Wednesday, May 02, 2007

A Guide to the Argument of Hume's Dialogues, Parts II&III

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Cleanthes has set up an argument in which an analogy between the universe and a machine licenses the inference that, just as the latter has an intelligent cause, so (probably) does the first. Philo's first major move in the Dialogues is to argue that the dissimilarity between the universe and products of human intelligence is so great as to "bar all comparison and inference." In particular, he notes that in applying conclusions of experience to similar cases, every alteration of circumstances introduces a doubt about the legitimacy of the inference, requiring that we gather new information in order to make sure that the new circumstances are not important. There are, however, a vast number of differences between the universe and the products of intelligence that we know. This is particularly true given that the inference requires a move from a part (the products of intelligence) to the whole (the universe). Philo goes even further and denies that one part is a good analogy for another. Even more than this, we know so little about the universe at all, that it seems presumptuous to say something about its origin.

Philo continues piling on points, "somewhat between jest and earnest," when signs of impatience from Cleanthes cause him to stop. Cleanthes responds that someone might say the same with the Copernican system. (Note its reappearance as an example. We will see it again.) Someone inclined to cavil might reject the arguments for it by similar reasoning.

Philo responds that the difference is that we have experience of other planets. We see the moon turn on its center, and likewise Venus. [Venus, of course, does rotate; but Hume is wrong to use it as an example, since the cloud cover for Venus is so thick that it cannot be seen to rotate, and there was no more than a suspicion of its rotation before radio wave experiments in the 1950s penetrated the clouds and showed that Venus does, in fact, rotate. However, by Hume's time the phases of Venus would certainly have been known, and it is likely that he is confusing the two phenomena.] And so one with many other bodies in the solar system. So there are a great many mutually reinforcing analogies in favor of the Copernican system. Indeed, Philo goes further and says that [at the time of the discussion, of course] that they are the only basis for it; Cleanthes would need to have a similar set of strong analogies. Indeed, if we look at Galileo's Dialogue on the systems of the world, we find that a great deal of it is devoted to attacking the distinction between mundane and celestial matter, showing that the earth and the moon were similar in a vast number of details. This allowed one to build the sort of system of analogies that support the Copernican view of the solar system.

Philo ends Part II with a challenge to Cleanthes: "[C]ite your experience and deliver your theory."

Cleanthes is utterly unimpressed by this argument. He opens Part III by noting that the only reason Galileo and others had to devote so much effort to refute the distinction between mundane and celestial matter was that this distinction had so taken hold of people's prejudices that they denied the similarity. The similarity between the works of nature and the works of art, on the other hand, is straightforward and immediate, "self-evident and undeniable." They exhibit "the same matter, a like form": this is precisely what is required for analogies of the strongest sort. Philo's argument is like the argument against motion; the proper reponse to it is not serious argument, which it does not deserve, but "illustrations, examples, and instances."

In order to clarify this point, Cleanthes presents two hypothetical scenarios, the articulate voice and the natural library, in which we would all recognize that a similar inference obviously holds, and which Philo's argument does not have the resources to treat differently.

(1) The Articulate Voice: Suppose, says Cleanthes, that an articulate voice, exceeding what human beings could produce, were to be heard in the clouds, at the same instant, over every nation, and that this voice was heard by every people in their own language and dialect to speak words that were not only meaningful but salutary, worthy of a benevolent being superior to human beings. We would instantly assign to it an intelligent cause on the basis of analogy with human articulate voices, even though the nature of the voice shows clearly that it is very different from any human voice. No one would say that the articulate voice was just accidentally produced by "some whistling in the clouds" rather than from intelligence. Even so in the case of the universe.

(2) The Natural Library: But let's suppose a case that bears an even stronger resemblance to the universe. Suppose two things: (1) that there is a natural, universal, invariable language, common to every human being; and (2) that books are natural objects, perpetuating themselves like plants through reproduction and descent. No one would doubt that such a library is closely analogous to productions of human intelligence, despite its differences.

Cleanthes suggests that in the comparison between these hypothetical scenarios and the universe, the universe is shown to be an even more promising candidate for the effect of intelligence, because there is more evidence of design in an animal than in a book. Either a rational volume is not a proof of a rational cause, or the works of nature have a cause similar to the works of art.

