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Review Author(s): Jordan Howard Sobel Review by: Jordan Howard Sobel Source: Mind, New Series, Vol. 112, No. 447 (Jul., 2003), pp. 521-525Published by: on behalf of the Oxford University Press Mind AssociationStable URL: http://www.jstor.org/stable/3489201Accessed: 27-03-2015 02:16 UTC

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Book Reviews 521 Book Reviews 521

would well serare beginning graduate students adequately versed in contempo- rary epistemology and should be especially welcome for that. At the same time important interpretative issues are thoroughly explored. And all this is done in a friendly and readable style. A considerable achievement is before us and hopefully a further significant boost to the number of serious students of Reid.

Department of Philosophy ROGER GALLIE

University ofAberdeen Old Brewery Old Aberdeen AB24 3UB Scotland

The Design Inference: Eliminating Chance Through Small Proba- bilities) by William A. Dembski. Cambridge: Cambridge University Press, 1998. Pp. xvii + 243. Hlb t3s.oo, $54.95.

CLast night the stars above shifted instantaneously to spell ('Go Toronto!', and after a moment flashed back to their original places. Don't tell me it didn't happen. Please help me to understand.'

William Dembski would oblige: 'Necessity by laws of nature can be elimi- nated in this case. Read my book for the elimination of Chance. That leaves "Design", which is to say, "Neither Necessity nor Chance". As for your ques- tion, your guess may be as good as mine, even if different. "We [or anyway you] may have to live without a [believable] causal explanation" (p. 227). One can see that a more informative title for his book, though this could hurt sales, would be Elimanating Chance Through Small Probabilittes: Step One an a Posst- ble Inference to Design. Having 'swept the field clear' of every relevant necessity and chance hypothesis that could be responsible for an event E (p. 50), there may be no tenable explanation for it of which one can think. In that case the conclusion, well communicated, is not that 'E is due to design' (pace pp. 49 and 222-3, emphasis added), but that E 'conforms to a pattern [blueprint or design]' (p. 227, emphasis added), as it must do in order that chance hypotheses for it should be eliminable. 'The notion of design that emerges from the design inference must not be confused with intelligent agency' (p. 227). (CDaWkill'S

title alludes to William Paley's (1802)' iS the only mention of Paley. There is not even an allusion to an allusion to Hume's Dialogues.)

Cha??ce Elimination Arguments (pp. 145-6, 165, 184-5 and 198). Here come illustrations to expose some of their twists and turns. Each concerns consider- ing the string S:

1100001101011000110111111101000110001101100111011100011001000010111101110

10011111010010100101011110

Let E be the event of my typing that string here and now (Toronto, March 22,

2002, 1:58 pm). Please wonder whether E resulted from a chance-process,

would well serare beginning graduate students adequately versed in contempo- rary epistemology and should be especially welcome for that. At the same time important interpretative issues are thoroughly explored. And all this is done in a friendly and readable style. A considerable achievement is before us and hopefully a further significant boost to the number of serious students of Reid.

Department of Philosophy ROGER GALLIE

University ofAberdeen Old Brewery Old Aberdeen AB24 3UB Scotland

The Design Inference: Eliminating Chance Through Small Proba- bilities) by William A. Dembski. Cambridge: Cambridge University Press, 1998. Pp. xvii + 243. Hlb t3s.oo, $54.95.

CLast night the stars above shifted instantaneously to spell ('Go Toronto!', and after a moment flashed back to their original places. Don't tell me it didn't happen. Please help me to understand.'

