Impulsivity: Why reasonable people do unreasonable things

Abstract

People know some actions are wrong to perform, but still perform the actions. Why do these reasonable people do unreasonable things? We have discussed this question using an interdisciplinary approach. Insights from philosophy and biology proved useful since both disciplines deliver insights on irrationality. Philosophers discuss the concept of akrasia as an example of irrationality, which means acting against better judgement. Addiction, using drugs compulsively despite negative consequences, is a focus of biologists when it comes to irrational behaviour. We have integrated the findings on akrasia and addiction to deduce a more comprehensive understanding of why reasonable people do unreasonable things. We propose a model that shows how unreasonable behaviour arises. Behaviour is motivated by a desire to perform a certain action and representations of possible actions. A desire is influenced by past experiences and is determined by the brain. One can desire to perform an action that has the experience of pleasure as a result. The amount of pleasure an action generates can be overrated, however. Besides desire, long-term goals and deliberations play a role as input for decision making. In akratic and addicted people desire is more dominant than this deliberation, resulting in unreasonable behaviour. We use the description ‘impulsivity’ to explain unreasonable behaviour.