Note 74 — Chapter IV

So long as we are confined to simple terms the relations of contrariety and repugnancy cannot be expressed formally or in mere symbols. But it is otherwise when we pass on to the consideration of complex terms. Thus, while XY and not-X or not-Y are formal contradictories, XY and X not-Y may be said to be formal repugnants, XY and not-X not-Y formal contraries (in the narrower of the two senses indicated above).