Isolation and Folk Physics

There is a huge chasm between the sort of lawful determination that figures in fundamental physics, and the sort of causal determination that figures in the ‘folk physics’ of everyday objects. For example, consider a rock sitting on a desk. In everyday life, we think of the rock as having a fixed stock of dispositions--the disposition to slide on the desk when pushed, to shatter when struck by a sledgehammer, and so on. When a strong interaction comes the rock’s way, the rock’s dispositions determine how it will respond. More generally, we think of the behavior of an ordinary object as being determined by a small set of conditions. The conditions typically specify the object’s dispositions to respond to various sorts of interference, and describe the sorts of interference that the object in fact encounters. Call this the ‘folk model’ (Norton this volume).