ABSTRACT
The failure of mutual understanding between two incompatible P-language communities suffices to break down the cross-language communication between them. To give a sufficient interpretation of the concept of incommensurability, the time has come to clarify the notions of the failure of cross-language understanding and cross-language communication breakdown. The notion of effective cross-language understanding will become clear in due course. Nevertheless, a few preliminary remarks about the concept, the subject, and the object of effective cross-language understanding should be helpful. A variety of accounts of cross-language propositional understanding have been proposed. Some raise doubt about the thesis that the knowledge of truth conditions is necessary for cross-language understanding. While I. Hacking emphasizes the necessary role of modes of reasoning in effective cross-language understanding, Thomas Kuhn explores the role of a categorical framework in effective understanding. To understand effectively a scientific language, one has to familiarize oneself with its lexical structure.
