 Lewis (1952b, 1952c, 1955, Chapter 5) outlines categorical rational imperatives of doing and thinking, or versions of one rational imperative, in various ways, formulations, and detail. The general idea is laid out briefly in AKV (Lewis (1946, 480–82). To be subject to imperatives is to find a constraint of action or thought in what is not immediate. To be rational is to be capable of constraint by prevision of some future good or ill, and subjection to imperatives is simply a feature of living in human terms. Rationality turns on consistency, and the logical is derivative from the rational. Indeed, consistency of thought is for the sake of and aimed at consistency in action, which in turn derives from consistency in willing, i.e., of purposing and setting a value on. Logical consistency turns on nowhere repudiating that to which we anywhere commit ourselves to in our thought, and consistency in general consists in not accepting now what we are unwilling to commit to elsewhere or later. Consistency in what we think and do requires and is required by conformity to principles. 