Time consistency and time invariance in collective intertemporal choice


Recent work on collective intertemporal choice suggests that non-dictatorial social preferences are generically time inconsistent. We argue that this claim conflates time consistency with two distinct properties of preferences: stationarity and time invariance. While time invariance and stationarity together imply time consistency, the converse does not hold. Although non-dictatorial social preferences cannot be stationary, they may be time consistent if time invariance is abandoned. If individuals are discounted utilitarians, revealed preference provides no guidance on whether social preferences should be time consistent or time invariant. Nevertheless, we argue that time invariant social preferences are often normatively and descriptively problematic.

Millner, Antony and Heal, Geoffrey (2018) In: Journal of Economic Theory, 176. pp. 158-169. ISSN 1095-7235