Abstract
No one nowadays would deny the importance of conceptual innovation in the growth of scientific knowledge. But how is it possible? And by this I do not mean: what kinds of social, economic, or mental develop- ments are causally responsible for promoting it? That is a question for historians, sociologists and psychologists of science to answer. Instead I shall concern myself with a more philosophical issue, namely: how can the possibility of conceptual innovation be compatible with the way in which we reason about language, meaning and understanding - i.e., what adjustments in, or constraints on, the framework of such reasoning are forced on us by acceptance of this possibility? In particular does it fit in with the project of reconstructing scientific reasoning in artificial languages like Leibniz proposed in the 17th century or Carnap in the 20th?