The philosophy of artifacts is as marginal as it is one-sided. The majority of contributions to it are asides in works devoted to other subjects and focus on one characteristic feature: that artifacts are objects with functions. Indeed many artifacts, such as screwdrivers and toasters, come in functional kinds. Perhaps for this reason, philosophers elevated functions to the essences of artifacts or have developed general theories of function to describe artifacts along with their main subject: biological items. Most such theories present one monolithic notion of function that applies to both. Dissident voices claim autonomy for artifact functions, or at least a small measure of conceptual independence, but it is seldom questioned that a theory of artifacts consists merely of a theory of artifact functions.