Within a system, multiple patterns of rule combination may interact in complex ways. I present a detailed analysis of Swahili verb inflection in which simple rules, composite rules and aggregated rules all enter into intricate competition, yielding an extravaganza of deviations from canonical morphotactic criteria. At the center of this discussion are three characteristics of Swahili conjugation: (i) the polyfunctionality of verbal concords (in virtue of which the same rule is used to express the noun class of a verb’s subject, that of its pronominal object, or that of a relativized argument), (ii) the expression of negation (by means of three complementary rules), and (iii) the marking of relative verb forms (whose relativized-argument affix participates in an extensive pattern of affix counterposition). The rule-combining approach to morphotactics allows the interacting details of these subsystems to be resolved into two very general types exhibiting an unexpected degree of economy.

I discuss the general implications of the rule-combining approach to morphotactics developed in the course of the foregoing chapters. I summarize the numerous superficially problematic phenomena that the rule-combining approach resolves and I relate these phenomena to the variety of ways in which rule combinations may deviate from the canonical characteristics of a language’s morphotactics. Finally, I synopsize the set of formal definitions on which the rule-combining approach is based.

I discuss my assumptions about individual morphological rules, and then explain the ways in which rules combine. Rule composition, the default mode of rule combination, models many canonical patterns, but also models certain deviations from the canonical morphotactic criteria. Holistic rule combination, a second mode of combination, accounts for deviations from the compositional content criterion, in which a rule combination realizes more than the sum of the content that those rules realize individually. Rule aggregation, a third mode of combination, accounts for deviations from the stem operand criterion, in which a rule operates not on a stem, but on the affix introduced by the rule with which it combines. Counterpotentiation, a fourth mode of combination, accounts for deviations from the intermediate well-formedness criterion, in which the result of applying one rule is ill-formed unless its application is followed by that of another particular rule. I outline the elaboration of these ideas in the ensuing chapters.

In the rule-combining approach to morphotactics, the same rules may compose in more than one way to express more than one content. Strikingly, Murrinhpatha verb inflection allows the same rules to compose in the same linear order but in different binary groupings to express distinct content. As a consequence of this fact, Murrinhpatha verb forms exhibit a systematic pattern of ambiguity, as illustrated by pubamngankungkardungime (loosely, ‘they saw us’), in which the paucal nonsibling female suffix -ngime may relate to the verb’s object (allowing the interpretation ‘those two siblings saw us (paucal nonsibling females)’) or to its subject (allowing the interpretation ‘they (paucal nonsibling females) saw us two siblings’). As I show, this ambiguity follows from the Category Determination Principle, according to which a rule whose morphosyntactic content is ambiguous is disambiguated by the first rule with which it composes. I give a detailed demonstration that Murrinhpatha verb inflection exploits this fact.