The harmony of nature

Aquinas takes the harmony of nature not to need much argument. But in the eighteenth and nineteenth centuries, as the argument from design was increasingly developed by so-called natural theolo­gians, a great deal of evidence was assembled for the harmony of nature.

Look round the world: Contemplate the whole and every part of it: You will find it to be nothing but one great machine, subdivided into an infinite number of lesser machines, which again admit of subdivisions to a degree beyond what human faculties can trace or explain. All these various machines, and even their most minute parts, are adjusted to each other with an accuracy which ravishes into admiration all men who have ever contemplated them. The curious adapt­ing of means to ends, throughout all nature, resembles exactly, though it much exceeds, the productions of human design, thought, wisdom, and intelligence.

Hume didn't literally mean that the world was composed of machines; to say that would be begging the question, since a machine is by def­inition something made to a design. Presumably what he had in mind was that, like an enormously intricate watch—but to a very much greater degree—the world was made of parts that fitted together and functioned as if each were made to work with the others. One of the most obvious examples of this, which the great nineteenth-century natural theologian William Paley made famous, is in the mutual adap­tation of parts that we see in an animal organ like the eye.

Its coats and humors, constructed as the lenses of a telescope are constructed, for the refraction of rays of light to a point, which forms the proper action of the organ; the provision in its muscular tendons for turning its pupil to the object, similar to that which is given the telescope by screws, and upon which power of direction in the eye the exercise of its office as an optical instrument depends;...

There seem to me to be two lines of thought running together here. One is the general notion that we can find in nature many things, like eyes, that have obvious functions, and whose parts are very finely adapted to making them work. These things are not made by human or other animal designers. But they are, in this respect, strik­ingly like things such as telescopes, which were made by designers. Call this “the mutual adaptation of the parts of the world.” That is the point of insisting on the “preparation of means so mani­fest in their design.” (From now on, I'll feel free to use “harmony” as shorthand for this sort of mutual adaptation of parts.)

The other, more specific line of thought is that many things in the universe—eyes, among them—appear to have been especially designed to be beneficial, that is, to be useful to us. Cleanthes, in the passage I cited, was only making the first argument; he was not addressing the issue of whether the harmony in nature suggested a creative intelligence who was favorably disposed toward us. But, in fact, the ways in which the world contains things that are useful to human beings might be thought to be an instance of the mutual adaptation of the parts of the world. Not only do eyes work to allow us to see, and thus to move about in the world, but the existence of plants that we can eat, materials from which we can make clothing and housing, and the like is also, perhaps, a mutual adaptation of parts.

So the claim seems to be that there is a significant similarity between the ways in which parts of a watch or a telescope fit together and the ways in which parts of the eye, and parts of the world more generally, fit together.

Paley's discussion of the eye does not seem very helpful here. If you are going to have an eye that works, its parts must be in some sense mutually adapted. So, perhaps the thought is that a universe without mutual adaptation would contain nothing with a function. For it is only by reference to its function as an instrument of vision that we can say that the parts of the eye are mutually adapted. But then it seems wrong to say that the parts of the universe as a whole are mutually adapted, since most things in the universe don't appear to have a function like the eye's. That is, Paley's argument seems like an argument for the view not that the universe was made but that some of the things in it—the ones well adapted for their functions— were. And it is, of course, open to the objection that Darwin's the­ory of evolution provides an equally compelling explanation of how parts well adapted for their functions in organisms could come into being without a designer.

Cleanthes' argument, on the other hand, is about all of nature. It is not open to the Darwinian response. So the widespread view that Darwin's theory of evolution refutes the argument from design just seems wrong.

This may seem evidently true. But is this claim as clear as it at first appears? After all, what would a universe look like that con­tained no order? Or, at least, so little order that it would be reason­able to think it was not the result of intelligent design? I think it is very hard to say.

Perhaps there could be a universe with literally no regularities, a possible world where there were no patterns at all. I find it hard to see what this would mean, but let me concede the possibility for the purposes of argument. Still, there certainly could not be a universe where we noticed that there were no patterns. For noticing is a causal process, which depends on regularities that connect how things seem to us with how they are. No patterns, no noticing. And so, putting it the other way round, if there is noticing, there are pat­terns. As we saw in Chapter 2, we could not come to know anything at all about the universe if we did not have reliable senses, least of all how orderly it was. From this it follows that any creature in any possible world that could explore the a posteriori question whether the universe was orderly would be bound to discover some order. Noticing this, a skeptic could respond to Cleanthes like this:

Let's call the possible worlds where there are people and there's enough order for people to notice it the “noticeably orderly worlds.” Surely there could be a noticeably orderly world where the order was not the product of God's design. But then it follows that the mere fact that we notice order doesn't mean that we're in a possible world where God exists. So, contrary to the second premise of the argument from design, a creative intelligence is not necessary.

Let's call this “the argument against the necessity of design.”

You might think that Cleanthes should reply to this argument that there couldn’t really be a noticeably orderly world that wasn't produced by a creative intelligence.

If he insists that none of the noticeably orderly worlds is Godless, then he has made the wrong argument. For his argument proceeds from the premise that the universe is harmonious. But now he is saying that any order at all, even a disharmonious order, is evidence for the existence of God. This is an interesting view, but it is much less plausible than the argument from design. For it requires some argument, I think, to establish that an amount of order just suffi­cient for humans to notice would establish the existence of an intel­ligent creator.

So suppose he concedes, on the other horn of the dilemma, that some of the noticeably orderly worlds are Godless. Then he has to offer some special reason for thinking that the actual world displays a degree of order sufficient to warrant belief in a designer. We already have a name for that amount of order, of course: it is “har­mony.” So now the question is: How much order does there have to be for the universe to be said to be harmonious?

This seems to me a harder question that either Cleanthes or Aquinas acknowledges in the passages we have been discussing. After all, though there is plenty of evidence of things working together in the world, there is also plenty of evidence of things working against each other. Aristotle, who rejected the form of the argument from design that his teacher Plato had developed, observed that the earlier philosopher Empedocles

was aware that the stark opposites to the goods are likewise present in nature, not only order and beauty, but also disorder and the ugly, and more evils than goods, more vile things than noble; therefore he introduced both love and strife, each to account for one of the two opposites.

Most eyes work, more or less, it is true; but many people are near­sighted, farsighted, or blind.

Without answers to these questions, we do not really understand the first premise of the argument from design. And if we do not understand it, how can we be sure that it is true?

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