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.

Affix counterposition has two subcases: in the first (exemplified by the inflection of reflexive verbs in Lithuanian), an affix that is suffixed to the stem in some words is suffixed to a prefix in others; in the second, mirror-image case (exemplified by Noon adjective concord), an affix that is prefixed to the stem in some words is prefixed to a suffix in others. Rule aggregation models the phenomenon of affix counterposition as a deviation from the stem operand criterion involving a rule of affixation R whose operand is ordinarily a stem (when R isn’t aggregated) but is instead an affix (when R is aggregated to the rule introducing that affix). Rule aggregation brings affix counterposition into conformity with the affix directionality criterion. Nevertheless, there are real deviations from the latter criterion: some languages have true ambifixes that actually function as prefixes in some word forms but as suffixes in others. Gurma noun-class inflection exemplifies this possibility. Moreover, the morphotactics of Italian pronominal affixes involves a significant interaction between true ambifixation and rule aggregation.

In this chapter, I discuss the preliminary assumptions of the rule-combining approach to morphotactics and advance the two fundamental hypotheses that underlie it: the morphotactic holism hypothesis and the morphotactic variety hypothesis (Section 1.2). In Section 1.3, I review previous proposals that provide empirical support for the morphotactic holism hypothesis, which (unlike the morphotactic variety hypothesis) is not a novel idea. In Section 1.4, I discuss the nature of canonical morphotactics, for which I introduce ten criterial characteristics, construed in rule-based terms. In Section 1.5, I give examples of phenomena that possess these characteristics as well as of phenomena that do not apparently possess them. The morphotactic phenomena to be analyzed in the following chapters deviate from some of these canonical characteristics, but reinforce conformity to others provided that a rule-combining approach is assumed. In Section 1.6, I anticipate the range of topics to be discussed in subsequent chapters.