Rules and blocks

In a series of publications, Stephen Anderson developed the idea that the definition of a language’s inflectional morphology involves blocks of realization rules such that (i) realization rules’ order of application follows from the ordering of the blocks to which they belong and (ii) realization rules belonging to the same block stand in a relation of paradigmatic opposition. A question that naturally arises from this conception of rule interaction is whether it is possible for the same rule to figure in the application of more than one block.  I discuss two systems of verb inflection exploiting exactly this possibility -- those of Limbu and Southern Sotho.  In order to account for the special properties of such systems, I argue that in the definition of a language’s inflectional morphology, one rule may be dependent upon another, and that in such cases, the dependent rule may figure in the application of more than one block precisely because the “carrier” rules on which it is dependent differ in their block membership.  In formal terms, this means that the definition of a language’s inflectional morphology may draw upon principles of rule conflation by which a dependent realization rule combines with its carrier rule to form a single, more complex rule, typically occupying the same block as the carrier rule.  I further show that there is considerable independent motivation for the postulation of these principles.