Naturalism's Argument from Invincible Ignorance:
By William A. Dembski
Howard Van Till's review of my book No Free Lunch is available at the AAAS Evolution Resources page -- http://www.aaas.org/spp/dser/evolution/perspectives/default.htm. The actual review is available as a pdf file at http://www.aaas.org/spp/dser/evolution/perspectives/vantillecoli.pdf. I respond to Van Till's review here.
Howard Van Till's review of my book No Free Lunch exemplifies perfectly why theistic evolution remains intelligent design's most implacable foe. Not only does theistic evolution sign off on the naturalism that pervades so much of contemporary science, but it justifies that naturalism theologically -- as though it were unworthy of God to create by any means other than an evolutionary process that carefully conceals God's tracks.
Following David Griffin, Van Till distinguishes four types of naturalism. The bottom line with all these types of naturalism is that science qua science must treat nature as a causal nexus that is impervious to any empirically discernible intelligent input from outside of nature. Naturalism, whether of the metaphysical or merely methodological varieties, treats nature as complete in terms of the causal principles inherent in it. Intelligent design, by contrast, questions that completeness, arguing that there can be good reasons for thinking that events happening in nature nonetheless lie beyond the capacities inherent in nature.
There is nothing strange or even counterintuitive about this claim so long as naturalism has not, as C. S. Lewis warned, worked its way into our bones. Howard Van Till, before he became steeped in process theology, would probably have accepted this possibility as well. Is it within the natural capacities of a corpse to come back to life after all physiological function has stopped for three days? The Judeo-Christian tradition is very clear that at least when it comes to salvation history, things happen that lie beyond the capacity of strictly natural forces. But naturalism in all its guises opposes such "supernaturalism."
Supernaturalism is a problem, but not for the reasons Van Till gives. The problem with terms like "supernatural" and "supernaturalism" (and I include here Van Till's variant of "extra-natural assembly") is that they tacitly presuppose that nature is the fundamental reality and that nature is far less problematic conceptually than anything outside or beyond nature. The "super" in "supernatural" thus has the effect of a negation.
But what if nature is itself a negation or reaction against something else? For the theist (though not for the panentheist of process theology), nature is not a self-subsisting entity but an entirely free act of God. Nature thus becomes a derivative aspect of ultimate reality -- an aspect of Godís creation, and not even the whole of Godís creation at that (theists typically ascribe to God the creation of an invisible world that is inhabited among other things by angels). Hence, for the theist attempting to understand nature, God as creator is fundamental, the creation is derivative, and nature as the physical part of creation is still further downstream.
Now, from the vantage of intelligent design, treated strictly as a scientific inquiry, neither naturalism nor theism has a privileged place. Intelligent design, as a scientific research program, attempts to determine whether certain features of the natural world exhibit signs of having been designed by an intelligence. Whether this intelligence is ET or a telic principle immanent in nature or a transcendent personal agent are all, at least initially, live options. The problem with ET, of course, is that it implies a regress -- where did ET come from? The same question doesn't apply, at least not in the same way, to telic principles or transcendent personal agents because the terms of the explanation are different. ET is an embodied intelligence, and that embodiment itself needs explanation. Telic principles and transcendent agents are unembodied. That raises its own issues, but they are a different set of issues.
The key question for intelligent design is whether we can rigorously determine that an intelligence is responsible for certain features of the natural world regardless what form that intelligence takes. This very question, however, raises the possibility that occurrences in nature divide into those that require intelligence and those that don't. It's such a division that Howard Van Till wants at all costs to avoid. Instead of intelligence and nature working in tandem, Van Till limits intelligence (increasingly a process God) to endowing nature with purely natural capacities that then are on their own to work themselves out in natural history. To keep this from degenerating into deism, Van Till invokes the vocabulary of process theology, which describes God as guiding or persuading creation. But all such talk is empty. Absolutely anything that happens in the world is compatible with such divine guidance (the process God always bows to the freedom of creation; by contrast, within classical theism, creation always bows to divine freedom).
Unlike Van Till's† process theology, intelligent design is not compatible with any sort of world. A world in which natural capacities can provide no empirical evidence of anything other than chance and necessity and additionally can do all of nature's design work is not a world in which intelligent design holds. But how can we tell whether natural capacities are able to account for everything that happens in nature? What evidence might count against natural capacities being able to account for all natural occurrences? And if intelligent design can show that natural capacities are in fact limited, does this not only open the door to supernatural interventions and miracles but indeed necessitate them?
