Summary

Systems of phonological alternations in most languages involve a number of rules. This interaction means that you must discern the effects of individual rules, rather than subsume all alternations under one complex do-everything rule. A rule changes a given set of segments in a uniform manner, in a specified environment. So even when a language like Bukusu has a number of rules pertaining to sequences of nasal plus consonant – rules which have in common a single context NC – there may be quite a number of specific rules that apply in that context. Besides identifying what rules exist in a language, you must also determine what the proper ordering of those rules is. The correct order of a pair of rules can be determined by applying the rules very literal-mindedly in both of the logically possible orders.