Personal goals, utility, and probability

In the previous chapter we discussed the distinction between rationality₁ or personal rationality, and rationality₂, or impersonal rationality, and introduced our argument that the rationality of human thought and reasoning is not sensibly to be judged by the strictures of formal logic alone. Because we have emphasised instead the idea of successful goal-directed behaviour, it might seem that rationality could be judged instead by decision theoretic principles referring to subjective probabilities and utilities. But we will show that whereas normative decision theory—an impersonal system—deals with the objects of a rational₁ approach, such as degrees of belief and utilities, it has serious deficiencies in accounting for behaviour that leads to the achievement of personal goals.