Let’s leave that debate aside for the moment, though, and consider why it matters. So what if ID is mechanistic? We can begin our answer to that question by recalling what “mechanism” means in this context. Obviously it has something to do with conceiving of the natural world as a kind of “machine” and of the objects within it, including living things, as lesser “machines” within this larger machine. But that is not the core of the notion, and if all that “mechanism” involved was the view that organisms or other natural objects are in some respects comparable to the things people make insofar as they are composed of intricately arranged parts, etc. there would be no objection to it. As I have repeatedly emphasized, what makes a conception of nature “mechanistic” in the sense objectionable to A-T is that it denies the existence of final causality or teleology as an immanent feature of the natural world. For the mechanist, nothing in the natural order inherently or of its nature “points to” anything else as an end or goal, and nothing is inherently or of its nature “for the sake of” anything else. Accordingly, the mechanist also rejects what the Scholastics called “substantial forms” – immanent natures or essences of things, by virtue of which they have the ends or final causes they do. Mechanists who are also theists hold, accordingly, that any final causality, teleology, essences or natures that exist in the world are extrinsic to it, imposed from outside in a fashion comparable to the way the function of serving as a mousetrap is imposed by an artificer on bits of wood and metal that have no inherent tendency to kill mice specifically. This is the view of thinkers like Newton, Boyle, Paley, and other modern defenders of the “design argument” for the existence of God. By contrast, mechanists who are naturalists or atheists deny that there is any genuine teleology in the natural world at all, of either the intrinsic or extrinsic sort.
Note that this is not my own idiosyncratic definition of what a “mechanistic” conception of nature amounts to. To be sure, the early modern thinkers who put mechanism at the center of Western thought often had other things in mind as well – such as the now-discredited notion that all causality could be reduced to a crude “push-pull” contact model – but it is widely agreed that the core of their position, and the part that has survived to the present day, is the rejection of substantial forms and immanent final causes. Philosopher of science David Hull says that “historically, explanations were designated as mechanistic to indicate that they included no reference to final causes or vital forces. In this weak sense, all present-day scientific explanations are mechanistic” (from the article on “Mechanistic explanation” in The Cambridge Dictionary of Philosophy). Philosopher of religion William Hasker holds that “mechanistic causation and mechanistic explanation are fundamentally nonteleological” and that “it was the expulsion of final causes from physics by Descartes and Galileo that marked what was perhaps the most decisive break between ancient and modern natural science” (The Emergent Self, pp. 63 and 64, emphasis in original). Philosopher of mind Tim Crane writes that “in the seventeenth century… the Aristotelian method of explanation – in terms of final ends and ‘natures’ – was replaced by a mechanical or mechanistic method of explanation… To put it very roughly, we can say that, according to the mechanical world picture, things do what they do not because they are trying to reach their natural place or final end, or because they are obeying the will of God, but, rather, because they are caused to move in certain ways in accordance with the laws of nature” (The Mechanical Mind, Second edition, p. 3). Historian of philosophy Margaret Osler notes that while it is not quite right to exclude God per se from mechanistic explanation (as Crane does), “most seventeenth-century mechanical philosophers rejected immanent final causes – in the sense of the actualization of forms – [and] accepted an idea of finality as imposed on nature from without… With the mechanical reinterpretation of final causes, the idea of individual natures that possess immanent finality was replaced with the idea of nature as a whole which is the product of the divine artificer. Nature became a work of art” (“From Immanent Natures to Nature as Artifice: The Reinterpretation of Final Causes in Seventeenth Century Natural Philosophy,” The Monist vol. 79, no. 3 (July 1996), pp. 389-90).
Now, the A-T philosopher would strongly object to the suggestion that science per se is mechanistic in this sense. The truth is that mechanism is not an empirical discovery at all, but rather a philosophical or methodological preference that has been imposed on modern scientific inquiry by fiat; and the actual empirical findings of modern science are all perfectly compatible with an A-T philosophy of nature. But the authors just quoted are all correct to hold that it is the rejection of final causes and substantial forms that is definitive of mechanism, and that mechanism in this sense is commonly (if mistakenly) regarded as essential to science.
In any event, and as Osler’s remarks indicate, it is in light of this rejection of Aristotelian formal and final causes that the significance of the modern tendency to think of the world as a “machine” – in the sense of an intricate mechanical object comparable to a watch or some other artifact – must be understood. As I have said, to call attention merely to the intricacy and interconnectedness of the parts of organisms and other natural phenomena is by itself unobjectionable. The problem, for A-T, is to think of these parts as having no more inherent or built-in tendency to function together to fulfill a common end than the parts of a watch or a mousetrap do. It is because theistically-inclined mechanists deny such inherent tendencies no less than naturalists do that they focus on questions of probability; for if there is no inherent tendency of the parts of any natural object to function together as they do in the first place, the only way to show that some particular natural object (a biological organ, say) is not susceptible of a naturalistic explanation would seem to be to argue that it is so complex that it is improbable that the parts could have gotten together in just the way they have via purely natural processes. (When A-T philosophers criticize the arguments of Paley or ID theorists for being probabilistic, then, it is not at bottom the appeal to probabilities per se that they object to, but rather the mechanistic conception of nature that motivates such an appeal in this particular context.)
