Abstract

The (moral) permissibility of an act is determined by the relative weights of reasons, or so I assume. But how many weights does a reason have? Weight Monism is the idea that reasons have a single weight value. There is just the weight of reasons. The simplest versions hold that the weight of each reason is either weightier than, less weighty than, or equal to every other reason. We’ll see that this simple view leads to paradox in at least two ways. We must complicate the picture somehow. I consider two candidate complications. The first, Parity Monism, is inspired by Ruth Chang’s suggestion that parity is a fourth comparative beyond the traditional three (>, <, =). This view complicates the single weight relation by allowing that the weights of reasons can be on a par. Unfortunately, Parity Monism resolves only one of the two paradoxes that afflict simple versions of Weight Monism. To resolve both paradoxes, we need our second candidate complication, Weight Pluralism. This view holds that reasons have at least two weight values (e.g., justifying weight and requiring weight) and these two values aren’t always equivalent. Parity is no substitute for Pluralism.