 Right at the heart of Lewis’ philosophical system, then, are several theses that weren’t original to Lewis, but the critical discussion (and sometimes rejection) of which, often in the form Lewis gave to them, was central to much analytic philosophy in the last half of the twentieth century. Among them are: (1) a sharp analytic/synthetic, a priori/ a posteriori distinction, (2) reductionism concerning the meaning of a physical object statement to the actual and possible sense experiences that would confirm the statement, (3) a foundation for all empirical knowledge in our direct apprehension or immediate awareness of the given character of experience and our recollections of it, and (4) the division of experience into its given content or character, on the one hand, and the form we impose on it, or the concepts in the light of which we interpret it, on the other. (Quine (1951 [1953]) famously called (1) and (2) the “two dogmas of empiricism”; Sellars (1963) called (3) the “myth of the given”; and Davidson (1973–1974 [1984]) called (4) the “third dogma of empiricism”, although in Lewis’ mind (4) may owe more to Kant—on whom Lewis taught a course regularly at Harvard—than to the empiricists.)