The article deals with some of Luther’s disputes from logical and semantic perspectives. It shows how Luther made use of some parts of medieval logic and semantics in order to elucidate the relationship between philosophy and theology. The author argues that Luther introduced the conception of "new language" which offers a basis on which to differentiate between theology and philosophy. This difference between "old" and "new" language is a matter of a different significations of the terms used. From the exploration of the relationship between the two languages comes the conclusion: Luther’s theologically differentiating between theology and philosophy corresponds with his differentiating between "new" and "old" language.