  Questions central to the philosophical discussion of lying to others and other-deception (interpersonal deceiving) may be divided into two kinds. Questions of the first kind are definitional or conceptual. They include the questions of how lying is to be defined, how deceiving is to be defined, and whether lying is always a form of deceiving.  Questions of the second kind are normative — more particularly, moral.  They include the questions of whether lying and deceiving are either defeasibly or non-defeasibly morally wrong, whether lying is morally worse than deceiving, and whether, if lying and deception are defeasibly morally wrong, they are merely morally optional on certain occasions, or are sometimes morally obligatory. In this entry, we only consider questions of the first kind.