  Sub-grid modelling methods can be contrasted with another kind of parallel multiscale model where the sub-grid algorithms are more theoretically principled, but are motivated by a theory at a different level of description. In the example of the simulation of bulk matter mentioned above, for example, the algorithm driving the smaller level of description is not built by the seat-of-the-pants. The algorithm driving the smaller level is actually more theoretically principled than the higher level in the sense that the physics is more fundamental: quantum mechanics or molecular dynamics vs. continuum mechanics. These kinds of multiscale models, in other words, cobble together the resources of theories at different levels of description. So they provide for interesting examples that provoke our thinking about intertheoretic relationships, and that challenge the widely-held view that an inconsistent set of laws can have no models. 