  Drawing from research on computational models of argumentation (particularly
the Carneades Argumentation System), we explore the graphical representation of
arguments in a dispute; then, comparing two different traditions on the limits
of the justification of decisions, and devising an intermediate, semi-formal,
model, we also show that it can shed light on the theory of dispute resolution.
  We conclude our paper with an observation on the usefulness of highly
constrained reasoning for Online Dispute Resolution systems. Restricting the
search space of arguments exclusively to reasons proposed by the parties
(vetoing the introduction of new arguments by the human or artificial
arbitrator) is the only way to introduce some kind of decidability -- together
with foreseeability -- in the argumentation system.
