Matching "versus" mechanism design

In a typical mechanism design paper the goal is to find a mechanism that maximizes the designer's objective (e.g., social welfare) subject to technology and incentive constraints. In a typical applied matching paper, by contrast, the goal is to find a mechanism that satisfies various "good properties" (e.g., efficiency and fairness). This essay discusses the relationship and tradeoffs between these two approaches. An introductory example, school choice, represents a simple win for the good properties approach. The main example, course allocation, paints a more complicated picture.