A stit Logic Analysis of Morally Lucky and Legally Lucky Action Outcomes

Moral luck is the phenomenon that agents are not always held accountable
for performance of a choice that under normal circumstances is likely to result in a
state that is considered bad, but where due to some unexpected interaction the bad
outcome does not obtain. We can also speak of ‘moral misfortune’ in the mirror
situation where an agent chooses the good thing but the outcome is bad. This paper
studies formalizations of moral and legal luck (and moral and legal misfortune).
The three ingredients essential to modelling luck of these two different kinds are (1)
indeterminacy of action effects, (2) determination on the part of the acting agent,
(3) the possibility of evaluation of acts and/or their outcomes relative to a normative
moral or legal code. The first, indeterminacy of action, is modelled by extending stit
logic by allowing choices to have a probabilistic effect. The second, deliberateness
of action, is modelled by (a) endowing stit operators with the possibility to specify a
lower bound on the change of success, and (b) by introducing the notion of attempt
as a maximisation of the probability of success. The third, evaluation relative to a
moral or legal code, is modelled using Anderson’s reduction of normative truth to
logical truth. The conclusion will be that the problems embodied by the phenomenon
of moral luck may be introduced by confusing it with legal luck. Formalizations of
both forms are given.