Summary

Answering a simple problem, namely how to represent contour tones, led to ideas which not only solved the problem of contours, but also solved a whole array of problems related to tone. Since there is no reason to think that there should be a special theory just for tone, a natural development of these changes applied to tone was a general application of the autosegmental idea to all of phonology. This resulted in sweeping changes to the theory of phonology, and has resolved many earlier problems in how to state rules in a constrained manner. This generalization of the results in one area to an entire subdiscipline is typical of the progression of scientific theories.