William Dembski would oblige: 'Necessity by laws of nature can be elimi- nated in this case. Read my book for the elimination of Chance. That leaves "Design", which is to say, "Neither Necessity nor Chance". As for your ques- tion, your guess may be as good as mine, even if different. "We [or anyway you] may have to live without a [believable] causal explanation" (p. 227). One can see that a more informative title for his book, though this could hurt sales, would be Elimanating Chance Through Small Probabilittes: Step One an a Posst- ble Inference to Design. Having 'swept the field clear' of every relevant necessity and chance hypothesis that could be responsible for an event E (p. 50), there may be no tenable explanation for it of which one can think. In that case the conclusion, well communicated, is not that 'E is due to design' (pace pp. 49 and 222-3, emphasis added), but that E 'conforms to a pattern [blueprint or design]' (p. 227, emphasis added), as it must do in order that chance hypotheses for it should be eliminable. 'The notion of design that emerges from the design inference must not be confused with intelligent agency' (p. 227). (CDaWkill'S

title alludes to William Paley's (1802)' iS the only mention of Paley. There is not even an allusion to an allusion to Hume's Dialogues.)

Cha??ce Elimination Arguments (pp. 145-6, 165, 184-5 and 198). Here come illustrations to expose some of their twists and turns. Each concerns consider- ing the string S:

1100001101011000110111111101000110001101100111011100011001000010111101110

10011111010010100101011110

Let E be the event of my typing that string here and now (Toronto, March 22,

2002, 1:58 pm). Please wonder whether E resulted from a chance-process,

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522 Book Reviews

specifically the process of hypothesis H that says that I generated E by flipping a fair coin 1oo times which, let us agree, would have been a 'random chance process' and recording in the order of their appearances each head by '1' and each tail by 'o'. According to the theory of Dembski's book, you could be enti- tled to eliminate this hypothesis in one of the following ways. From the ways of these eliminations can be seen (i) something of the complexity and diffculty of chance eliminations conducted according to the book, and (ii) how easy it can be for someone who has gotten the hang of them to eliminate chance hypothe- ses.

Elimination by a possible prediction' You bring to mind the 'information' I that the string S occurs in a book published by Cambridge University Press in 1998. 'Information' for purposes of a Chance Elimination Argument need not be true (p. 147), though as it happens this information is true. Setting aside your knowledge of the order of o's and 1'S in the string of E (looking away and pretending to forget it), you assume (p. 146), you pretend (p. 143), that I con- tains information concerning this order, and come up with the idea that the publication of S in 1998 'predicted' the string in E at least in the Pickwickian sense that '[a] subject ... exhibited' (p. 160) it in advance without predictive intent. Holding that thought, you formulate a description D that 'delimits' the string in E (pp. 136-7). Formulating even a matching description is in this case easy, it is 'tractable'. It can be simply copying (pp. 159-60).

Summing up so far: Description D 'specifies' E, for D 'delimits' E, and D is for you 'tractable' given I. To this can be added that E is for H conditionally independent of I (p. 145): Prob(E/H & I) = Prob(E/H). Random-chance hypothesis H 'screens off) this I from E. (It does not, David Lewis might cau- tion, screen off every 'information' that might come to mind. You could bring to mind the 'information' that the string S resulted from the random-chance process of H.) To get on with the elimination of H for E, to get into a particu- larly difficult stage of its reasoning, let me tell you that according to your needs and interests, and especially how important it is to you to avoid a 'false nega- tive' here, you look into the conditional probability not of a D on H to deter- mine whether it is 'small enough', but of Ds on Hs, certain 'generalizations' of D and (I add without prejudice) H. In Dembski's terms you identify 'probabil- istic resources' that your needs and interests (pp. 175 ff., 185 and 19l) make 'rel- evant' in this case. These 'relevant' resources are terms of Ds and Hs which 'factor them in'. The less important a false negative in the case is for you, the greater relevant 'probabilistic resources' and 'saturations'. (Pp. 183-4.) Let your needs and interests make the avoidance of a false negative in this case of almost no importance, you could care less, but not much less: let this stipulation regarding your needs and interests make appropriate for Ds the presentation of the string in E anywhere and anytime in space-time, and for Hs the genera- tion of length-loo strings by processes that agree in their chances with those of coin flips. You find, let us assume, that the probability of a Ds conditional on Hs is still small enough by the standard of Chance Elimination Arguments,

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Book Reviews 523

which standard is less than 'the magic number 1/2' (pp. 1go-8). It follows by the Law of Small Probability, the principle of these arguments, that E did not occur according to chance hypothesis H (pp. 48-50), or better, that ' [you are] war- ranted inferring that E did not occur according to chance hypothesis H) (p. 185, cf. p. 222). '[S]uccessful predictions are always specifications. Tractability is immediate ... Conditional independence is immediate as well ...' (p. 160, emphasis added). And the relevant conditional probability is less than 1/2. So away with H for E.

