The present paper will argue what can be considered to be principled elements of the initial state S/sub 0/ of the Faculty of Language, which are called the Interface Condition (IC), and how far we can take the strongest minimalist thesis (SMT), which aims to offer principled explanation of language in terms of IC and the principle of efficient computation, to linguistic analysis. We will discuss implications of label-free phrase structures, required by the strong version of the Inclusiveness Condition, and possibilities of crash-free syntax, required by the condition of efficient computation. I will point out problems of Chomsky's assumption that an externally Merged expletive there is a head, which, as a probe, undergoes agreement with the goal T. I will present several advantages we obtain if we maintain A and A' distinction, and assume that wh-movement to the outer [SPEC, υ] is an A'-movement like wh-movement to [SPEC, C].