 The second basic approach is to focus on successive refinements of the model while keeping the initial data fixed (e.g., Wimsatt 1987). The idea here is that if a model is faithful in reproducing the behavior of the target system, refining the model will produce an even better fit with the target system’s behavior. This is to say that if a model is faithful, successive improvements will lead to its behavior monotonically converging to the target system’s behavior. Again, the import of the faithful model assumption is that if one were to plot the trajectory of the target system in an appropriate state space, the model trajectory in the same state space would monotonically become more like the system trajectory as the model is made more realistic. 