- Dear Group:
Below is the third of a series of extracts from my article "Intelligent Design theory: the way forward?", Stimulus, volume 9, issue 2, May 2001, pp.8-13.
I invite you to comment on whether or not I have been accurate and fair in this comment on Dembski's design inference filter.
The Design Inference
The recent books by Dembski13, have been reviewed by Alan Padgett14 (a professor of theology and philosophy of science at Azusa Pacific University), who notes that the members of the ID movement are not
content with a good argument from design against philosophical naturalism, but they wish to insert "design" into the paradigms and explanatory traditions of the natural sciences. Most advocates of design
accept biological evolution, as long as that is not the whole story, and Padgett notes that this is a great step forward in the religion-science debate among conservative protestants.
Padgett also remarks that, in contrast to Swinburne15, whose version of the argument is that the whole of the universe is designed, Dembski and friends focus on the design of particular items within the
universe. By concentrating on the scientific and philosophic challenges to Darwinism, the ID theorists largely ignore the argument from design to the existence of God.
In his technical monograph The Design Inference, Dembski seeks to eliminate chance (as an explanation) through small probability, by means of an "explanatory filter" whose purpose is to use probability
estimates to "eliminate chance entirely." Dembski thereby attempts to give a rigorous analysis of the common informal logical reasoning concerned with causal explanations of why something happens. The
filter involves a succession of decision modes: if the event has high probability it is deemed to be due to natural law, if it has intermediate probability then it is ascribed to chance, while if it has
low probability together with "specified complexity" (something that involves prescribed patterns) then it is ascribed to design.
Padgett comments that Dembski has made a real advance in probability and information theory with his attempt to give a rigorous definition of design in terms of "complex specified information" (in relation
to patterns in the data), but he criticizes the explanatory filter. Dembski reduces all kinds of regularity to natural laws, but some regularities are not based upon the laws of nature. After reducing
all highly probable events to natural laws, Dembski then reduces all natural laws (necessity) to algorithms and mathematical functions; but not all laws of nature are mathematical, nor can they all be
given numeric values. Padgett says that Dembski is on firmer ground when stating that the laws of nature, if we know them all, will make a particular event probable if that event is indeed caused by such
laws. But we do not know all the regularities of the natural world. At best we can only talk about what is highly probable given our current knowledge. The filter demands that, in order to eliminate
chance, we are aware of all the "chance hypotheses" for any given event, but this demand seems out of reach. Thus this filter does not in practice always eliminate chance as Dembski wants it to.
Moreover, Dembski insists that natural causes cannot generate complex specified information, but Padgett notes that in the future it may be possible for us to understand how complex specified information
can be generated by self-organizing physical systems.
Padgett admires the ID group for putting forward a bold, empirical hypothesis, namely that the origin of life comes from some intelligent designer, but he questions the claims of this movement to "insert"
design back into science. He notes that ID is already part of such (social) sciences as economics, archaeology and anthropology. However, when ID people say "science" they usually mean natural science,
so in fact they wish to add ID to the paradigms and explanatory schemes of the natural sciences. But natural science focuses upon the natural world, both for its object of study and its explanatory
scheme. Padgett says that natural sciences explain things on natural terms. The natural sciences leave the study of intelligent agency to the social sciences, such as psychology. The natural sciences
can identify an event which, given our current knowledge, they cannot now explain. Perhaps, then, the event was designed. That is as far as natural science can go, and perhaps that is all the ID
movement needs æ to get scientists to look and see if certain facts about the world, especially facts about the origins of living systems, exhibit signs of design rather that natural causation. Padgett
sees no reason in principle why astronomers or biologists should be unwilling to do so -- apart, of course, from a prior commitment to naturalism as a world view.
I agree with Padgett's concluding remarks. He does not believe that the ID folks will win the day. He accepts the notion that life will some day be explained through natural causes, while insisting that
God is the origin of all natural things, natural causes, and natural laws. In this way design and evolution are not opposites. Rather, evolution is based upon natural regularities, which are in turn
created by God. Evolution is based upon design.
Dembski's design inference argument has also been criticized on philosophic grounds. After presenting some technical arguments, (to which Dembski has responded with a posting at his home page,
www.baylor.edu/~William_Dembski) Fitelson et al.16 make some general comments. They say that Darwinian theory makes probabilistic, not deductive, predictions, and there is no reason to think that the only
alternative to Darwinian theory is intelligent design. Further, to test evolutionary theory against the hypothesis of ID, you must know what both hypotheses predict about observables. If defenders of the
design hypothesis want to make their theory to be scientific, they need to do the scientific work of formulating and testing the predictions that creationism makes, and they must face this responsibility.
13 .William A. Dembski, The Design Inference: Eliminating Chance Through Small Probabilities (Cambridge University Press, Cambridge, UK, 1998)
14. Alan G. Padgett, "Creation by design: Is the intelligent-design movement asking natural scientists to work outside their proper focus?" Christianity Today: Books & Culture: Science Pages July/Aug.
2000, online at www.christianitytoday.com.
15. Richard Swinburne, Is there a God? (Oxford University Press, 1996)
16. B Fitelson, C. Stephens and E. Sober, "How not to detect design æ Critical notice: William A. Dembski: The Design Inference", Philosophy of Science 66 (1999), 472-488