Mentalism versus behaviourism in economics: a philosophy-of-science perspective

Behaviourism is the view that preferences, beliefs, and other mental states in socialscientific theories are nothing but constructs re-describing people’s behavioural dispositions. Mentalism is the view that they capture real phenomena, no less existent than the unobservable entities and properties in the natural sciences, such as electrons and electromagnetic fields. While behaviourism has long gone out of fashion in psychology and linguistics, it remains influential in economics, especially in ‘revealed preference’ theory. We aim to (i) clear up some common confusions about the two views, (ii) situate the debate in a historical context, and (iii) defend a mentalist approach to economics. Setting aside normative concerns about behaviourism, we show that mentalism is in line with best scientific practice even if economics is treated as a purely positive science of economic behaviour. We distinguish mentalism from, and reject, the radical neuroeconomic view that behaviour should be explained in terms of people’s brain processes, as distinct from their mental states.