1. This article proposes a criticism and elaboration of the theory of Natural Morphology as it relates to inflection and to inflectional change. The theoretical framework I start from is that set out at length in Mayerthaler (1981/1988), Wurzel (1984/1989), Dressler (1987) and Kilani-Schoch (1988). The concept of naturalness involved here combines Prague School notions of markedness (see Andersen, 1989) with more recent typological approaches and a semiotic framework which derives from the work of C. S. Peirce. The goal of naturalness theories in historical linguistics is to identify some constraints on language change (for example, on sound change, analogy and grammaticalization) which are, broadly speaking, functionally motivated, that is, motivated by the nature of human psychology or of human communication. Naturalness theories offer an approach to explanation of Weinreich, Labov & Herzog's (1968; 102, 186) actuation problem. Among other things, Natural Morphology proposes explanatory principles and constraints for analogy.