Let's consider this last point, because it is one that Van Till thinks is particularly damning to my project and intelligent design generally. I argue in No Free Lunch that intelligent design does not require miracles or supernatural interventions in the classical sense of what I call "counterfactual substitution." Although the term counterfactual substitution is recent, the idea is ancient and was explicitly described in counterfactual terms by the theologian Schleiermacher. The idea is that natural processes are ready to make outcome X occur but outcome Y occurs instead. Thus, for instance, with the body of Jesus dead and buried in a tomb for three days, natural processes are ready to keep that corpse a corpse (= the outcome X). But instead, that body resurrects (= the outcome Y).
Now I claim that intelligent design, in detecting design in nature and in biological systems in particular, doesn't require counterfactual substitution. Van Till takes exception and writes: "How could the Intelligent Designer bring about a naturally impossible outcome by interacting with a bacterium in the course of time without either a suspension or overriding of natural laws? Natural laws were set to bring about the outcome, no flagellum. Instead, a flagellum appeared as the outcome of the Intelligent Designerís action. Is that not a miracle, even by Dembskiís own definition? How can this be anything other than a supernatural intervention?"
The fault in Van Till's argument centers on an equivocation over what it means to be a "naturally impossible outcome." To see what's at stake, imagine throwing a bunch of Scrabble pieces and seeing them spell Hamlet's soliloquy. Is this a naturally impossible outcome? It certainly is highly improbable, and such improbability often leads us to attribute impossibility (a pragmatic sort of impossibility). But would such a wildly improbable event require a miracle in the counterfactual-substitution sense of impossibility? Not at all. Scrabble pieces thrown at random are not, as Van Till might put it, "set to bring about the outcome, no Hamlet's soliloquy." Randomness, by definition, has free access to the entire reference class of possibilities that is being sampled. Any possibility from the reference class is therefore fair game for the random process -- in this case, the random throwing of Scrabble pieces. It's therefore not the case that this random process was set to bring about "no Hamlet's soliloquy."
Similar considerations apply to the bacterial flagellum. It's not that nature was conspiring to prevent the flagellum's emergence and that a designer was needed to overcome nature's inherent preference for some other outcome (as in the case of counterfactual substitution). Rather, the problem was that nature had too many options and without design couldn't sort through all those options. It's not the case that natural laws are set to bring about the outcome of no flagellum. The problem is that natural laws are too unspecific to determine any particular outcome. That's the rub. Natural laws are compatible with the formation of the flagellum but also compatible with the formation of a plethora of other molecular assemblages, most of which have no biological significance.
To return to the Scrabble analogy, there's nothing in the throwing of Scrabble pieces that prevents them from spelling Hamlet's soliloquy. This is not like releasing a massive object in a gravitational field which, in the absence of other forces, must move in a prescribed path. For the object to move in any other path would thus entail a counterfactual substitution and therefore a miracle. But with the Scrabble pieces there is no prescribed arrangement that they must assume. Nature allows them full freedom of arrangement. Yet it's precisely that freedom that makes nature unable to account for specified outcomes of small probability. Nature, in this case, rather than being intent on doing only one thing, is open to doing any number of things. Yet when one of those things is a highly improbable specified event (be it spelling Hamlet's soliloquy with Scrabble pieces or forming a bacterial flagellum), design becomes the required inference. Van Till has therefore missed the point: not counterfactual substitution (and therefore not miracles) but the incompleteness of natural processes is what the design inference uncovers.
I want next to consider Van Till's concern about the applicability of specified complexity to biology. Van Till writes: "In no case do we know with certainty all relevant natural ways in which some biotic system may have historically come to be actualized." He denotes "all relevant natural causes" that might be responsible for some biotic system X by capital "N" and distinguishes this "N" from lower case "n," which for him denotes "only those natural causes that are known to be relevant." His concern is that we can only calculate probabilities for X based on n rather than N. Yet to attribute specified complexity to X, Van Till contends, we would need to calculate the probability with respect to N and show that it is small enough. He concludes: "The more we learn about the self-organizational and transformational feats that can be accomplished by biotic systems, the less likely it will be that the conditions for complexity ... will be satisfied by any biotic system."
This last statement is wishful thinking. There's no reason to think that as our knowledge of n (i.e., known natural processes relevant to the formation of X) increases, that the probabilities or complexities associated with X become more manageable and that specified complexity thereby gets refuted or dwindles away. Within Van Till's notational convention, he is suggesting that as n approximates N, P(X|n) will continually increase. But that's not how probabilities work. With increasing knowledge, the probability may stay the same or even decrease. What's more, for an omniscient being who actually knows N, P(X|N) may be smaller than we ever imagined.
