  If pure time preferences are rational, the question arises whether they are rationally required to adopt a certain form. Economists widely consider the EDU model to be the rational standard, to the extent that hyperbolic discounting is considered an indicator of irrationality worthy of policy intervention (Strotz 1956, O’Donoghue and Rabin 2015). Samuelson (1937, 160), the inventor of the EDU, was more cautious: