ABSTRACT
The assumption of dispositions is the best explanation of certain features of our scientific practice. Elsewhere chapter argues in more detail that theories of laws which do not assume dispositions cannot explain our explanatory practice. The first thing to note is that not all dispositions do the work the carrying over-argument supposes them to do. Dispositions ought to explain how laws that describe the behaviour of systideal circumstances can be tested in, and be explanatorily relevant for less-than-ideal situations. Continuously manifest dispositions (CMDs) allow for partial manifestations. If the partial manifestations are continuously ordered they permit an extrapolation. Galileo's law of free-falling bodies describes the behaviour of objects in a vacuum. His argument assumes these objects to have CMDs. Laws of nature or theories ascribe dispositions to physical systems, they describe how these systems would behave if they were isolated. Causation comes into play when we describe the behaviour of systems that are disturbed and thus fail to be isolated.
