First published Thu Sep 17, 2009; substantive revision Thu Apr 27, 2023 According to David Hume, the impossible cannot be conceived. Moritz Schlick claimed that the logically impossible, such as an explicit inconsistency, is simply unthinkable. Yet Hegel complained that it is “one of the fundamental prejudices of logic as hitherto understood” that “the contradictory cannot be imagined or thought”

First published Wed Sep 16, 2009; substantive revision Thu May 4, 2023 Peter Frederick Strawson (1919–2006) was an important and influential philosopher of the late twentieth century. His writings range over philosophical logic, the philosophy of language, metaphysics, epistemology and the history of philosophy. Across these debates, Strawson aimed to identify the most fundamental concepts involve

First published Thu Jul 23, 2009; substantive revision Thu Nov 18, 2021 David Lewis (1941–2001) was one of the most important philosophers of the 20th Century. He made significant contributions to philosophy of language, philosophy of mathematics, philosophy of science, decision theory, epistemology, meta-ethics and aesthetics. In most of these fields he is essential reading; in many of them he is