In the classical approach to economics, conclusions about the way in which economic systems behave are drawn from the analysis of the consequences of assumptions about how the system constituents (individuals, firms, governments, etc.) will behave. Like other nonlinear dynamic systems, the analysis of such systems is difficult, and the detailed behaviors of the systems are highly dependent on the systems' initial conditions and specific design. Small changes in parameters can have very significant effects on the detailed function of the system. Careful scrutiny of the assumptions and initial conditions must be undertaken to ensure that the conclusions are relevant to the real world. Such an approach represents an if-then approach to economics, and has a specific weakness in that it is highly dependent on the creativity of the group generating the assumptions. We describe an alternative, only-if, approach to economics. Adapted from swarm engineering, this approach is a model-independent approach to economics. We demonstrate how, using a particularly simple model, the global economic goal can be described mathematically and used to determine a condition under which the global goal can be reached. We then provide several different types of vendor/consumer agent pairs which satisfy this goal. We also provide an example of a simple system and global goal that is impossible to achieve, demonstrating how this can be determined in a model-independent way.