System but not due to what is responsible for 'agreement' or 'obligatory (dis)placement of elements'. It has been a rather common research practice in recent years to assume that all the properties that arguably stem from the Computational System are due to what is responsible for 'agreement' or 'obligatory (dis)placement of elements'. The general research program in which the Kyodai lectures are embedded should therefore play a corrective function to such simple-minded approaches to the properties of the Computational System. Research on a language like English, where we seem to observe two types of reflections of the Computational System, is faced with an inherent difficulty in teasing apart the two. The general significance of research on a language like Japanese thus lies in the prospect of it providing new insight that is difficult to come by from research on a language like English.