Part I introduces the characters, Cleanthes, Demea, and Philo. The discussion when the dialogue has opened has turned to religious education, and Demea has claimed that the mind needs to be brought into submission to religious principles by emphasis on the uncertainties, obscurities, and confusions that plague all forms of human reason. Philo praises this idea, saying that if this recommendation is cultivated, we would learn not to give much credit to frail reason on topics so sublime and difficult as theological ones. Demea takes this straightforwardly as praise; Cleanthes sees at once that Philo is engaging in "some raillery or artificial malice". Much of the rest of the Dialogues is an expansion of this: Demea takes Philo naively, Cleanthes sees Philo is engaging in a bit of mockery. But Cleanthes and Philo keep up the game throughout (which is important), and Cleanthes replies to Philo's speech that he is proposing to ground religion on philosophical skepticism, and jokes that we'll see how deep Philo's skepticism runs when the company breaks up and Philo goes out the door rather than window and assumes throughout that gravity will hold his body to the ground. Nature overrules the artificial principles of the Skeptics, just as it overrules the artificial principles of philosophical schools like the Stoics.
Philo concedes that this is so, and the fact that he does so is extremely important for the course of the argument, so keep it in mind. However, he notes that while the principles of the Stoics may have been artificial, impossible to maintain outside of the highest flights of philosophical contemplation, nonetheless, by accustoming themselves to these principles in one part of their life (namely, philosophical reasoning), they developed a disposition that carries over into other parts of life -- only partially and imperfectly, it is true, but which allowed the Stoic school to produce some outstanding examples of virtue. Likewise, says Philo, when someone accustoms himself to thinking about the limits and failings of human reason, something of this disposition carries over into other aspects of life. The Skeptic's position is simply that in an "abstract view" reason exhibits contradictions in its very nature. There are, however, views other than the abstract, and in ordinary life the Skeptic's arguments don't have the force to counterbalance the natural conclusions of sense and experience. But some fields are very far from these natural conclusions of sense and experience, and one of those fields is natural religion, which deals with things like God and the eternity of the world.
Cleanthes is unconvinced. Skeptics, whatever they may say, don't merely adhere to conclusions in ordinary life; they do so in abstract philosophy as well. And this is all to the good: it would be absurd not to adhere to solid scientific conclusions, however abstract, even if one does not attribute to them a complete certainty. The examples Cleanthes gives are Newton's analysis of the rainbow and the arguments put forward by Galileo and Copernicus for the motion of the earth. These examples are not picked out at random; they are carefully selected by Hume, and they, too, will affect the course of the argument. But at the moment Cleanthes's point is simply that in actual practice, through most of philosophy and science, philosophical skeptics are necessarily skeptics about particular questions, each of which has to be taken on a case-by-case basis, and not about whole fields. So why, Cleanthes asks, does the philosophical skeptic suddenly change tactics in religious matters? There is no legitimate distinction to be made between one field of philosophy and another, or between philosophy and common life. The arguments are similar in each; and in each they carry the same force. No one is so silly as to reject physics simply because it's difficult and often far removed from sensory experience; so the fact that a field has these qualities is simply not an adequate reason for rejecting the ability of human reason to handle it. The arguments still must be considered point by point.
Part II continues to set up an argument; immediately we get another distinction that is essential for understanding the future course of the argument. Demea points out that it is one thing to be skeptical about our knowledge of the divine being, i.e., the existence of God, and another thing to be skeptical about our knowledge of the divine nature. Demea takes the former to be simply self-evident; the latter, however, is altogether unknown to us by our "finite, weak, and blind" reason. The greatest impiety is to deny that God exists; the second greatest is to pry into God's nature and affairs. Philo agrees that the two matters are distinct, and then says something very important:
But surely, where reasonable men treat these subjects, the question can never be concerning the Being, but only the Nature, of the Deity. The former truth, as you well observe, is unquestionable and self-evident. Nothing exists without a cause; and the original cause of this universe (whatever it be) we call God; and piously ascribe to him every species of perfection. Whoever scruples this fundamental truth, deserves every punishment which can be inflicted among philosophers, to wit, the greatest ridicule, contempt, and disapprobation. But as all perfection is entirely relative, we ought never to imagine that we comprehend the attributes of this divine Being, or to suppose that his perfections have any analogy or likeness to the perfections of a human creature.
This passage in particular needs to be read closely; and keeping it in mind as you go through the Dialogues will keep you from falling into the common misunderstandings of what Philo is doing. We will see again the points made here.
Cleanthes turns to Demea and tells him how he conceives the matter, and in the course of doing so he gives the argument that will be under discussion for the rest of the book:
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 senses and faculties can trace and 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 contrivance; of human designs, thought, wisdom, and intelligence. Since, therefore, the effects resemble each other, we are led to infer, by all the rules of analogy, that the causes also resemble; and that the Author of Nature is somewhat similar to the mind of man, though possessed of much larger faculties, proportioned to the grandeur of the work which he has executed. By this argument a posteriori, and by this argument alone, do we prove at once the existence of a Deity, and his similarity to human mind and intelligence.
Three things in particular need to be noted about this argument. First, it is an argument based on the rules of analogy. Second, it is 'a posteriori', i.e., from sense and experience. Third, Cleanthes commits himself to appealing only to this argument. All three of these points are essential to understanding the discussion that will ensue, and many people have been lead into serious misinterpretation of the argument by failing to remember one or more of these points.
Demea immediately rejects Cleanthes's approach, because he finds it shocking that anyone would claim that God's existence cannot be rigorously demonstrated; that it is not follows from the second and third of the points I just mentioned. Philo's immediate reaction, on the other hand, is to focus on the first of the three points, and immediately he goes on the attack against analogical arguments from experience. What strikes him about Cleanthes's argument is not that it appeals to experience (which is what strikes Demea) but that it makes use of the most uncertain possible appeal to experience, analogy. Surely, he says, the analogy between the universe and a house is not a very close analogy.
Cleanthes in reply to these insists that his argument makes the existence of God more than a guess or conjecture; that the analogy is fairly close, although imperfect; and that imperfect analogies can ground inferences that are much more than mere conjectures.
There is more to Part II, but I want to save the rest in order to talk about it together with Part III. This will suffice for now. To recap, I've identified the following key issues that are important for understanding the argument:
(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.
(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.
Most of the rest of the dialogue plays out masterfully like a well-ordered game. (1)-(5) are its rules. (6)-(8) are the initial positions of the characters at the opening of the game. Now the game is on, and Philo has the first move. More on that in the next post in the series.