ideal observer a hypothetical being, possessed of various qualities and traits, whose moral reactions (judgments or attitudes) to actions, persons, and states of affairs figure centrally in certain theories of ethics. There are two main versions of ideal observer theory: (a) those that take the reactions of ideal observers as a standard of the correctness of moral judgments, and (b) those that analyze the meanings of moral judgments in terms of the reactions of ideal observers.
Theories of the first sort – ideal observer theories of correctness – hold, e.g., that judgments like ‘John’s lying to Brenda about her father’s death was wrong (bad)’ are correct provided any ideal observer would have a negative attitude toward John’s action. Similarly, ‘Alison’s refusal to divulge confidential information about her patient was right (good)’ is correct provided any ideal observer would have a positive attitude toward that action. This version of the theory can be traced to Adam Smith, who is usually credited with introducing the concept of an ideal observer into philosophy, though he used the expression ‘impartial spectator’ to refer to the concept. Regarding the correctness of moral judgments, Smith wrote: ‘That precise and distinct measure can be found nowhere but in the sympathetic feelings of the impartial and well-informed spectator’ (A Theory of Moral Sentiments, 1759).
Theories of a second sort – ideal observer theories of meaning – take the concept of an ideal observer as part of the very meaning of ordinary moral judgments. Thus, according to Roderick Firth (‘Ethical Absolutism and the Ideal Observer,’ Philosophy and Phenomenological Research, 1952), moral judgments of the form ‘x is good (bad)’, on this view, mean ‘All ideal observers would feel moral approval (disapproval) toward x’, and similarly for other moral judgments (where such approvals and disapprovals are characterized as felt desires having a ‘demand quality’). Different conceptions of an ideal observer result from variously specifying those qualities and traits that characterize such beings. Smith’s characterization includes being well informed and impartial. However, according to Firth, an ideal observer must be omniscient; omnipercipient, i.e., having the ability to imagine vividly any possible events or states of affairs, including the experiences and subjective states of others; disinterested, i.e., having no interests or desires that involve essential reference to any particular individuals or things; dispassionate; consistent; and otherwise a ‘normal’ human being. Both versions of the theory face a dilemma: on the one hand, if ideal observers are richly characterized as impartial, disinterested, and normal, then since these terms appear to be moral-evaluative terms, appeal to the reactions of ideal observers (either as a standard of correctness or as an analysis of meaning) is circular. On the other hand, if ideal observers receive an impoverished characterization in purely non-evaluative terms, then since there is no reason to suppose that such ideal observers will often all agree in their reactions to actions, people, and states of affairs, most moral judgments will turn out to be incorrect. See also ETHICAL OBJECTIVISM , ETHICS, RELATIVIS. M.C.T.