Wednesday, August 26, 2009

Hume's Critique of the Analogical Design Argument: What does it in fact show?

If you look at David Hume's discussion of the design argument you see several things going on. One thing he focuses on: He believes an analogy is better the more it tends to infer 'like' causes from like effects. He also makes another point about just when it is "safe" to infer what we might label "unlike causes" from like effects. In some quantifiable sense, when there is "more" in the effect, one can infer "more" in the corresponding cause and to just that extent, and no more, the two compared causes would be 'unlike':

The terminology here is vague. Let's look at some examples.

Suppose I were to drop onto an alien planet, wander around and find a see-saw constructed of wood, and nothing else. Suppose it is not merely tree trunks leaning on others in some fortuitous fashion, but finished wood, with a rotating joint of some sort. What could I infer about its origins?

1. There were trees at some point on this planet.

2. There were some number of beings capable of constructing a simple machine, and acquiring the materials for doing so.

3. I could infer that these beings were somewhat like ourselves, but would have to be very cautious about inferring beyond the data.

In the known cases I would be relying upon (my experiences here on Earth) I know that people of relatively unsophisticated levels of knowledge can build such things. I know a single person can. I know several can cooperate in making such a thing.

This is all I can safely infer. The more scientific sophistication I attempt to read into these people, or the more definite a number of creators I infer, the shakier the inference becomes, the more open to doubt and question. The data just doesn't allow that level of specification.

If I drop onto that planet and find a pocket watch, I can "get away with more" in terms of the inferences that are safe to make. At a minimum I have to posit a higher level of scientific sophistication, it becomes more likely that several people have cooperated over some period of time in making the watch possible, by designing and constructing, although it is still possible one person designed and/or constructed.

If I dropped onto the planet and found an I-Phone or a PC, the "case" would be even stronger along these lines. It would be more 'likely' that there were multiple agents involved, over a long period of time, with a sophisticated knowledge of electronics, and information processing.

The possibility would be very remote that these things just happened by natural unthinking processes. At some point I would simply scoff at the notion.

Hume would have us carefully hew to such methodological standards when applying analogical reasoning to any inference of a designer for the biological world. You will see he (or one of his three characters) is skeptical as to the claim that the two "effects" are truly enough alike to allow us to make such inferences, and presents some arguments to that effect. But, ignoring that line of thought we see Hume does allow, for the sake of argument, that the biological and artificial/mechanical are enough alike to allow analogical or inference-to-best-explanation style reasoning, for the purposes of seeing what we truly can "safely" infer.

He would say that the sheer complexity of organisms, if accounted for on a strict 'like causes bring about like effects' line of reasoning, will force us, even more strongly than in the case of the computer, to infer some indefinite number of cooperating designers no one of which has all the requisite knowledge himself. He argues that we should be inferring a sort of polytheism. He does this by pointing out that our world is full of complex 'systems' artifacts that are brought about in this way. Ships, for instance are the final product of a long history of such cooperation, conscious design, and trial-and-error, fly-by-the-seat-of-your-pants experimentation. Computers, as in the alien planet example, are another and better one, more closely matching the biological.

Hume and Paley do concentrate on macro-sized denizens of the biological world, while Behe and the modern IDers would have us focus on the micro-sized denizens (DNA, and molecular machinery inside the cell, the basic unit of biology. These, interestingly, are a close match to the computer in that they essentially depend, for their functioning on the creation, transcription and translation of something like machine code. A lucid presentation of this line of argument is Stephen Meyers new book Signature in the Cell.)


How exactly are Hume's points related to ID arguments we see today?

Does his argument do much damage to agent based explanations of molecular biology, or does it show us the limits of the design inference, while still allowing that it is a justified example of IBE?

On a related note: There are several agent-based hypotheses, drawn from analogies with the world of human creation, that seem to "follow the facts" of the biological realm in this analogical way. Traditional monotheism is one, polytheism another, and the "ancient astronaut" theory yet another. There are an indefinite number of such competing stories.

Should we entertain these hypotheses seriously as alternatives to the monotheistic design theory?

Should we entertain any of these ID theories as serious alternatives to non-agent based or naturalistic explanations of the micro-biological, such as the various theories of chemical evolution?

If, as might be the case, some number of competing but mutually inconsistent design theories fit the facts in the way Hume seems to indicate here, do we have any rational basis upon which to choose between them?

As a whole, should we consider the pool of agent-based explanations for the complexities of organic life (both macro and microscopic) to be more or less plausible than the pool of non-agent-based explanations?

Which is the most plausible non-agent-based, naturalistic explanation for the origins of life? How does it compare, in terms of plausibility, with the one agent-based explanation that you consider to be the most plausible?