A restatement of the case for speed limits

This paper provides a restatement of the case for speed limits. The paper argues that driver speed choice cannot be granted any normative status (i.e. be regarded as optimal from a societal point of view) unless it is “objectively” rational, even if it can be reasonably interpreted as “subjectively” rational. A distinction between “subjective” and “objective” rationality is very rarely made in modern analyses relying on the theory of rational choice, but it makes sense with respect to the choice of speed. Studies that have assessed which impacts of speed drivers consider, whether drivers correctly assess these impacts, and how drivers coordinate their choice of speed with other drivers are reviewed. It is concluded that driver speed choice is not “objectively” rational. It is concluded that the lack of rationality in driver speed choice implies that this choice needs to be regulated by means of speed limits.