  We argue that the attempt to build morality into machines is subject to what
we call the Interpretation problem, whereby any rule we give the machine is
open to infinite interpretation in ways that we might morally disapprove of,
and that the interpretation problem in Artificial Intelligence is an
illustration of Wittgenstein's general claim that no rule can contain the
criteria for its own application. Using games as an example, we attempt to
define the structure of normative spaces and argue that any rule-following
within a normative space is guided by values that are external to that space
and which cannot themselves be represented as rules. In light of this problem,
we analyse the types of mistakes an artificial moral agent could make and we
make suggestions about how to build morality into machines by getting them to
interpret the rules we give in accordance with these external values, through
explicit moral reasoning and the presence of structured values, the adjustment
of causal power assigned to the agent and interaction with human agents, such
that the machine develops a virtuous character and the impact of the
interpretation problem is minimised.
