The Unpredictability of Behavior

The phillips curb described an important relationship that was built into economic models for decades, but seemingly didn't apply over much of the last decade. Cromwell's rule is also relevant. Unlike in the physical sciences, in markets and economies, there is very little that absolutely has to happen or definitely can't happen. And if the participants behavior is unpredictable, how can the workings of an economy be modelled? What we're talking about here is the future. There's simply no way to deal with the future that doesn't require the making of assumptions.