The Contrastivist Hypothesis (CH;Hall 2007;Dresher 2009) holdsthat the only features that can be phonologically active in any language are those that serve to distinguish phonemes, which presupposes that phonemic status is categorical. Many researchers, however, demonstrate the existence of gradient relations. For instance, Hall (2009) quantifies these using the information-theoretic measure of entropy (unpredictability of distribution) and shows that a pair of sounds may have an entropy between 0 (totally predictable) and 1 (totally unpredictable).
We argue that the existence of such intermediate degrees of contrastiveness does not make the CH untenable, but rather offers insight into contrastive hierarchies. The existence of a continuum does not preclude categorical distinctions: a categorical line can be drawn between zero entropy (entirely predictable, and thus by the CH phonologically inactive) and non-zero entropy (at least partially contrastive, and thus potentially phonologically active). But this does not mean that intermediate degrees of surface contrastiveness are entirely irrelevant to the CH; rather, we argue, they can shed light on how deeply ingrained a phonemic distinction is in the phonological system. As an example, we provide a case study from Pulaar [ATR] harmony, which has previously been claimed to be problematic for the CH.