I discuss different kinds of deviation from the parallel sequence criterion; I illustrate with detailed examples from Fula, Udmurt, and Eastern Mari. In Fula verb inflection, rules of subject and object marking involve a default applicational sequence that is overridden in specific circumstances by the opposite sequence of application; this deviation can by modeled by postulating two patterns of rule composition, one realizing the default sequence and the other overriding that default. Udmurt noun inflection is different, since it involves two patterns of rule composition that do not stand in a default/override relation but are instead simply complementary. Nevertheless, the Fula evidence and the Udmurt evidence both conform to the unique sequence criterion. The declensional morphology of Eastern Mari, by contrast, deviates from that criterion, since it allows alternative acceptable sequences of rule application; in the rule-combining approach to morphotactics, these can be seen as involving alternative patterns of rule composition realizing the same morphosyntactic content.

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.

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.