That thinker with this surname distinguished between four modes of meaning: denotation, comprehension, signification, and intension, in his 1946 book Analysis of Knowledge and Valuation, and he further developed his idea of "conceptual pragmatism," in Mind and the World Order.
One thinker with this surname critiqued the logical foundations of the Principia Mathematica and argued that the a priori is that "which is true no matter what," in his paper, "A Pragmatic Conception of the A Priori." That thinker with this surname distinguished between four modes of meaning: denotation, comprehension, signification, and intension, in his 1946 book Analysis of Knowledge and Valuation, and he further developed his idea of "conceptual pragmatism," in Mind and the World Order. Another thinker with this surname argued for a type-type psychophysical identity that he originated with David Armstrong in the paper "Mad Pain and Martian Pain," and defended his theory of modal realism in the 1986 book On the Plurality of Worlds. That thinker's best-known philosophical work uses possible-world semantics to analyze conditionals of the form "if p it would have been the case that q;" that book is Counterfactuals. For ten points, identify this surname shared by American philosophers Clarence Irving and David Kellogg.
One thinker with this surname critiqued the logical foundations of the Principia Mathematica and argued that the a priori is that "which is true no matter what," in his paper, "A Pragmatic Conception of the A Priori."
Lewis [accept either "Clarence Irving Lewis" or "David Kellogg Lewis" if given as answers]