This paper questions the validity of various assumptions central to treatments of featural processes such as vowel and consonant harmony, namely that features are universal, that constraints are universal, that feature scales are universal, and so on. The paper begins with a discussion of various phonetic, phonological, and typological properties of distinctive features. It goes on to discuss various properties of constraints, examining in particular the question of constraint plausibility. The class of anti-faithfulness constraints is examined in this regard, including a case study of Luo voicing polarity.