We extend universal moral grammar theory (UMGT) with nonmonotonic
logic. Our experiment shows that such revision is
necessary as it allows to account for the effects of alleviations
and aggravations in moral reasoning. Our new theory updates
UMGT from classical to non-monotonic logic, which reflects
the incompleteness of information and uncertainty in actual
human reasoning. In addition, it provides an explanation of
the paradoxical findings in the moral dilemma of the Trolley
problem and the Knobe effect