From this illustration it can be gathered that Dembski's theory would entitle us to conclude, regarding any event e of describable complexity at least as great as E's (which is not very complex as events go) with the providence of which event e we are hardly concerned (as is the case for most events), that e did not take place by a chance-process. 'Predictions' of the complexity of E could have been written down in advance, and saturations of the specifications of these predictions should all be less probable than not on saturations of all relevant chance hypotheses. Similarly, of course, for predictions of much greater com- plexity than that. I have heard that no two snowflakes are exactly alike. If that is right, and a snowflake lands on my nose, since it does not matter to me whether or not it landed there by chance, I think that according to the book I am entitled to infer that it did not land there by any 'relevant chance[-process] ... that could [have been] responsible for [that event]' (p. 50).

Elimination by possibly delimitingpatterns that include one that is actually delimiting. You identify the 'information' I that for any 1oo-length string of o's and 1'S, if h is the number of 1'S in this string and t is the number of o's, then the absolute difference Ih-tl is an even number n such that o S n S 98. Pre- tending that 1* 'contains' information about E 'it is a simple matter ... to for- mulate various " [discrepancy] patterns"' (p. 164), to make 'a list of patterns . . . [t]he more patterns' in the list the better 'for eliminating chance' (pp. 150-1). You produce the list of discrepancy patterns,

D°: Ih-tl = o; D2: Ih-tl = 2; ...; D98: Ih-tl = 98.

Included is the pattern D8, gh-tl = 8, that 'delimits' E: in the string of E, h = 56, and t = 44. D8 specifies E, for E is for H conditionally independent of the infor- mation Is you used easily (which takes care of tractability) to formulate D8: since I is necessarily true, Prob(E/H & I+) = Prob(E/H). Avoiding a false neg- ative is, we suppose for this illustration, rather important to you. For definite- ness let its importance lead from D8 to the slight 'saturation', 'a 56/44 string of 1'S and o's in a philosophic text other than Dembski's and this review during the last decade', and, for H, the saturation Hs above restricted to generations of strings for philosophic texts. You find that Prob(D8s/Hs) < 1/2 . (Calculations for the reasonableness of this finding are in a note to the version of this review that is linked to my home page, http://www.scar.utoronto.ca/ sobel/.) It fol- lows by the Law of Small Probability that E did not occur according to chance hypothesis H, or better, that you are entitled to conclude that it did not.

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524 Book Reviews

From this second illustration it can be gathered that Dembski's theory ena- bles moderately imaginative persons easily to eliminate relevant chance hypo- theses for an event, if avoiding 'false negatives' for these chance hypotheses is somewhat (it need not be very) important for them. The theory allows imagi- native persons to work these eliminations with lists of possible delimitations of the event, lightly saturated.

From our illustrations, we may gather that by Dembski's lights not much happens by chance. His theory allows moderately clever persons (almost?) always to eliminate all relevant chance hypotheses. Presumably the theory implies that (almost?) always all relevant chance hypotheses are false.

You would be right if, by a Chance Elimination Argument, you eliminated H for E. I did not generate S by flipping a fair coin 1oo times and recording in the order of their appearances each head by '1' and each tail by 'o'. I copied it from page 32 of The Design Inference. Suppose, however, that reading that book some time ago, you wondered as you considered the string whether Dembski generated it by flipping a fair penny 1oo times, noting the string of heads and tails produced, and letting '1' stand for each head, 'o' for each tail. If it was not very important to you to avoid a 'false negative' regarding it, you were entitled to eliminate that chance hypothesis in essentially the first way, using the 'infor- mation' I (were you to bring it to mind) that exactly S was going to be 'post- dicted' (Pickwickian) in a review of the book, and you remained entitled to eliminate it after reading directly under it, 'This is in fact a sequence I have just now obtained by flipping a [fair] penny loo times' (p. 32). According to the theory of the book you would be entitled not to believe the book, and to con- clude that Dembski was either lying or mistaken when he wrote that! And there is worse. Dembski himself was entitled, when reading his published book, to eliminate that chance hypotheses concerning the string on page 32 in light of the 'information' of the string's 'prediction' (presumably false 'infor- mation'), unless it was then much more important for him, in which case he could be entitled to eliminate 'null saturations' of D and H identical with D and H, or saturations near enough to them for 'the magic number 1/2'.

