Besides affording a way of modeling deviations from canonical morphotactics, rule composition makes it possible to see apparently recalcitrant morphotactic patterns as conforming to canonical criteria if these are assumed to cover composite rules as well as simple rules. I examine an apparent deviation from the integral stem criterion in Sanskrit and apparent deviations from the rule opposition criterion in Latin, Limbu, and Sanskrit. Each of these phenomena can be reconciled with the canonical criterion from which it apparently deviates if this criterion is assumed to cover composite rules as well as simple rules. All of these are cases in which deviation from the minimal rule criterion facilitates conformity to other canonical morphotactic criteria.

Rule composition makes it possible to model an important kind of deviation from the rule independence criterion – cases in which the application of one rule is directly dependent on that of another, carrier rule. In such cases, the only use of the dependent rule is as part of a composite rule incorporating both the dependent and its carrier. Where the definition of a word form involves two carrier rules, it can further happen that the same dependent rule composes with both of them, engendering a pattern of multiple exponence that deviates from the unique sequence criterion. I discuss two cases of this sort of rule dependency: Limbu verb morphology exhibits a pattern in which dependent rules compose with their carrier rules; Sanskrit presents a pattern of the reverse sort, in which a carrier rule composes with its dependent.

Languages often present cases in which two rules together express content some of which cannot be attributed to either rule individually. The inflection of regular verbs in Breton presents several examples of this sort; holistic rule combinations are a way of modeling this phenomenon. Some instances of holistic combination have an emergent character; these are cases in which all of the forms realized by the composite of two rules happen to possess a property P that neither rule realizes on its own. In such cases, the composite is open to reanalysis as a holistic combination realizing P. Limbu verb morphology provides an example of this sort. A particularly compelling case for the postulation of holistic combinations arises in systems in which the same two rules express different holistic content in different contexts; Old English verb inflection is a system of this sort.