Perceived Irrationality Is Rooted in Actual Rationality

#model1 mention

Rationality is an evolved strategy. This means current rationality is the result of Adaptation, i.e. relative evolutionary success of its component dispositions in past environments, or of random deviation from adapted dispositions.

It follows that every theory of rationality must show that current dispositions are either

Building on this, there are at least four possible Explanations for seemingly irrational human behaviour:


The underlying dispositions have originally evolved to be rational, but are maladapted to current System Dynamics (e.g. Climate and Ecological Breakdown) – we need to correct our mental Models of these systems in order to correct our everyday behaviour.

[B]ecause the human brain is a highly complex, slowly evolving organ, human beings are likely to exhibit an ‘adaptive lag’, meaning that much of human behaviour is sub-optimal in modern environments.Brown & Richerson (2013), 133


Dispositions are in fact adapted to actual system dynamics (e.g. gambling, wealth), which science doesn’t understand adequately – we need to correct our scientific models of these systems, not our everyday behaviour.This is the position of the fast-and-frugal heuristics school of thinking about rationality (see e.g. Gigerenzer & Sturm 2011) which criticises the concept of cognitive biases as misrepresenting actually rational behaviour as irrational by neglecting the real-world context of this behaviour. Similarly, ergodicity economics (see e.g. Peters 2019) show that the behaviour of economic actors might be rational when it deviates from what our economic models predict as rational because these models are based on an incorrect assumption about probability distributions.

[H]euristics can lead to judgments that are as accurate as or even more accurate than strategies that use more information and computation ….Gigerenzer & Sturm (2011), 243


Dispositions seem irrational due to a misalignment between supposedly objective goals of a system and what it subjectively perceives to be its goals.

An important driver for this is Ideology: It creates an incentive system to behave in a way that is not conducive to people’s objective well-being or security, but to optimise for externally imposed goals, e.g. consumption in Consumerism.

In this case, people’s behaviour is rational within the ideological context, but irrational without.

Population-level Selection

Irrational behaviour is adaptive in stochastic environments and thus gets selected as rational on a population level, although it is (currently) irrational on an individual level.

This is the reason why Cities are innovative because they tolerate crazy people.