Ideal observer theory is the meta-ethical view which claims that:
- Ethical sentences express propositions.
- Some such propositions are true.
- Those propositions are about the attitudes of a hypothetical ideal observer.
In other words, ideal observer theory states that ethical judgments should be interpreted as statements about the judgments that a neutral and fully informed observer would make; “x is good” means “an ideal observer would approve of x“.
”The main idea [of the ideal observer theory] is that ethical terms should be defined after the pattern of the following example: “x is better than y” means “If anyone were, in respect of x and y, fully informed and vividly imaginative, impartial, in a calm frame of mind and otherwise normal, he would prefer x to y.”