Powers-Based and Neo-Humean Accounts Compatible on the Level of Characterisation

If neo-Humean views are treated merely as characterisations of causation then they do not significantly contradict powers-based accounts, because they neither try to compete on the level of explanation nor do they disagree on the level of characterisation. Indeed, neo-Humean views don’t significantly disagree with each other either. Let me illustrate these points using a rough sketch of the standard view and which I will elaborate on in the next chapter. According to the standard view, causation involves the production of changes through interactions between powerful particulars. The characteristics of the changes produced are determined partly by the influence being exerted between the objects in virtue of their so-called active powers (their ability to influence other objects), and partly by their respective passive powers (ability to change in some way in response to the exertion of influence of an active power). The idea is that, whenever an object possessing certain active powers interacts in a certain way with another object possessing certain passive powers, the outcome is always the same. Whenever you throw the same kind of brick in the same kind of way at a window of a certain type, the window will break. On this view a cause C is really a determinate kind of interaction between two determinate kinds of powerful particulars and the effect E is the outcome of that interaction. The core idea of this view has been expressed by Mario Bunge (1979: 47) in the following way:

If C happens, then (and only then) E is always produced by it.

Note that I have yet to explain the nature of‘production’ (see subsequent chapters), but this is enough for our present purposes.

The interesting point about the standard view is that it entails that causation will exhibit all the salient features pointed out by the reductive views. It entails that whenever C happens E will follow, just as the regularity view predicts, but offers a further analysis of C that incorporates the distinction between rhe sufficient and necessary conditions drawn in the conditional analysis; C in Bunge’s characterisation corresponds to the nexus of C and S in the conditional analysis, i.e. of the action of the Agent and the passive object or state of affairs upon which the Agent acts. Note that it provides criteria to distinguish between C (something ‘active’) and S (something ‘passive’). It also entails that C will increase the probability of the occurrence of E, although on necessitarian accounts we have to understand the uncertainty implied in ‘probably’ as due to our uncertain knowledge of the details of any particular instance c of the kind C.

One of the nicest examples of a dependency between the anti-reductive and reductive views is between the standard view and interventionist accounts. The standard view entails that intervention is an excellent method to identify causal connections. Given that it is true that whenever C happens, and only then, E invariably follows, it follows that when C occurs E will appear and when C is removed E will be removed, and that C is the only thing that can do that. So, all you have to do to find out the cause to E is to manipulate anything that could conceivably be the proximate cause and whenever the presence or absence of anything reliably makes E appear or go away, you will have found the cause. Conversely, assume the falsity of the standard view, and it entails that intervention is an unreliable method to identify causal connections. Suppose C only sporadically produces E, and is not the only thing that produces E, then it follows that intervention will be an unreliable method to identify causal connections, and it will be less reliable to the same degree as

Potcers-Based vs. Neo-Humean Approaches 25 the production is less reliable. At least, in the absence of an explanation of why causes reliably bring effects about, the interventionist account doesn’t have an explanation as to why manipulation of causes makes the effect appear/disappear.

Galileo Galilei is nowadays often portrayed as an early interventionist. To be more precise, it is argued not only that Galileo developed the scientific method—the use of manipulative experimentation to identify causal connections—but developed a radically new concept of causation (Ducheyne 2006; Ducheyne & Weber 2007). Like William Wallace (1988), I disagree with this reading of Galileo. To my mind he is much more reasonably understood as drawing out an epistemic consequence from the standard view of his time, notably that whenever objects of a certain kind interact in a certain way the outcome is always the same. Now, as Wallace points out, Galileo’s own texts are probably inconclusive as evidence of his actual views on this particular matter, and I am not really concerned with proving Galileo right or wrong. The main point is that if we assume the standard view, it will work as an explanation of why intervention works, and it does not really contradict interventionist accounts considered as attempts to characterise causation. Contrariwise, if we assume the standard view to be wrong, no explanation exists of why the world should exhibit the features pointed out by the neo-Humean views. Indeed, it is often assumed that these features are brute facts.

It is also interesting to note that the reductive views are compatible with each other. It can be simultaneously true that causation appears to us as a regularity (albeit a triadic rather than a dyadic one), as probabilistic, as counterfactual, and as interventionist. We can however debate which of these characterisations offers the most reliable way to recognise causal connections, but that is surely an epistemic issue.

It seems to me that if proponents of neo-Humean accounts are going to reject powers-based accounts it is not because of any disagreement about how causation appears to us in experience. And it will not be based on disagreement on the level of explanation, because neo-Humean accounts do not offer explanation. The disagreement will revolve around a meta-philosophical disagreement about the proper method of philosophy in general. In other words, the disagreement will revolve around the question of whether or not philosophy (and science) is confined to merely characterise reality as it appears to us in experience.

Of course, there is the issue of necessity, which has been a disagreement between causal realists and neo-Humeans, but more recently also internally between causal realists. But how are we to understand that disagreement? Usually it is understood in terms of neo-Humeans insisting that there is no substantial connection between entities in the world (everything is loose and separate) while causal realists insist there is a substantial connection while perhaps disagreeing on whether thatconnection amounts to necessitation or not-quite necessitation. However, there is a vast difference between accepting neo-Humean accounts as simply empirically adequate descriptions of a world that may or may not contain substantial causal connections, or accepting them on a more ontological level as correct accounts of a world in which substantial connections are missing. As I have explained, the epistemic reading of neo-Humean accounts makes them compatible with the standard view, and therefore not of much interest to the subject of this book. From now on, unless otherwise specified, I will predominantly be discussing the ontological understanding of neo-Humean accounts, or, really of neo-Humean metaphysics, the doctrine that there are no substantial connections between the entities of our world.

The clash between the descriptive and explanatory approach is nowhere as clear as in Hume’s discussion of causation. Indeed, where most contemporary neo-Humeans don’t really bother to explicitly motivate their aversion to metaphysical speculation—that is just taken to be the default stance—Hume is very explicit on that point. I gather that is why neo-Humeans often appeal to Hume for support for their position. However, it does not seem to me that Hume offers much to support neo-Humean metaphysics.