This paper discusses the nature of grammatical categories in English and Korean, giving an alternative account of some key differences between them. The goal is not so much to formulate a new theory but rather to show the syntactic mirror-image of the two languages clearly, with most ideas indebted to observations in generative grammar. It is assumed a priori that grammatical categories derive from mutual needs and the needs are represented being inherent to the lexical item when it undergoes syntactic operations. In particular, we try to deduce the EPP constraint in English on a functional basis, reasoning it out as part of a system that works closely with word order, auxiliary verbs, declaration/question formation, and adverb position.