The ubiquity of habits and rules

Under what circumstances is it necessary or convenient for an agent to rely on habits or rules? This paper focuses on the types of decision situation giving rise to their use. Even optimisation requires the deployment of rules, and for this reason mainstream economics cannot legitimately ignore these questions. The argument is that habits and rules are ubiquitous in human activity. In a new taxonomy, seven types of decision situations are considered, classified according to the type of information problem involved. Neither neoclassical nor behavioural economics can provide a complete account of the bases of habits or rules in these cases.