  Decision making can be difficult when there are many actors (or agents) who
may be coordinating or competing to achieve their various ideas of the optimum
outcome. Here I present a simple decision making model with an explicitly
hierarchical binary-tree structure, and evaluate how this might cooperate to
take actions that match its various evaluations of the uncertain state of the
world. Key features of agent behaviour are (a) the separation of its decision
making process into three distinct steps: observation, judgement, and action;
and (b) the evolution of coordination by the sharing of judgements.
