We now turn to Jeffreys’ account of how the non-reductive physicalist account of how greater mental properties emerge from lower physical properties violates central Aristotelian-Thomistic accounts of causality. To say that effects can be greater than their causes violates this account of causality, as we have noted before, but in postulating that the mind arises from matter, this is exactly what emergentism does. The mind is qualitatively superior in perfection to the brain matter with which it is correlated. But it is impossible, from an Aristotelian-Thomistic perspective, for a qualitatively superior pefection to be greater than its efficient cause or causes that go into generating it. The reason for this is because a qualitatively superior effect would be providing the cause something it lacks retroactively. This means that the higher properties came from nothing, which is absurd.
Murphy rejects hylomorphism, however, deeming it of mere antiquarian interest. However, as Jeffreys notes, she provides no evidence in support of this, but merely assumes its truth. For the hylomorphist, the soul is the substantial form of the body. But how or where or why would this contradict modern, atomistic science? She does not explain this at all. Indeed, there is a sense in which this represents a distinctly cognitivist or intelelctualist interpretation of the human mind and its relation to the body, and potential parallels with Merleau-Ponty’s account of embodied cognition, and those similar to it, may be worth investigating.
Commensurate with the abandonment of hylomorphism in modern science was the abnadonment of the Aristotelian-Thomistic understanding of causality. The Newtonian physics which did away with this understanding of causality has itself long-since passed away, and Murphy acknowledges that philosophers have not kept up with science in attempting to offer an accont of causality adequate to it, but she does not explain why a hylomorphic account of causality lacks the requisite adequacy. Just because modern scientists lack an interest in formal and final causality does not mean that they do not exist or lack explanatory relevance, as Jeffreys notes.
He goes on to point out that the greater cannot be brought about by the lesser. This means that the mind, greater in perfection than the matter which supposedly gives rise to it, cannot emerge from it on account of its superior perfectioin. Aquinas goes on to insist that a cause is something which “contributes positively to the being of another.” It is important, as Jeffreys notes, to understand the Thomistic distinction between a cause and a principle. A principle has to do with order among beings whereas a cause has to do with “an influx of being”(Jeffreys, 2004). In particular, the Aristotelian efficient cause is an influx associated with this sort of productivity, as Jeffrey says.The efficient cause is “that by which its action makes something to be, or come into being, either in whole or in part. It answers the question, who or what made this.”
For Aquinas, as Jeffreys notes, “species” is the “lowest unit of classification.” An entity requires a nature in order to exert causality. Nature is defined by Aquinas as “an abiding center of action and being acted on.” This nature, Jeffreys says, determines what an entity can do or have done to it. Human nature, for example, dictates that it cannot live without oxygen. Natures grant entities certain causal powers. Power is defined by Aquinas as the “disposition to a specific form of behavior to something, together with an unspecific reference to the nature or constitution fo the thing or material concerned.”
While this Thomistic account of causality is incompatible with Murphy’s non-reductive physicalism, this does not mean that there are no such thing as emergent entities or properties. Some things and processes are not reducible to their parts. However, for the Thomist, Jeffreys notes, the things that are produced cannot exceed in quality the things which produce it. Thus, non-reductive physicalism cannot be true. Physical matter simply does not possess the ability to give rise to mental properties, intimately bound up with one another though they may be (and indeed, are).
It is possible, however, to accept the account of causality advocated by Carl Hempel or Ernest Nagel, according to whom causality is bound up with nomic “regularity, spatial contiguity, temporality, and asymmetry” rather than adopting a Thomistic understanding of efficient causality which views it in terms of productivity. On this account, it becomes unnecessary to insist that the greater in perfection cannot be produced by the lesser in perfection.
Of course, she cannot adopt a Humean or Russellian skepticism of causality, since she writes about God acting on a quantum level. Only someone sympathetic with occasionalism would adopt such a thing. Nor is it clear that she can adopt the aforementioned nomological conception of causality, as Jeffreys notes. She ends up disliking the idea of a law of nature, preferring instead a sort of regularity which only appears as a law. Indeed, she appears agnostic about the existence of a law of nature.
Jeffreys, Derek (2004). The Soul is Alive and Well:
Non-reductive Physicalism and Emergent Mental Properties. Theology and Science, Vol 2, No. 2, 2004 (dx.doi.org/10.1080/1474670042000261105 )