I have been reading Daniel Kahneman’s book Thinking Fast and Slow. Kahneman is a psychologist who won the Nobel Memorial Prize for Economics in 2002 for his work on judgements and decision-making. With Amos Tevsky, to whom the book is dedicated, he developed prospect theory as an improvement on expected utility theory as an explanation of decision-making in economics. They had earlier proposed the heuristics and biases model of intuitive judgements. In his later work Kahneman has developed the idea that measuring well-being is problematic because there are two selves in play, an experiencing self and a remembering self, and they don’t agree, raising some interesting questions about the pursuit of happiness.

Two academic papers are included as appendices, but the book itself is written for non-specialists. The target is water cooler conversation and gossip. We are mostly good intuitive grammarians, but we are not good intuitive statisticians or logicians. In order to recognise our mistakes we need, Kahneman suggests, on the analogy with medicine, a set of precise diagnostic labels where the labels bind illness and symptoms, possible antecedents and causes, possible developments and consequences, possible interventions and cures. With these to hand, we can improve our recognition of errors and possible create counter-measures.

Kahneman proposes a two systems model of the mind. System 1, or fast thinking, is the intuitive mind. It operates quickly and automatically and without effort, generating impressions, feelings and intentions. However, it is also impulsive and impatient. System 2, or slow thinking, is who we think we are. System 2, is the introspective mind, the mind which consciously reasons. Introspection requires attention and effort but system 2 is lazy, possesses limited knowledge and makes mistakes. Most of the time it is content to endorse the impressions, feelings and intentions generated by system 1.