Nelson Goodman - Nominalism and Mereology

Nominalism and Mereology

Goodman, along with Stanislaw Lesniewski, is the founder of the contemporary variant of nominalism, which argues that philosophy, logic, and mathematics should dispense with set theory. Goodman's nominalism was driven purely by ontological considerations. After a long and difficult 1947 paper coauthored with W. V. O. Quine, Goodman ceased to trouble himself with finding a way to reconstruct mathematics while dispensing with set theory - discredited as sole foundations of mathematics as of 1913 (Russell/Whitehead).

The program of David Hilbert to reconstruct it from logical axioms was proven futile in 1936 by Gödel. Because of this and other failures of seemingly fruitful lines of research, Quine soon came to believe that such a reconstruction was impossible, but Goodman's Penn colleague Richard Milton Martin argued otherwise, writing a number of papers suggesting ways forward.

According to Thomas Tymoczko's afterword in New directions in the philosophy of mathematics, Quine had "urged that we abandon ad hoc devices distinguishing mathematics from science and just accept the resulting assimilation", putting the "key burden on the theories (networks of sentences) that we accept, not on the individual sentences whose significance can change dramatically depending on their theoretical context." In so doing, Tymoczko claimed, philosophy of mathematics and philosophy of science were merged into quasi-empiricism: the emphasis of mathematical practice as effectively part of the scientific method, an emphasis on method over result.

The Goodman–Leonard (1940) calculus of individuals is the starting point for the American variant of mereology. While the exposition in Goodman and Leonard invoked a bit of naive set theory, the variant of the calculus of individuals that grounds Goodman's 1951 The Structure of Appearance, a revision and extension of his Ph.D. thesis, makes no mention of the notion of set (while his Ph.D. thesis still did ). Simons (1987) and Casati and Varzi (1999) show that the calculus of individuals can be grounded in either in a bit of set theory, or in monadic predicates, schematically employed. Mereology is accordingly "ontologically neutral" and retains some of Quine's pragmatism (which Tymoczko in 1998 carefully qualified as American Pragmatism).