  In this essay, I argue that explicit ethical machines, whose moral principles
are inferred through a bottom-up approach, are unable to replicate human-like
moral reasoning and cannot be considered moral agents. By utilizing Alan
Turing's theory of computation, I demonstrate that moral reasoning is
computationally intractable by these machines due to the halting problem. I
address the frontiers of machine ethics by formalizing moral problems into
'algorithmic moral questions' and by exploring moral psychology's dual-process
model. While the nature of Turing Machines theoretically allows artificial
agents to engage in recursive moral reasoning, critical limitations are
introduced by the halting problem, which states that it is impossible to
predict with certainty whether a computational process will halt. A thought
experiment involving a military drone illustrates this issue, showing that an
artificial agent might fail to decide between actions due to the halting
problem, which limits the agent's ability to make decisions in all instances,
undermining its moral agency.