But again, so what if ID or any other theory is mechanistic in this sense? Part of the answer is, naturally, that A-T regards mechanism as false, which is enough reason to reject any view committed to it. But mechanism is a particularly pernicious metaphysical error. Indeed, it is from an A-T point of view arguably the cardinal error of modern thought, from which all the other moral and philosophical pathologies of modern world derive. I noted in an earlier post that it is in mechanism that the modern philosophical tendency toward reductionism is rooted. And I argue at length in The Last Superstition – especially in chapter 5 – that it is also in mechanism that we find the roots of such so-called “traditional” philosophical problems as the mind-body problem, the problem of personal identity, the problem of induction, the problem of giving rational foundations to morality, the problem of epistemological skepticism, and the problem of free will. (At least the latter three problems admittedly predate the modern mechanistic revolution, but were made particularly intractable by it.) Morality and even science itself become unintelligible when one attempts to interpret them in a mechanistic context. As W. T. Stace once wrote, the moderns’ abandonment of final causes was “the greatest revolution in human history, far outweighing in importance any of the political revolutions whose thunder has reverberated through the world,” and in its conception of the natural world as inherently “purposeless, senseless, meaningless” lay “the ruin of moral principles and indeed of all values” (“Man Against Darkness,” The Atlantic (September 1948)). Stace – who was writing from an empiricist rather than an A-T perspective – also recognized that this revolution was purely philosophical and not grounded in any actual empirical scientific discovery. And as I noted in another earlier post, other thinkers outside the A-T orbit (such as Alfred North Whitehead and E. A. Burtt) have also acknowledged the philosophical rather than scientific foundations of the mechanistic revolution, and noted its philosophically problematic implications for the science in whose name mechanists have defended their revolution.
More to the present point, though, is that mechanism is simply incompatible with classical theism – the conception of God historically central both to Christian orthodoxy and to classical philosophical theology, and defended by such thinkers as Athanasius, Augustine, Anselm, Aquinas, and (outside the Christian context) by Maimonides, Avicenna, and others. At the core of classical theism is the doctrine of divine simplicity (discussed in this earlier post) according to which there is in God no composition whatsoever. He is not “made up” of either physical or metaphysical parts, the way everything else that exists is – of form and matter, say, or act and potency, or essence and existence. Rather, he just is “pure act” and subsistent existence. He is not “a being” alongside other beings, but rather Being Itself. Also central to classical theism is the notion that the world of created, contingent things could not continue in existence even for an instant were God not continuously preserving it in being. These doctrines are linked. It is because everything in the created order is composite that it must be “held together” in being by something outside it; and it is because God alone is simple or non-composite that He alone can be that which preserves everything else in being in this way.
Now, for A-T, the Aristotelian distinction between act and potency is crucial to understanding divine simplicity, divine conservation, and the connection between them. The essence of a contingent thing (and thus the contingent thing itself) is merely potential or “in potency” until that essence is actualized through being conjoined to an “act of existence.” Matter is merely potential unless conjoined to and actualized by form. In general, potency cannot exist on its own but only when conjoined to actuality. But only that which is Pure Act can possibly end any regress of “actualizers,” precisely because it is simple and has no parts whose conjunction needs to be actualized. Thus the world of composite things could not exist for an instant unless that which is purely actual and absolutely simple were continually holding it together. (As usual, see The Last Superstition and Aquinas for the full story.)
As I have noted before, the act/potency distinction and the notion of final causality are intimately related: A potency or potential is a potency for some act or actuality, toward which it points as an end; and to have an end is to be in potency towards it. It is no accident, then, that when the moderns abandoned final causality for mechanism, the act/potency distinction was abandoned as well. And it is no accident either that the world came to seem like a “machine,” not only in the sense of a kind of artifact cobbled together from parts having no inherent tendency to function toward a common end, but also in the sense of being the sort of thing that might in principle continue to exist even in the absence of a “machinist.” The doctrine of divine conservation gave way to deism, and deism in turn to atheism.
