Discovering and studying emergent phenomena are among the most important activities in social research. Replicating this phenomenon in "the lab" using simulation is an important tool for understanding it. Multi-Agent Systems (MAS) provide a suitable framework for such simulation. When such simulations are used to represent social processes there are necessarily indeterministic and arbitrary aspects, which are typically represented as either random choices (or numbers) or constants chosen by the programmer. Each such `choice' means that the simulation takes one of the possible `trajectories'. The implicit theory that a simulation represents is precisely not in the individual choices but rather in the `envelope' of possible trajectories