Aspects of the Theory of Moral Cognition: Investigating Intuitive Knowledge of the Prohibition of Intentional Battery and the Principle of Double Effect

Where do our moral intuitions come from? Are they innate? Does the brain contain a module specialized for moral judgment? Does the human genetic program contain instructions for the acquisition of a sense of justice or moral sense? Questions like these have been asked in one form or another for centuries. In this paper we take them up again, with the aim of clarifying them and developing a specific proposal for how they can be empirically investigated. The paper presents data from six trolley problem studies of over five hundred individuals, including one group of Chinese adults and one group of American children, which suggest that both adults and children ages 8-12 rely on intuitive knowledge of moral principles, including the prohibition of intentional battery and the principle of double effect, to determine the permissibility of actions that require harming one individual in order to prevent harm to others. Significantly, the knowledge in question appears to be merely tacit: when asked to explain or justify their judgments, subjects were consistently incapable of articulating the operative principles on which their judgments appear to have been based. We explain these findings with reference to an analogy to human linguistic competence. Just as normal persons are typically unaware of the principles guiding their linguistic intuitions, so too are they often unaware of the principles guiding their moral intuitions. These studies pave the way for future research by raising the possibility that specific poverty of the stimulus arguments can be formulated in the moral domain. Differences between our approach to moral cognition and those of Piaget (1932), Kohlberg (1981), and Greene et al. (2001) are also discussed.