Choi, Choong-lyeol. 1999. Conditional Perfection. Studies in Modern Grammar 17, 163-178. The aim of this paper is to provide a framework to explain the so-called conditional perfection. We, first, show that the logical concept of material implication is inappropriate for the interpretation of the conditional perfection phenomena, and examine the earlier approaches, such as, Geis and Zwicky (1971), Atlas and Levinson (1981), Levinson (1983), Johnson-Laird (1983, 1986), and van der Auwera (1997), and show their defects. And we inquire into the cognitive approach which is based upon some basic concepts like worlds, cognitive principles and interpretation rules. With help of those concepts, we can solve many intricate problems well, which are caused in the proper explanation of conditional perfection phenomena as shown in section 3. This means that our linguistic theory should be constructed on the idea that our language is closely related to our cognitive activity.