If a clock is not made in order to tell the time of the day, I will then admit that final causes are nothing but chimeras, and be content to go by the name of a final-cause-finder — in plain language, fool — to the end of my life.--Voltaire, Final Causes, Philosophical Dictionary, trans. William F. Fleming.
That Voltaire defended the legitimacy of final causes is central to, say, Jonathan Israel's interpretation of the Enlightenment and so presumably reasonably well known. Because of this Israel treats Voltaire as a central member of the more reactionary, moderate Enlightenment. The passage quoted is inexplicable without background knowledge. But one can discern in it what I call the 'Posidonian argument,' which can be traced to Cicero, but was widely discussed in the early modern period (recall, say, here and here). My favorite reconstruction of that argument goes like this:
(I) A necessary condition of the possibility of (an (intended)) successful scientific representation or concrete model of (a region of) nature is that (a region of) nature is orderly;
(II) (A region of) Nature’s hidden order could not be the product of chance [as suggested by Epicureanism] or necessity [as suggested by Spinozism], but only by God;
(III) [It’s possible that] Science produces successful representations and successful concrete models of (a region of) nature.
(IV) ∴ There is a God (of order).
Most versions of the argument treat clocks or planetariums as the kind of things that justify (I). This version does not explicitly introduce final causes, but a natural way to cash out what the God of order does is to be providential. If one does not like that, a traditional way to read the Posidonian argument is something like this:
1.Assume a structural MorphismbetweenDesigned Machine & World
- Designed machine representsnaturesuccessfully
2.Nobodywoulddeny design in Machine –>
3.Nobodywoulddeny design in nature
4.There must be designer
This version of the argument goes from a design that represents nature to a designed nature. And in practice, to say that nature is designed is just to say it is governed by final causes. Much of Voltaire's defense of final causes relies on the Posidonian argument and other more familiar arguments to design.
Voltaire treats Holbach's (1770) version of the attack on final causes as the best source (and mocking Spinoza's version along the way) and quotes at length from Holbach (who had published under the name Mirabaud). It is notable that what Voltaire quotes is not especially original because in the relevant passages Holbach merely recycles the proto-selectionist arguments traditionally attributed (by Aristotle!) to Empedocles.* In the passage quoted by Voltaire, Holbach explicitly quotes (and then aims to answer) the Posidonian argument (some other time more about Holbach's response):
“It will be observed and insisted upon by some that if a statue or a watch were shown to a savage who had never seen them, he would inevitably acknowledge that they were the productions of some intelligent agent, more powerful and ingenious than himself; and hence it will be inferred that we are equally bound to acknowledge that the machine of the universe, that man, that the phenomena of nature, are the productions of an agent, whose intelligence and power are far superior to our own.
So far so good. Here I want to call attention to one feature of Voltaire's response to the criticism of final causes. Because while much of what he says recycles familiar tropes he does say something distinctly modern and, in so doing re-interprets the doctrine of final causes. A representative claim that I have in mind this:
Everything is the result, nearer or more remote, of a general final cause; that everything is the consequence of eternal laws. When the effects are invariably the same in all times and places, and when these uniform effects are independent of the beings to which they attach, then there is visibly a final cause. (§III).
In context, Voltaire is responding the critic who derides the final-cause lover of producing endless just-so stories about local apparent adaptation. Like many early modernist friends of final causes, Voltaire backs off from local final causes (and local providence -- which edge uncomfortably close to miracles --), and defends the respectability of final causes. And he does so by subsuming final causes under general and eternal** laws of nature.
Voltaire here echoes and develops a terse argument by Newton in the General Scholium.*** There are two claims in Voltaire worth noting: first, nature is apparently governed by natural laws; second, when one discerns such invariable laws of nature, one is ipse facto uncovering final causes. That's not silly because one may well think that a law of nature presupposes an all powerful law-giver.
One may think such law-giving talk is just metaphor; one could treat the laws as brute facts and so reject the final cause interpretation of laws of nature. But this violates the PSR, and it's clear that Voltaire assumes that all parties to the dispute presuppose some such principle or explanatory demand.+
*Here's Voltaire quoting Holbach: "Of the power of nature, it is impossible for us to doubt; she produces all the animals that we see by the help of combinations of that matter, which is in incessant action; the adaptation of the parts of these animals is the result of the necessary laws of their nature, and of their combination. When the adaptation ceases, the animal is necessarily destroyed." Compare that with Aristotle's Physics, Book 2, Part 8 (here).
**That they are eternal is worth pondering because it is a denial of creation.
***For just after asserting that it is legitimate to infer final causes, Newton adds that “All that diversity of natural things which we find, suited to different times and places, could arise from nothing but the ideas and will of a Being necessarily existing.” The underlying argument is inductive: the (apparent) functionality of natural things everywhere and always must be ascribed to the mind and volitions of a designer.
+Because the laws are treated as eternal (the brute facticity of) initial conditions are tacitly ruled as a relevant concern.