The distribution of the raised variants of the Canadian English diphthongs is standardly analyzed as opaque allophony, with derivationally ordered processes of diphthong raising and of /t/ flapping. This paper provides an alternative positional contrast analysis in which the pre-flap raised diphthongs are licensed by a language-specific constraint. The basic distributional facts are captured with a weighted constraint grammar that lacks the intermediate level of representation of the standard analysis. The paper also provides a proposal for how the constraints are learned, and shows how correct weights can be found with a simple, widely used learning algorithm.