Rationality is Pretty Hard

The problem is that the notion of rationality arises in a variety of disciplines.9 For example, philosophers and psychologists regard a rational process as one where beliefs, actions, etc., are adopted for appropriate reasons. This type of rationality has been dubbed philosophical or psychological-rationality (P-rationality).10 Economists regard behaviour as rational when it maximises a quantity (usually some kind of utility), no matter what process produces the behaviour. This may be called economic-rationality (E-rationality). Biologists are interested in principles of maximisation that relate to fitness (see Chapter 1), and this may be called behavioural-rationality (B-rationality). Whereas P-rationality refers to a process, E-rationality and B-rationality relate to behavioural outcome. Thus I see my dog, Border, catching and eating a lizard, I can ask whether a rational process is involved (P-rationality), whether she is behaving efficiently and economically (E-rationality), and whether she is improving her genetic fitness (B-rationality). If she catches the lizard in an unthinking reflex manner, then the first answer is no. If she catches it with speed, skill, and little energy expenditure, then the second answer might be yes. If she eats a lizard that is poisonous, then the third answer might be no.

McFarland, David (2008–02–28). Guilty Robots, Happy Dogs: The Question of Alien Minds (pp. 89–90). Oxford University Press. Kindle Edition.