5.1 Beyond simple dispositions

Most examples of dispositions in the previous chapter were those, like fragility, solubility, radioactive instability, whose effects (if manifested) are changes or events of some kind. If a glass exercises its fragility, it breaks. If salt shows its solubility, it dissolves. The manifestation of radioactive instability would be a decay event detected with a Geiger counter. Physicists want to know not merely that these events occur, but also how the dispositions themselves may change after the manifestation event. In the cases here, the fragility of the parts or the stability of the nuclei may change as a result of those manifestation events, and it is an important part of physics to describe the new (changed) dispositions as accurately as possible. Such descriptions are part of more comprehensive dynamical theories, as distinct from descriptive accounts of events.

Sometimes, new dispositions may be ascribable after an event that could not have been ascribed before the event. The fragments of a broken glass may be able to refract light in a way that the intact glass could not. The dissolved salt may be able to pass through a membrane, in contrast to the disposition of the initial salt crystals. The fragments arising from a nuclear decay may decay by emitting electrons in a way the parent nucleus could not.

It often appears that new dispositions may be ascribed as the result of a prior disposition’s operation. It then appears that new dispositions come into existence as the manifestation of previous dispositions. Since now one disposition leads to another, some philosophical analysis is called for.

The existence of some of these new dispositions may be successfully explained as the rearrangement of the internal structures of the objects under discussion, when these are composite objects. The refraction by pieces of broken glass, in contrast to the original smooth glass, has an obvious explanation in terms of the shapes of the new fragments. Salt’s diffusion through a membrane, once dissolved, is presumably because of the greater mobility of salt ions in solution compared with the crystal form.

Science is largely successful in explaining such dynamical evolutions of empirical dispositions of natural objects. It bases the explanations in terms of changes to their structural shapes and arrangements of their parts along with the fixed underlying dispositions or propensities of these parts. It is from the dispositions of these parts that, according to the structure, all their observed dispositions and causal properties may be explained.

The existence of new dispositions by rearrangement of the parts of an object is non-controversial within existing philosophical frameworks. It appears that typical philosophical analyses of an aggregate can readily accommodate the way its derivative dispositions are explained in terms of recombinations of the dispositions of its parts.

However, not all dynamical changes of dispositions occur by rearrangements of parts. Those that are not rearrangements are what I call derivative dispositions. There are some cases, to be listed below, where new dispositions come into existence without there being any known parts whose rearrangement could explain the changes. The next section gives some examples from physics and psychology of what appear to be such derivative dispositions. This is followed by an analysis of how these might work.