 One other consequence of Hartley’s practice-oriented, “algebraic” approach to language concerns the validity of alternate languages. In the “popular” language we use every day, we talk of our choices, intentions, and resolutions, but in the “philosophical” language of the Observations, Hartley proposed we think in terms of “philosophical necessity”—in which every “voluntary” action is “excited by an associated circumstance” (OM 1, 70). Some people had, and have, no use for such talk: it denies the freedom (and indeed, the existence) of the will. Hartley argues that the use of two incommensurable languages, “popular” and “philosophical,” is not a problem, provided that we use them separately and consistently: “insuperable difficulties will arise” only “if we mix these languages” (OM 2, prop. 15). Both languages work, in their own contexts of practice.