Simulationist was one of the major ranks of the order. Mentats who freed their reasoning from dependence on absolutes, and who could correct for assumptions hidden in another's inferences. The Simulationist saw every human being as a set of behavior patterns ready to be orchestrated.
The Simulationist conceived and proposed in detail alternative futures courses of action, and explanations of events. Economic, political, and military strategy depended heavily on the unfolding of options by Simulationists.
A proper Simulationist could easily offer his master up to ten courses of action, and even infer the dozens of possible consequences of pursuing, altering, combining, or disengaging any of these courses.