Abstract

The view I defend here is that ought cannot be logically derived from is. This can be justified at the level of very elementary deontic logic, as captured by the generalized logical square. This logical fact can be stated as the Hume thesis. However, the inspection of a given normative order may suggest that something exists. On the other hand, such conclusions can be fallible. In order to argue that ought is derivable from is, one must use extralogical elements and, in particular, definitions. Such strategies are in fact employed by Searle and Conte.