The "observer" approach is investigated as a device for developing ethical theory, not for its use in private moral decision-making. Earlier discussions by Firth, Brandt, Harrison and Aiken of the impartial spectator are related to eighteenth-century British and German ethics using this theme, in order to uncover the meanings of the observer theory. Advantages and disadvantages of this approach to ethics are then examined, and the conclusion is that it does not provide a complete basis for ethical discourse but is (...) of limited use in developing some general principles in a ruleethics. (shrink)