Far from being weakened by Philo's skeptical arguments, Cleanthes says, the inference is strengthened by them. Skeptics are supposed to adhere to inferences that exhibit natural force, even if they are not to assent to them dogmatically. The design inference, however, conveys exactly this natural force. Those who look at the marvelous structure of the eye, and all its contrivance, find it suggesting the idea of a contriver. The conclusion that it has a designer is not something that comes in only at the end of an arduous and tormented line of reasoning. It is suggested immediately, and it is Philo's skeptical reasonings that are better candidates for arduous and tormented reasoning. When we look at male and female, how they correspond in instinct and passion, how they live, we are struck immediately by a teleology, the natural interpretation of which is that nature intends the propagation of the species. The cases mount up easily.

And at this, we reach a curious point in the argument, one that has thrown many people into needless puzzlement. Philo is "a little embarrassed and confounded." He has no ready answer to Cleanthes. But you and I know why this is so -- and, indeed, must be so.

Recall that I suggested that we think of the Dialogues as a game with three players. It had a set of concessions and commitments made by the players that are analogous to rules, and also a set of initial positions marking out the territory the players initially are inclined to defend. The rules are:

(1) Cleanthes and Philo are playing a game of which Demea is not wholly aware, because Cleanthes knows that Philo is half-joking in his support of Demea, whereas Demea thinks that Philo is wholly on his side.
(2) Philo concedes to Cleanthes that skeptics like himself must recognize the natural force of arguments from sense and experience.
(3) Cleanthes has introduced the crucial issue of scientific conclusions, and pointed out that they show that the skeptic can't restrict the natural force of arguments from sense and experience to arguments with conclusions devoted wholly to matters of everyday life.
(4) Demea has made the distinction between arguing for God's existence and arguing that He has certain attributes, and Philo has agreed to it completely.
(5) Cleanthes has presented the particular argument to be discussed. This argument is an argument from sense and experience, and it is in particular an analogical argument from sense and experience.

The initial positions are:

(6) Cleanthes has committed himself entirely to this argument as the one and only argument he can accept.
(7) Demea's immediate reaction to the argument is to protest its 'a posteriori' character.
(8) Philo's immediate reaction to the argument is to protest its analogical character.

Now the notable thing about the opening game is that Cleanthes has won it. And he has to given the rules, i.e., given the concessions already made. He has forced Philo into a position where he cannot move without contradicting his concession in (2). This was essential to Philo's defense of skepticism against Cleanthes: skeptics accept (skeptically, but they do accept) the position on which the argument has the greater natural force. But when we compare the design inference to skeptical doubts about it, the latter are not what have greater natural force. They are less obvious, more difficult to accept, and they do not, unlike the design inference, seem to flow in immediately. Philo has allowed himself to be checkmated.

That is not, of course, the whole story. If it were, we'd have a short and interesting, but hardly striking dialogue. The fact of the matter is that there is more than one game in play. Philo has lost one, and it is because he made the mistake of attacking the analogy. Remember, he insisted that the dissimilarity of the cases was so great that no comparison or inference could be made. This is effectively to deny that the inference can establish the existence of something. But Demea had drawn the distinction between inferring existence and inferring nature, and Philo agreed with it. Philo's mistake was in attacking the first. He is not a position to do so on the principles he has stated. Indeed, Hume's own account of analogy in the Treatise rules out the sort of tactic with which Philo starts, since on that account (1) analogical inferences are based on analogies between cases and (2) analogies cannot be refuted. Philo's attempt to refute the analogy, to deny that it is there to allow the sort of inference Cleanthes wants, is doomed on Humean principles.

So both Philo's principles and Hume's force Philo into confusion; his skeptical attack on Cleanthes's design inference is inconsistent and untenable. But to this point Philo has simply attacked the analogy itself. There is another path open to him, made possible by the distinction between inferring existence and inferring nature. He cannot beat Cleanthes on the ground of the former. But there is a still a game to be played in the latter field. No sooner is Philo confounded than Demea interrupts and performs his most essential function in the dialogue: he begins to play the other game. The game is on again, and Philo has the opportunity play the game from Demea's initial position.

But more of all this in the next post in this series.

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