How Not to Detect Design A review of William A Dembski s The Design Inference Eliminating Chance Through Small Probabilities Cambridge Cambridge University Press 1998 xvii 243 pg ISBN 0 521 62387 1 Branden Fitelson Christopher Stephens Elliott Sober Department of Philosophy University of Wisconsin Madison As every philosopher knows the design argument concludes that God exists from premisses that cite the adaptive complexity of organisms or the lawfulness and orderliness of the whole universe Since 1859 it has formed the intellectual heart of creationist opposition to the Darwinian hypothesis that organisms evolved their adaptive features by the mindless process of natural selection Although the design argument developed as a defense of theism the logic of the argument in fact encompasses a larger set of issues William Paley saw clearly that we sometimes have an excellent reason to postulate the existence of an intelligent designer If we find a watch on the heath we reasonably infer that it was produced by an intelligent watchmaker This design argument makes perfect sense Why is it any different to claim that the eye was produced by an intelligent designer Both critics and defenders of the design argument need to understand what the ground rules are for inferring that an intelligent designer is the unseen cause of an observed effect Dembski s book is an attempt to clarify these ground rules He proposes a procedure for detecting design and discusses how it applies to a number of mundane and nontheological examples which more or less resemble Paley s watch Although the book takes no stand on whether creationism is more or less plausible than evolutionary theory Dembski s epistemology can be evaluated without knowing how he thinks it bears on this highly charged topic In what follows we will show that Dembski s account of design inference is deeply flawed Sometimes he is too hard on hypotheses of intelligent design at other times he is too lenient Neither creationists nor evolutionists nor people who are trying to detect design in nontheological contexts should adopt Dembski s framework The Explanatory Filter Dembski s book provides a series of representations of how design inference works The exposition starts simple and grows increasingly complex However the basic pattern of analysis can be summarized as follows Dembski proposes an explanatory filter 37 which is a procedure for deciding how best to explain an observation E 1 There are three possible explanations of E Regularity Chance and Design They are mutually exclusive and collectively exhaustive The problem is to decide which of these explanations to accept 1 2 The Regularity hypothesis is more parsimonious than Chance and Chance is more parsimonious than Design To evaluate these alternatives begin with the most parsimonious possibility and move down the list until you reach an explanation you can accept 3 If E has a high probability you should accept Regularity otherwise reject Regularity and move down the list 4 If the Chance hypothesis assigns E a sufficiently low probability and E is specified then reject Chance and move down the list otherwise accept Chance 5 If you have rejected Regularity and Chance then you should accept Design as the explanation of E The entire book is an elaboration of the ideas that comprise the Explanatory Filter 1 Notice that the filter is eliminativist with the Design hypothesis occupying a special position We have interpreted the Filter as sometimes recommending that you should accept Regularity or Chance This is supported for example by Dembski s remark 38 that if E happens to be an HP a high probability event we stop and attribute E to a regularity However some of the circumlocutions that Dembski uses suggest that he doesn t think you should ever accept Regularity or Chance 2 The most you should do is not reject them Under this alternative interpretation Dembski is saying that if you fail to reject Regularity you can believe any of the three hypotheses or remain agnostic about all three And if you reject Regularity but fail to reject Chance you can believe either Chance or Design or remain agnostic about them both Only if you have rejected Regularity and Chance must you accept one of the three namely Design Construed in this way a person who believes that every event is the result of Design has nothing to fear from the Explanatory Filter no evidence can ever dislodge that opinion This may be Dembski s view but for the sake of charity we have described the Filter in terms of rejection and acceptance The Caputo Example Before discussing the filter in detail we want to describe Dembski s treatment of one of the main examples that he uses to motivate his analysis 9 19 162 166 This is the case of Nicholas Caputo who was a member of the Democratic party in New Jersey Caputo s job was to determine whether Democrats or Republicans would be listed first on the ballot The party listed first in an election has an edge and this was common knowledge in Caputo s day Caputo had this job for 41 years and he was supposed to do it fairly Yet in 40 out of 41 elections he listed the Democrats first Caputo claimed that each year he determined the order by drawing from an urn that gave Democrats and Republicans the same chance of winning In spite of his protestations Caputo was brought up on charges and the judges found against him They 2 rejected his claim that the outcome was due to chance and were persuaded that he had rigged the results The ordering of names on the ballots was due to Caputo s intelligent design In this story the hypotheses of Chance and Intelligent Design are prominent But what of the first alternative that of Regularity Dembski 11 says that this can be rejected because our background knowledge tells us that Caputo probably didn t innocently use a biased process For example we can rule out the possibility that Caputo with the most honest of intentions spun a roulette wheel in which 00 was labeled Republican and all the other numbers were labeled Democrat Apparently we know before we examine Caputo s 41 decisions that there are just two possibilities he did the equivalent of tossing a fair coin Chance or he intentionally gave the edge to his own party Design There is a straightforward reason for thinking that the observed outcomes favor Design over Chance If Caputo had allowed his political allegiance to guide his arrangement of ballots you d expect Democrats to be listed first on all or
View Full Document
Unlocking...