 Explanation. Unity has been defended in the wake of authors such as Kant and Whewell as an epistemic criterion of explanation or at least fulfilling an explanatory role. In other words, rather than modeling unification in terms of explanation, explanation is modeled in terms of unification. A number of proposals introduce an explanatory measure in terms of the number of independent explanatory laws or phenomena conjoined in a theoretical structure. On this representation, unity contributes understanding and confirmation from the fewest basic kinds of phenomena, regardless of explanatory power in terms of derivation or argument patterns (Friedman 1974; Kitcher 1981; Kitcher 1989; Wayne 1996; within a probabilistic framework, Myrvold 2003, Sober 2003 and Roche and Sober 2017; see below).