Keep in mind that for Aristotle and the Scholastic tradition influenced by him, the act/potency distinction is crucial to avoiding the extremes represented by Parmenides and Heraclitus, on either of which science becomes impossible. For Parmenides, change is illusion, and thus so too is the world of our experience, on which any empirical science would need to base its findings. For Heraclitus, permanence is the illusion and there is nothing that can unite the deliverances of experience into an orderly scientific system. Aristotle argued, contra Parmenides, that change is possible because in between being and absolute non-being – the only two categories recognized by Parmenides – there is potency or potentiality. But (contra Heraclitus) permanence is also possible, because within the flux of experience emphasized by Heraclitus there are unchanging forms or essences which matter must take on if it is to be actualized at all. It is because these actualizing forms are universal, common to the myriad individuals which instantiate them, and because they persist even as the individual things come and go, that science is possible. For it is the unchanging and universal forms or natures of things that form the proper subject matter of scientific investigation.
Now, the ancient atomists sought to avoid the Parmenidean and Heraclitean extremes in another way. For them, the world of our experience is indeed the flux Heraclitus said it was, but only because underlying it is a world of unobservable unchanging and indestructible (and in that sense “Parmenidean”) elements – the atoms, interacting according to patterns of efficient causation and devoid of any inherent teleology or final causality. But there is nothing further to be said in explanation of the atoms themselves. Limited as the various atoms are to their particular shapes, sizes, positions in space, etc., they cannot intelligibly be said to be purely actual, simple, or in any other way comparable to (and as “self-explanatory” as) the God of classical theism. Nor, devoid as they are of final causality, do they necessarily point beyond themselves to anything else. Accordingly, they constitute the proverbial “brute fact.” Instead of truly avoiding the Parmenidean and Heraclitean extremes, then, the atomists essentially embraced both of them at once: Like Parmenides, they held that the world of our experience is illusory; in reality there is “nothing but” the atoms. And like Heraclitus, they make the world ultimately unintelligible.
But the atomists were the original mechanists, and their modern successors simply repeat their errors. As I have noted in several earlier posts and have argued at length in The Last Superstition and Aquinas, to reject immanent final and formal causes is to make efficient causality unintelligible as well. For if nothing of its nature “points beyond itself” to anything else, then causes and effects become “loose and separate”; any effect or none might in principle follow upon any cause. This not only paves the way for the paradoxes of Hume, but undermines the possibility of showing how the very fact of efficient causation as such – that is to say, of potency being actualized – presupposes a sustaining, purely actual Uncaused Cause. The metaphysically necessary connection between the world and God is broken; in principle the world could exist and operate just as it does apart from God.
There are of course still questions about how the elements of the world machine (whether we think of these elements as Democritean atoms or in more contemporary terms) come to form more or less complex structures. But the weighing of probabilities vis-à-vis whether this or that structure could have come about through known natural processes can never get you one inch closer to the God of classical theism, because that God has already been ruled out the moment it is conceded that the machine might at least in principle have existed without Him. This remains so even if one’s mechanism is adopted only “for the sake of argument.” Making a case for the God of classical theism on a mechanistic basis even arguendo is like saying “Let’s concede just for the sake of argument that whoever murdered Nicole Brown Simpson and Ron Goldman could not have been a man. Now, let me show you why it is probable, given that assumption, that O. J. Simpson was the killer…” The procedure is absurd, because the opening concession has already eliminated the desired conclusion from the running.
But couldn’t one argue that the elements themselves must have come from God? Yes, but not in a “mechanistic” way. For if one affirms of these elements something like an act/potency composition, then one will indeed get to God, but (since such a composition entails final causality) only because one has implicitly abandoned mechanism. But if one insists on denying of the elements any kind of immanent final causality, then one will thereby implicitly be denying of them any sort of potency that needs to be actualized by something outside them. And in that case, the elements will not be necessarily sustained in being by God. Thus, whatever one appeals to in order to explain them could never be the God of classical theism, but only some idolatrous ersatz. Similarly, the God of classical theism is Being Itself, and nothing could exist – that is to say, have being – even for an instant, even in principle, without participating in Being Itself (whether “participation” is understood in Neo-Platonic terms or in the Aristotelianized terms of Aquinas’s Fourth Way). To “weigh the probabilities” that the elements of a mechanistic universe might themselves have a cause is thus implicitly to rule out the God of classical theism as the cause one is arguing for, since whether a thing participates in Being Itself cannot intelligibly be said to be a matter of probability, any more than whether a geometrical theorem follows from certain axioms is a matter of probability.
As Kant famously held, the “physico-theological” or “design” argument for God’s existence really doesn’t get you to God at all, but only to a grand but finite cosmic architect – something like the Ralph Richardson Supreme Being character from Time Bandits, as I pointed out in a previous post. The same is true of any argument that proceeds, as Paley and his successors have done, by portraying God as a tinkerer who cobbles together a mechanistic universe. And the point, as I cannot repeat too often, is not that such arguments don’t get you all the way to the God of classical theism, but that they get you positively away from the God of classical theism. You can get a god from a machine, but never the God.