Realism about Powers
The view about powers that I will be presupposing is a robust realism about powers, in the style of George Molnar (2003).5 It takes powers to be genuine properties of substances (maybe also of other entities, such as electromagnetic fields, but substances are the property-bearers which interest me here). Furthermore, it takes powers and their manifestations (or exercises) not to be reducible to the instantiations of non-power properties or to event-causal sequences. According to this robustly realistic view about powers, powers are properties which are essentially ‘directed at’ certain changes.6 For example, the power of water to dissolve sugar is directed at the dissolution of sugar. It is important to distinguish, in this context, between the process of dissolving and its end-state (i.e., the sugar’s being dissolved). Such a process occurs whenever the manifestation of a power is not instantaneous, and the manifestations of few, if any, powers in nature are instantaneous. A process can begin and ‘get under way’, even though the end-state is never reached, e.g., because the water is deep-frozen by a sudden massive drop in temperature before it has fully dissolved the sugar. While the power is, in a wider sense, directed at both the process and the end-state, the process is primary, since the power is directed at the end-state only insofar as it is reached via a dissolving process. For the water’s power to dissolve sugar is not a power to bring about the end-state in any way whatsoever:7 It is, for instance, not a power to cause the end-state instantaneously as if ‘by magic’. (This does not mean that all the details of the dissolving-process are fixed and that the sugar will always have to be dissolved in one specific way. But not all ways of producing the end-state will count as a manifestation of this power.) I will therefore take the process to be the change that the power is, in the first place, directed at and call it the “characteristic change process (CCP)”.
This process typically involves a sequence of different stages which follow one another in a certain order. Take, for instance, the case of water dissolving a cube of sugar. When we put a cube of sugar into a litre of water, and the powers of the water to dissolve the sugar and of the sugar to be dissolved in water (its water-solubility) are exercised, something like the following sequence of steps is set in motion: The water first softens up the surface of the cube, ‘breaking’ the surface tension, then seeps in and starts to moisten the inside of the cube, progressively breaking up the inside structure etc. (Never mind if this description is somewhat ‘naive’.)
Now, there are two fundamentally different ways of how to think about the nature of this process:8 You could assume that the process just is the sequence of steps, where, on the one hand, the individual steps can be specified independently from the exercise of the powers and are such that they could also occur without their exercise, and, on the other hand, these steps are linked to one another by event-causal connections (such that the preceding step causes the following one). However, on an Aristotelian view of powers, equating the CCP with this event-causal sequence would be fundamentally mistaken. The manifestation of the powers of the sugar and the water will involve such an event-causal sequence, but the CCP is
not "nothing over and above’ this sequence. Only if the different stages, the transitions between these stages, and their temporal order are due to the underlying power(s) being continuously exercised do we have a process of water-dissolving-sugar.
There are several reasons why an Aristotelian account of powers, and a robust realism about powers as irreducible properties, will reject the equation of the CCPs with the event-causal sequence, which we cannot go into here. One of the reasons is the notorious deviant causal chains problem, which we will briefly go into later. But another advantage of the Aristotelian view is that it allows for some flexibility about what will count as CCPs of the same kind. Two processes can, on this view, be of the same kind even if not all the steps in these processes, and their order, are precisely the same (which would seem to follow if one equates the process with a specific event-causal sequence). The crucial thing, on the Aristotelian understanding, is that the sequence of stages is determined by the underlying power, and though the processes must share certain structural features in order to be CCPs of the same kind (as we said earlier, it is not a matter of ‘anything goes’), the details need not be fixed with regard to the individual steps. This feature is attractive, since we want to allow for at least some variation in the details of how the sugar is dissolved by the water.
So, in addition to taking the ‘directedness’ feature of powers seriously, the robust realist I have in mind here also rejects the possibility of a general reduction of the exercise of powers to the causal impact of non-power properties. Furthermore, she rejects both a conceptual reduction of power- ascriptions, as has been proposed by the conditional and causal analyses of power-ascriptions, and an ontological reduction which makes the possession and exercise of such powers out to be ‘nothing over and above’ the possession and causal influence of non-power properties.9
It merits emphasis, though, that this non-reducibility thesis about powers does not by itself say anything about the relation between lower-level (micro-) and higher-level (macro-)levels of reality and their respective causal roles. What it claims is only the non-reduction of powers (and their exercises) to non-power properties. This kind of non-reductionism does not directly rule out Kim’s argument, nor does it directly ensure causal relevance for higher-level powers.