Modality and description

12 March 1948

journal article
Published by Cambridge University Press (CUP) in The Journal of Symbolic Logic

Vol. 13 (1) , 31-37
https://doi.org/10.2307/2268137

Abstract

There are logicians who maintain that modal logic violates Leibniz's principle that if x and y are identical, then y has every property of x. The alleged difficulty is illustrated in the following example due to Quine.¹A. It is logically necessary that 9 is less than 10.B. 9 = the number of the planets.C. Therefore, it is logically necessary that the number of the planets is less than 10.

Keywords

LOGICALLY
ALLEGED
DIFFICULTY
ILLUSTRATED
QUINE.1
LEIBNIZ'S
LOGICIANS WHO
WHO MAINTAIN
MODAL LOGIC

This publication has 2 references indexed in Scilit:

Notes on Existence and Necessity
The Journal of Philosophy, 1943
New Foundations for Mathematical Logic
The American Mathematical Monthly, 1937