Substantive rationality requires a decision-maker to be a utility maxi
mizer; under this paradigm, the decision is paramount, and not depende
nt on the computational process used to obtain it. Procedural rational
ity is dependent on the method used to make the decision; reasonablene
ss of the procedure is paramount. Well-formed problems are amenable to
substantive rationality; ill-formed problems are not, but are amenabl
e to procedural rationality. To qualify as being procedurally rational
, a methodology must possess a sound epistemological basis, it must be
amenable to a formal design synthesis procedure, and it must be consi
stent with substantive rationality. Epistemic utility theory forms the
basis of a decision rule that is procedurally rational. This theory a
dapts to decision-making in the context of control theory, and leads t
o a specific design procedure that may be applied to single- and multi
ple-agent ill-formed control problems.