Another approach incorporates the notion of suffering into the definition. The definition offered by the Oxford English Dictionary incorporates suffering as a necessary condition, with "the painless killing of a patient suffering from an incurable and painful disease or in an irreversible coma", This approach is included in Marvin Khol and Paul Kurtz's definition of it as "a mode or act of inducing or permitting death painlessly as a relief from suffering". Counterexamples can be given: such definitions may encompass killing a person suffering from an incurable disease for personal gain (such as to claim an inheritance), and commentators such as Tom Beauchamp and Arnold Davidson have argued that doing so would constitute "murder simpliciter" rather than euthanasia.