Intelligent design theory posits the existence of an intelligent creator as the best or only available explanation for the appearance of design we allegedly find in natural phenomenon like the cell. Intelligent design theory does not provide an argument for the existence of a God as conceived by any particular religion because it commits us to nothing specific about the nature of the creator except its capacity for intelligent design. And intelligent design is not grounded or justified on the basis of religious belief. The grounds offered for the existence of an intelligent designer are phenomenon we have discovered scientifically. Michael Behe (Design for Living, The New York Times, February 7, 2005) offers the following argument for intelligent design:
1. “We can often recognize the effects of design in nature.”
2. The appearance of design is present in biological phenomenon.
3. “We have no good explanation for the foundation of life that doesn’t involve intelligence.”
4. “In the absence of any convincing non-design explanation, we are justified in thinking that real intelligent design was involved in life.”
5. So, we are justified in thinking intelligent design was involved in life.
Behe claims the first two premises of this argument are uncontroversial. We can look at the Rocky Mountains and at Mt. Rushmore and see that one is the product of human design whereas the other is not. The appearance of design in this case is explained by what we know to be the case, that Mt Rushmore was in fact designed by humans.
Behe thinks we also find the appearance of design in biological phenomenon, notably in the structure and functioning of the cell. In the functional aspects of its parts and organization, the cell seems much like a factory, complete with machinery for locomotion, chemical processing and waste removal. But do the specific aspects in which we find genuine similarities justify seeing the parts of cells as machines? Complex molecules in the cell perform the function of transporting proteins from one place to another. Trucks perform a very similar function. But is this similarity sufficient for seeing the molecules that perform this function in the cell as intelligently designed transportation devices? Transporting things is a relatively generic function. Stars transport their satellites around galaxies, but this hardly warrants seeing stars as trucks or any other sort of transporting machine. Any number of further similarities between designed artifacts and cells and their parts may be identified. But supporting the second premise of Behe’s argument requires that we show that natural things like the cell are similar to artificial designed things like trucks and factories in at least some of the respects that are relevant to our judgment that the artificial thing is the product of design. This may or may not be possible. My only point here is to identify an appropriate standard for the justification of (2). If accepted, the second premise provides prima facia evidence for life being the product of intelligent design. But this prima facia case for design holds up only in the absence of other ways to account for the appearance of design. In the absence of alternative accounts, the existence of an intelligent designer is the best explanation of the appearance of design and this would give us abductive grounds for believing in an intelligent designer.
(3) claims that evolutionary theory has failed to yield a complete and adequate account of the origins of life. This may be true for reasons that have nothing to do with any defect in the theory of evolution by natural selection. It may be true, for instance, because we simply lack access to the historical evidence that would be needed give a complete developmental history of the cell. So scientists might have pretty good excuses for not being able to tell a detailed story about the development of cells in terms of natural selection. But mere lack of evidence is not an argument against thinking that natural selection played the sort of role in the advent of cells that we have good grounds for thinking it played in later evolution.
Even if (3) is true, it is deceptive in its suggestion that we do have a good explanation in terms of intelligent design. Here is the salient question: in just what way does the hypothesis that cells were designed by an intelligent designer explain? That humans designed trucks has explanatory power because it makes reference to a causal process that we have some acquaintance with. It is a process that involves engineers sitting at computers, building models, and so forth. But an appeal to a supernatural designer posits non-causal means about which we have no grasp what-so-ever. A supernatural creator is in some way acting outside the causal order and thereby producing effects in the causal order. Intelligent design theorists owe us some account of just how the design hypothesis is supposed to explain at all.
Finally, the main defect I find in Behe’s argument is a formal difficulty. If (2) is accepted and we grant the appearance of design in biological phenomenon, then we require some explanation of the appearance of design. But the issue shifts in Behe’s third premise. (3) claims that no adequate explanation has been given of the origin of life. The result of this shift of issue in (3) is that the argument presupposes without warrant that nothing short of an account of the origins of life through natural processes would suffice as an explanation of the appearance of design. But why should we expect that explaining the appearance of design requires giving a complete developmental history of the origins of cellular life? It could be, and I think in fact it is the case, that we have perfectly good explanatory principles at hand in the theory of evolution by natural selection but we simply lack adequate access to the historical evidence to explain how all of the impressive features of cells came to exist through natural selection.