What is murder? How should we define the word?
Elizabeth Anscombe argues that the central idea of murder is the "unjust killing of humans" (see p. 8 of her work Ethics, Religion and politics). Murder is thus not simply a legal concept. For instance, think about the horrific acts that were committed during the Nazi regime. Whether there was a written law against the Holocaust or not, one could still rightly contend that Hitler and his forces murdered other human beings on a grand scale. Anscombe points out that if we restrict "murder" to a legal concept, we will end up committing the error of Thrasymachus, namely, legal positivism.