Kant vs. Mill in the Brain:
Neural Activity Correlated with Outcome(s) of Moral Decisions
Josh Greene
Princeton
According to the utilitarian tradition in moral philosophy (associated with John Stuart
Mill, among others), a moral decision-maker should simply aim to maximize the
aggregate well-being of the individuals affected by her decision. In contrast,
philosophers in the Kantian tradition maintain that there ought to be moral constraints
on actions reflecting individual rights that cannot be overridden for utilitarian
reasons. We conducted a study in which participants had their brains scanned with
fMRI while responding to challenging moral dilemmas that embody the conflict
between the utilitarian and Kantian perspectives. We examined the neural activity in
a number of brain areas previously determined to be important for making difficult
moral decisions and found that people’s moral decision outcomes (Kantian vs.
utilitarian) correlate with levels of neural activity in different parts of the brain. These
results are a first step toward a neurally based theory of moral personality and support
a model of moral judgment according to which the competition in the brain between
Kantian and utilitarian judgment is not merely a competition between competing
beliefs or impulses, but rather a competition between two competing neural systems.
We speculate that these two systems, one "cognitive" and one "socio-affective," arose
at different points in human evolution and perform different but overlapping
functions.