'Surely, however, his Chance Elimination Argument does not entitle Dem- bski to eliminate that chance hypothesis, if he was for impeccable reasons sure that it was true, as he was barring reasons for him to doubt, when reading his book, his short-term memory, or his honesty, at the times of its composition.' The problem is that this argument of his can do that, for there is no place in it, there is no place in its principle, the Law of Small Probability, for 'prior' unconditional probabilities of challenged chance hypotheses.

Of the three types of probabilities that appear in Bayes's theorem posterior proba- bilities, likelihoods, and prior probabilities only one is relevant to the design infer- ence, namely, the likelihoods. The probability of an event given a chance hypothesis is the only type of probability we need to consider [when eliminating relevant chance hypotheses]. Posterior probabilities and prior probabilities play no role. This I take to be a huge advantage ... prior probabilities are often impossible to justify. (p. 68, emphasis added)

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Book Reviews 525

Omitting 'priors' from consideration is, however, not an advantage when 'filtering' explanations (pp. 36 ff.) for an event, if, as it surely does, this omis- sion seriously compromises the exercise no matter how it is detailed. ('Why are you looking for your keys here, under this lamp, when you know you dropped them there amongst the bushes?' 'Because there is more light here.' Not a good reason.)

It is a fatal flaw that, in contrast with Bayesian absolute, 'less-than-one-half', disconfirmation, Dembskian chance elimination proceeds without regard to 'prior' probabilities of the chance hypotheses that it would eliminate. Another serious deficiency is that, again in contrast with Bayesian absolute discon- firmation, this form of argument does not take into account merits of hypoth- eses 'against which . .. chance hypotheses [would] compete' (p. 68): again there are no 'places' in the Law of Small Probability for alternatives to a challenged hypothesis. Curiously, there is in the book implicit testimony to the effect that disregard by its main principle of hypotheses with which chance hypotheses 'under elimination' would compete is a deficiency of this theory: 'it is only by lacking/possessing warrant ['shades' of 'priors'] for attributing E to something other than chance that we can assert that E did/didn't occur by chance' (p. 220).

Suppose, as could happen, that a person has for good reasons eliminated every 'relevant' Necessity hypothesis of which he can think, and every 'rele- vant' Intelligent Design hypothesis of which he can think, for some event (for example, that stellar boost for Toronto). Suppose, as could be true, that for good reasons he despairs of finding a credible hypothesis of this event that involves either Intelligence or Necessity. It could be reasonable for this person to put the event down to Chance, pure chance, or reasonable for this person to maintain at least an open mind with regard to that possibility. Either way it would be unreasonable for him to 'sweep the field clear' of Chance.

There is, I think, enough going against the form of the Chance Elimination Argument to license omitting not only for lack of space, but also for what I consider lack of interest, discussion of, amongst other things, Dembski's appli- cation of it to an origin of life debate, arcane details and difficulties of the book's theory of 'specifications' of events for chance elimination arguments, its theory of 'probability resources' and 'saturations' of specifications, and the play in these arguments of 'the magic number 1/2'. For balance let me say that it is only for lack of space, and not lack of interest, that I omit discussion of Dembski's treatment of randomness (pp. 167-74), which William Wimsatt judges 'the most sophisticated to be found in the literature' (on the dust jacket of The Design Inference).

University of Toronto at Scarborough JORDAN HOWARD SOBEL

1265 Military Trail Scarborough, Ontario M1 C 1A4 Canada sobel@scar. utoronto. ca

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