Ideal observer theory states that an action is morally right/wrong if a theoretical, impartial, ideal observer has a positive or negative attitude towards said action, and that moral claims express propositions about the attitudes of said observer. However, wouldn't the existence of its attitudes diminish its impartiality and rationality? And why would it make moral judgements in the first place? What is the motivation for it to do so unless there is already moral truth outside of it?

  • are you asking whether a truly ideal observer can exist? i assumed it was a hypothetical construct, so that it may not matter.
    – andrós
    Commented Apr 6 at 14:49
  • oh, ethics really is aesthetics
    – ac15
    Commented Apr 6 at 15:00
  • @user66697 I'm asking why this ideal observer would make a moral judgement in the first place. This doesnt assume it exists
    – edelex
    Commented Apr 6 at 16:14
  • i don't think it's circular, at least not in any fatal way, to define the ideal observer as someone that can make judgments, even supposing she must not just be whoever makes the right judgments
    – andrós
    Commented Apr 6 at 21:39
  • Good point, a common criticism of Firth's "disinterested" and "dispassionate" observers is that they are indifferent and morally impotent, see SEP. However, "ideal observer" is only meant as a heuristic discovery device. Morality itself may well be objective, but the question remains of how do we obtain trustworthy moral judgments. Firth's idea is that we have some primal moral intuition that gets obscured by ignorance, inaptitude, biases, etc., and this is an intellectual device for tapping into it.
    – Conifold
    Commented Apr 7 at 6:43

1 Answer 1


In a sense yes, the judgements of the ideal observer do demonstrate partiality, but it is the partiality of a rational, well-informed observer with no particular axe to grind. Clearly, the rational observer still has to make judgements, weighing the pros and cons of options, but the suggestion is that if you assume those judgements are made calmly and rationally by someone in possession of all the facts, that is as good a basis as any other for deeming that the judgements are 'morally right'.

  • But why does it have to make judgements?
    – edelex
    Commented Apr 6 at 16:15
  • The observer doesn't have to. The theory simply assumes that if the observer were to make such a judgement, that would be a good basis for determining whether something was morally right. Commented Apr 6 at 16:38
  • Human psychology is relevant to the 'ideal observer' (she must make relevant judgments that we are capable of), but even supposing we cannot make subjective impartial judgments (which is reasonable), that doesn't mean the ideal observer cannot, that impartial judgments simply cannot exist.
    – andrós
    Commented Apr 6 at 21:22
  • @user66697 I think we are at cross purposes. You and I are using partial and impartial in different ways, so I agree with you more than our words might suggest. Commented Apr 6 at 21:27
  • ok i meant to comment on the question, not your answer, but that's the one thing i was trying to avoid, so apologies
    – andrós
    Commented Apr 6 at 21:34

You must log in to answer this question.

Not the answer you're looking for? Browse other questions tagged .