How bounded is rationality?

Herbert Simon’s concept of ‘bounded rationality’ captures the idea that although individuals intend to behave rationally, they are constrained by limited cognitive abilities. The concept was put forward as an alternative to the assumption of neoclassical economics that individuals make decisions by maximizing utility functions.


It seems to me that maximizing utility is best viewed as a metaphor, akin to the charioteer, elephant and plane metaphors discussed in a previous post, rather than a description of actual human behaviour. It can be a useful metaphor. (I have used it on this blog to suggest that some seemingly irrational behaviours may in fact be rational.) Nevertheless, as James Buchanan has argued:

‘The modern economist who models the individual as choosing among feasible alternative bundles of goods to maximize a utility function that does exist independently of choice itself presents no evidence that such functions actually exist, and if pushed, the economist would agree that “utility” is little more than a rhetorical artifice that is introduced as an aid in explaining choice behavior within an imposed rational choice reconstruction’ (‘The Economics and the Ethics of Constitutional Order’, 1991).

It is possible to argue that all human action is rational in the sense of being purposeful, but once we acknowledge that humans have limited cognitive abilities then we have to acknowledge that they make mistakes. Economists have often recognized that people make systematic cognitive errors by incorporating arbitrary behavioral assumptions reflecting such errors (e.g. money illusion) in some of their models. This raises the question of whether efforts by economists to obtain a better knowledge of the bounds of rationality will enable them to build better models.

Jonah Lehrer’s book ‘How we Decide’, provides a highly readable discussion of the ways in which limited cognitive abilities can affect decision-making in different contexts. I decided to read the book after reading some comments by Peter Boettke on the Coordination Problem blog.

Lehrer’s main message seems to be: ‘The mind is full of flaws, but they can be outsmarted’ (p.250). He implies that a major source of error is failure to think about the kind of decision being made and the kind of thought process it requires. Insufficient reasoning can obviously result in poor decisions when the mind is strongly influenced by emotional urges and impulses. But it is also possible for the mind to choke on excessive reasoning.

It is common to hear of instances when sporting champions choke at a crucial point in a game because they suddenly become self-conscious and interfere with their performance by consciously trying to avoid mistakes. It is also possible, however, for too much analysis to lead to poor decisions in relation to choices that might be thought likely to benefit from analysis. For example, in considering a trade-off between size of home and time required to commute to work some research has suggested that there may be a tendency for people to give to give greater weight to the size of the house the more time they spend deliberating, even if the additional space is superfluous (p.144). People may often make better choices when they use their conscious minds to gather information and then trust their emotions.

Everyone knows that inexperience is a common source of error but many of us fear the unpleasant symptoms of making mistakes. One of the crucial ingredients of successful education is encouragement of children to learn from their mistakes by praising them for their efforts rather than their cleverness (p. 51-3).

The book contains a chapter on our tendencies to be fooled by feelings – loss aversion, the perception of patterns that don’t exist, the tendency to over-value immediate gains relative to longer term costs etc. Attention has previously been drawn to such problems by Dan Ariely in ‘Predictably Irrational’ (discussed here) and Richard Thaler and Cass Sunstein in ‘Nudge’ (discussed here). Lehrer suggests that the best way to avoid such errors is to be aware of them and to check feelings with a little arithmetic (p.244).

It seems to me that one of the most important contributions of ‘How we Decide’ is to draw attention to the errors that result from our tendency to surrender to ‘shoddy top-down thinking’ because self-delusion feels better than uncertainty. This is reflected, for example, in the influence of party affiliations when voters consider complex political issues. Even expert advice can be biased by adherence to frameworks that are at variance with reality. Lehrer’s suggested remedy is to embrace uncertainty, entertain competing hypotheses and to remind yourself what you don’t know.

Different readers may see different implications for economics coming out of this book. The book has reinforced my support for Oliver Williamson’s view that modes of contracting that make large demands against cognitive competence should be disfavoured (‘The Economic Institutions of Capitalism’, 1985, p.46). Governance structures will fail if they require managers to have unlimited cognitive capacities. Humans tend to be strongly influenced by moral instincts and conventions, but they are also susceptible to temptations. Another implication is that decision-making skills are likely to vary greatly among different individuals. Modellers should be wary of assuming that everyone is equally susceptible to cognitive distortions or that they have equal abilities to learn from experience. Finally, while the book provides plenty of support for the view that the rational voter is a myth rather than a useful metaphor, it suggests to me that the worm – reflecting immediate emotional responses to what politicians are saying – is unlikely to be a good predictor of voter behavior. Focus groups initially gave the thumbs down to some of the most successful shows on television.