Abstract
It is argued that sufficient is known about the broad causal factors underlying crashes to prompt action. The challenge for society has been and remains whether we are prepared to take action to reduce casualties. There are key philosophical arguments and psychological processes at the heart of this debate. Given that these arguments and these psychological processes operate as the gatekeepers to action, it is argued that they merit more attention than they have received. The paper provides an examination of the "harm principle", which has been employed to limit paternalistic interventions. More generally, the perceived legitimacy of intervention is examined, and the specific case of speeding is considered.