Wednesday, February 7, 2007


The basic claim is that (some?) appearance of design in (some?) parts of nature is said to be evidence that there is an intelligent designer(s).

This kind of argument can be an argument from analogy, an inductive argument (i.e., a generalization from some cases), or an argument from the best explanation.

Paley and, especially, Cleanthes seem to offer an argument from analogy. We could present this most simply – too simply – like this:

  1. Watches and other complex machines have designers.
  2. Body parts are like, or analogous to, complex machines.
  3. So, body parts probably have designers too.

This argument is too simple because it doesn’t tell us how body parts are like or analogous to machines. So here’s a better attempt:

  1. Watches (and other complex machines) have (a) parts that (b) work together for a (c) purpose and (d) were designed to do so.
  2. Body parts[1] have (a) parts that (b) work together for a (c) purpose.
  3. Since watches and body parts are similar in ways (a), (b), & (c), they are probably similar in way (d) also.
  4. So, body parts are also probably designed.

You might rightly wonder why, according to Paley, you are supposed to accept claim 4 above that, “watches (and other complex machines) have (a) parts that (b) work together for a (c) purpose and (d) were designed to do so.” He seems to think this because he accepts this general claim:

  1. Anything[2] that (a) has parts that (b) work together for a (c) purpose is (d) designed.[3]

You might wonder what reason he has for accepting (8). Here are two possibilities:

    1. He uses the single watch (but also telescope) example to try to justify this completely general principle. If so, this is a rather poor induction. Also, while we might try to forget this, we already know that watches are designed: we don’t need to reason toward that conclusion.
    2. It’s an argument from the best explanation. What explains the fact that there are things, like the eye, ear, etc. with parts that work together for purposes?

(a) a random fluke, random matter just coming together in these ways?

(b) an intelligent designer(s)? or, a third, unconsidered possibility

(c) natural selection or evolution?

You judge something to be a better explanation relative to alternatives in mind. Perhaps (b) is better than (a) (is it, ultimately?). But perhaps (c) is better than (b). To try to decide, you need some general criteria for what makes an explanation better and worse. Philosophers of science try to understand what a better explanation is; it’s not easy to do so. But here are some proposals:

An explanation is better than another when it better (a) enables prediction, (b) enables understanding, (c) is simpler, (d) coheres with what we already know, (e) is able to explain a wide(r) variety of phenomena, (f) posits fewer entities or kinds of entities, (g) leads to future research, (h) can be tested, and can be supported and can be shown inferior (not that it will be, but that it can).

Given this set of ideals for an explanation (and some vague knowledge of biology and what most biologists think), what’s a better explanation: (b) or (c)? If (c), then perhaps Paley doesn’t have very good reasons for his (8) that anything that (a) has parts that (b) work together for a (c) purpose is (d) designed.

Another broad question about Paley’s strategy:

Suppose he “shows” that the eye, ear, and a good number of other body parts – since they have parts that appear to work together to serve a function – are designed. If so, he shows that there is a designer(s). Are we then suppose to think that the designer(s) of these body parts also designed the whole universe? If body parts were designed, then some parts of the universe were designed. But what about the other parts of the universe, or the universe as a whole (minus the eyes and ears found in it?)?

At the very least, it is not clear what the purpose or function of the entire universe is.[4] And we know so little about the universe: we have no clue what portion of it has parts that are working together, much less for any purposes.


If “Like effects prove like causes,” then – if machines and the universe are “like effects” (which the advocate of the analogy claims), then the causes of these like effects are similar. If you suggest an analogy you’ve got to go with it all the way for an argument to work based on it it. Uh oh!

What Machine designers are like:

So the designer(s) of the universe would be like:

  • Finite
  • Make errors, mistakes
  • Sometimes stupid, unoriginal, imitative
  • They try and try again to try to get it right; their models gradually improve
  • Multiple beings
  • Corporeal

Philo to Cleanthes, Part IV of the Dialogues Concerning Natural Religion

In a word, CLEANTHES, a man who follows your hypothesis is able perhaps to assert, or conjecture, that the universe, sometime, arose from something like design: but beyond that position he cannot ascertain one single circumstance; and is left afterwards to fix every point of his theology by the utmost license of fancy and hypothesis. This world, for aught he knows, is very faulty and imperfect, compared to a superior standard; and was only the first rude essay of some infant deity, who afterwards abandoned it, ashamed of his lame performance: it is the work only of some dependent, inferior deity; and is the object of derision to his superiors: it is the production of old age and dotage in some superannuated deity; and ever since his death, has run on at adventures, from the first impulse and active force which it received from him. You justly give signs of horror, DEMEA, at these strange suppositions; but these, and a thousand more of the same kind, are CLEANTHES’s suppositions, not mine. From the moment the attributes of the Deity are supposed finite, all these have place. And I cannot, for my part, think that so wild and unsettled a system of theology is, in any respect, preferable to none at all.

[1] All or just some of them?

[2] Should the domain of things here be restricted to, e.g., biological things?

[3] If this principle is true, if the concept of God seems to suggest a being with “parts” (sorta) working together for a purpose, then this principle would imply that God is designed, if God exists. But that can’t be right.

[4] If someone suggested that the purpose of the universe is to display God’s existence, this might be true, but if this is supposed to be a premise in an argument for God’s existence, then that argument would be question begging: C: God exists. Why think this? Because P1. The universe has parts working together for the purpose of displaying God’s existence. And P2: Since the universe has parts working together for the purpose of displaying God’s existence, God exists.

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