Tracks and affordances: The sources of a physical ontology

How is meaning assigned to those terms in a theory which are remote from direct observational instantiation? Models and analogies play a role, but close examination of theories in high energy physics shows that the design of experimental apparatus also influences the interpretation of such terms. Certain apparatus favours certain kinds of effects, and this affects the way mathematical theories are interpreted. In particular track producing apparatus becomes involved with theories in which photonic terms are picked out in the theory. A further conceptual constraint is thus introduced. It is argued that this situation favours the interpretation of dispositional properties as affordances rather than as simple dispositions.