St. Thomas Aquinas does not often find kindred spirits among contemporary analytic philosophers. Among those not particularly sympathetic is the imminent Richard Swinburne. It is well known among his readers that Swinburne carries no brief for classical theism, the concept of God attributed to St. Thomas. What is regrettable about this situation is how Swinburne stands athwart or ignores Aquinas where the Angelic Doctor could potentially be helpful. In this post, I try to offer a case in point.
In chapter five of The Existence of God (Rev ed. pp.70-89). Swinburne goes through a treatise on complete explanation. The primary thrust of this idea is there are theories that, if you were to try going beyond it, would not yield any further explanatory power. Swinburne distinguishes between full, complete, ultimate, and absolute explanations.
A full explanation explains by itself why something happened, regardless of whether there is any further explanation of it. X can be a full explanation of Y whether or not there is an explanation of X. If we had to pursue explanations all the way down, we would never be able to explain anything without appeal to the origin of the universe. Full explanations can get us quite far. Far enough to make good arguments about causes and explanations.
A complete explanation is a special kind of full explanation. It takes into account other factors in an occurrence for which there is no explanation for their existence or operation in terms of other factors operative at the time of their existence. A complete explanation of X by Y would, it seems to me, take into account factors of Y.
An ultimate explanation is a special kind of complete explanation. This type of explanation is where we pursue explanations and factors of an occurrence all the way down until we get to ultimate brute facts. If X explains Y, and W explains X, and so forth we eventually hit a brute fact for which there is no further explanation. Perhaps this is V. V explains W, W explains X, and X explains Y. But V is a brute fact.
An absolute explanation is one where brute facts are not cited; all factors in an occurrence are either self-explanatory or logically necessary. Swinburne does not think there are absolute explanations of logically contingent phenomena, nothing explains itself (76). For Swinburne, arguments for the existence of God are arguments to a complete explanation of phenomena.
The issue Swinburne has is that he believes Aquinas is arguing on a priori grounds that any full explanation has a complete explanation. Swinburne thinks that in some cases it is probable that phenomena with full explanations have complete explanations. In the appendix to chapter five, Swinburne takes up some thoughts on causation from Scotus and Aquinas.
When looking at Aquinas’ causal reasoning, Swinburne uses the common example of the train cars in discussions of essentially ordered causes. There is an infinitely long train, each car pulls the other one. For Swinburne, the car X pulling car Y is a full explanation of Y’s movement along the track. There is no need to appeal to anything further in explaining the motion of Y, even if there are other things going on somewhere. Earlier, Swinburne referred to one form of opposition to this idea as the “completist fallacy.” He believes Hume commits this in Dialogues when Philo raises the “who designed the designer” rebuttal to the design argument. Swinburne thinks Hume is wrong because, presumably, the Designer is a full explanation of the order of the world. Perhaps it is not a complete explanation, but it is full or at least sufficient to explain the phenomena in question such that no other theory or hypothesis would yield greater explanatory power. Swinburne thinks Aquinas commits the same fallacy as Hume because Aquinas believes that there is no explanation or cause of Y unless there is an engine (‘first cause’ in metaphysical terminology) that moves the entire train. For Aquinas, X is not a full explanation for the movement of Y.
Swinburne is at least correct in that Aquinas would agree that X is not a full explanation of Y. But Aquinas would hold that X certainly had a causal role in this series, just not an essential causal role. X would not be sufficient to explain the movement of Y, for X, in this case, does not actually have any causal power on its own to effect movement. X is only an accidental cause of Y, and ultimately cannot fully explain the movement. Further, X only explains Y insofar as they are connected. But X could be removed. Y would then be connected to W, and still in motion. The question would remain; what then accounts for or sufficiently explains the motion of Y? If X could in principle be removed, and Y connected to W with the motion of Y continuing, then X cannot be a full explanation of Y. There is not enough explanatory power in isolating X to explain the movement of Y, given that we know in this example that X does not have motive power of its own. X must get its motive power from another source, as is the case for Y.
Swinburne refers to Aquinas as seeking an a priori argument for his position. Swinburne finds there is no argument on these grounds against an infinite regress of essentially ordered causes. From my perspective, it seems Swinburne means there is nothing bound up in the terms at issue, viz. essential cause, accidental cause, effect, and so forth that preclude one from holding without contradiction there could be an infinite regress. That is, there is nothing incoherent in supposing there could be an infinitely long train in which each car simultaneously moves another. It is problematic to attribute a priori reasoning to Aquinas since he believed we got our knowledge of things and their causes from direct interaction with the world. Leaving this aside, for now, Swinburne may be right as far as it is stated. There may be nothing a priori incoherent or contradictory in making this assertion. But perhaps this could be challenged, given what we know about train cars, motion, and so forth. Maybe even as bound up in their terms or definitions. For example, we know train cars have no motive power of their own. We know that things without motive power cannot move themselves. We know that no matter how many train cars there might be, perhaps an infinite number, there must be something with motive power that is moving them if they are in fact moving. When Swinburne says “each truck [train car] by its own motion simultaneously makes the other truck move…” (89) I think the major disagreement here is the reference to “…by its own motion…”. Aquinas would not agree that the train cars (again, just using this as the example of essentially ordered versus accidentally ordered causes) have their own motion. Since train cars do not have their own motion, they must get it from another. And thus, it is not possible that the train cars could do anything by their own motion. X does not have its own motion, per se. Neither does W. Y is not moved by the motion of X per se, because X does not have any motion or motive power per se. It is only in virtue of an engine that any motion is conveyed or available to X, which then passes through X to Y. At best, X is only a partial explanation of the movement of Y. Only as an accidental cause of the motion of Y is X an explanation of Y’s movement.
The reason why I think adopting Aquinas’ reasoning could help is this. Swinburne refers to causal powers of bodies when comparing ways of scientific thinking (42-44). He argues that the ‘ancient’ way of thinking that bodies have powers and liabilities (what Aquinas might say are act and potency) are a better way of thinking about scientific explanation. Swinburne rightly seizes on the modern move to think of laws and events independently of bodies (or substances). I think this breakdown helps Swinburne’s account of agent causation, which is that such causation is not reducible to events or laws, and is (for Swinburne) not reducible to ‘bodies’ as such since agent causation is not species of liability (i.e. potentiality) of a body.
If he recognizes that bodies (substances) have powers and liabilities (e.g. they are combinations in some way of act and potency), then it follows that some bodies do not have within themselves the powers to do certain things. The stone does not have within itself the power of locomotion. Neither does the stick. It is the hand of the person moving the stick, which moves the stone. The stone has within itself the power or liability to be moved. So does the stick. But they cannot bring these about without the simultaneous action of the hand of the person (agent) moving the stick. It is not possible that the stick is a full explanation of the movement of the stone. But this is what Swinburne seems to be claiming in his critique of Aquinas. He seems to be saying that the motion of the stick, which does not have in itself the power to move anything based on what it means to be a stick, is all that we need to sufficiently explain the movement of the stone. On this point, I believe Aquinas would disagree. And I think Aquinas has a much stronger argument. Swinburne’s approach on this point seems to cut off the causal explanation process right when it starts to get interesting. This could be due to the very scientifically focused methodology, where the arguments start to spill over into metaphysics with reasoning tools that are made for not wholly adequate for that application. If he were to take Aquinas’ notion of essentially ordered causes, Swinburne would have a more robust account of explanation, which would help his overall case. It would represent great consistency, especially with the appeal to the natural scientific reasoning about bodies that he referenced earlier.