ABSTRACT
Timothy Smiley and I have published two papers jointly (Potter and Smiley 2001 and 2002). Their purpose was to point at problems for the abstractionist (or neo-Fregean) account of arithmetic. In the course of our work on these papers Timothy taught me a great deal about how philosophy should be written: he simply would not let me include a sentence whose meaning was not completely clear to him. The current essay, which extends the exploration of diffi culties with abstractionism from the case of numbers to that of classes, provides an opportunity for readers to judge to what extent I have taken this lesson to heart.