Van Till's mistake here should give us pause. He admits that increasing knowledge might refute an attribution of specified complexity to some biotic system X. But if that's a possibility, then certainly it's also a possibility that increasing knowledge might fail to refute an attribution of specified complexity and might even lead to increasingly extreme assessments of complexity. What's more, there's an underlying fact of the matter about what probabilities inhere in nature, and this fact of the matter might just be that the complexity/improbability of X is indeed as extreme as it now seems. Why then does Van Till think it's "less likely" that specified complexity will be borne out for biotic systems "the more we learn"? The likelihood to which Van Till is referring here has nothing to do with objective assignments of probability or complexity to biotic systems. Rather, this likelihood merely expresses Van Till's personal conviction that naturalistic explanations must inevitably triumph. Any such likelihood is thus purely subjective and flows from Van Till's precommitment to naturalism.
But what about Van Till's worry that increased knowledge might overturn an attribution of specified complexity? Clearly, increased knowledge need not have this effect -- increased knowledge of natural processes may merely drive the probabilities still lower and thus make the complexity even more extreme. Even so, Van Till finds particularly troubling the mere possibility that new insights into the natural processes surrounding some biotic system might overturn the attribution of specified complexity to it. But why should we take Van Till's worry seriously?
A little reflection makes clear that Van Till's worry cannot be justified on the basis of scientific practice. Indeed, to satisfy his worry is to impose requirements so stringent that they are absent from every other aspect of science. If standards of scientific justification are set too high, no interesting scientific work will ever get done. Science therefore balances its standards of justification with the requirement for self-correction in the light of further evidence. The possibility of self-correction means that science can, and indeed must, work with available evidence and on that basis (and that basis alone) formulate the best explanation of the phenomenon in question. That's why the "relevant" natural processes for the formation of some biotic system are those we already know and not those waiting to be discovered. Yes, we might be wrong in attributing specified complexity to some biotic system (welcome to science -- all of whose claims are subject to revision in light of further evidence). But we also might be right. And in the absence of detailed testable models for how material mechanisms could have formed irreducibly complex molecular machines like the bacterial flagellum, our best evidence suggests that it is indeed complex and specified and that we are right in attributing design.
To attribute specified complexity to a biotic system is to engage in an eliminative induction. Eliminative inductions depend on successfully falsifying competing hypotheses (contrast this with Popper's falsification method, where hypotheses are corroborated to the degree that they successfully withstand attempts to falsify them). Now, for many design skeptics, eliminative inductions are mere arguments from ignorance, that is, arguments for the truth of a proposition because it has not been shown to be false. In arguments from ignorance, the lack of evidence for a proposition is used to argue for its truth. A stereotypical argument from ignorance goes something like "gnomes exist because you haven't shown me that they don't exist."
But that's clearly not what eliminative inductions are doing. Eliminative inductions argue that competitors to the proposition in question are false. Provided that proposition together with its competitors form a mutually exclusive and exhaustive class, eliminating all the competitors entails that the proposition is true. This the ideal case, in which eliminative inductions in fact become deductions. The problem is that in practice we don't have a neat ordering of competitors that can then all be knocked down with a few straightforward and judicious blows (like bowling pins). Philosopher of science John Earman puts it this way (Bayes or Bust, p. 165): "The eliminative inductivist [seems to be] in a position analogous to that of Zeno's archer whose arrow can never reach the target, for faced with an infinite number of hypotheses, he can eliminate one, then two, then three, etc., but no matter how long he labors, he will never get down to just one. Indeed, it is as if the arrow never gets half way, or a quarter way, etc. to the target, since however long the eliminativist labors, he will always be faced with an infinite list [of remaining hypotheses to eliminate]."
Earman offers these remarks in a chapter titled "A Plea for Eliminative Induction." He himself thinks there is a legitimate and necessary place for eliminative induction in scientific practice. What, then, does he make of this criticism? Here is how he handles it (p. 165): "My response on behalf of the eliminativist has two parts. (1) Elimination need not proceed in such a plodding fashion, for the alternatives may be so ordered that an infinite number can be eliminated in one blow. (2) Even if we never get down to a single hypothesis, progress occurs if we succeed in eliminating finite or infinite chunks of the possibility space. This presupposes, of course, that we have some kind of measure, or at least topology, on the space of possibilities." To this Earman adds (p. 177) that eliminative inductions are typically local inductions, in which there is no pretense of considering all logically possible hypotheses. Rather, there is tacit agreement on the explanatory domain of the hypotheses as well as on what auxiliary hypotheses may be used in constructing explanations.
I want here to focus especially on Earman's idea that elimination can be progressive. Too often critics of intelligent design charge specified complexity with underwriting a purely negative form of argumentation. But that charge is not accurate. The argument for the specified complexity of the bacterial flagellum, for instance, makes a positive contribution to our understanding of the limitations that natural mechanisms face in trying to account for it. What justifies us in attributing specified complexity to the bacterial flagellum? The bacterial flagellum is irreducibly complex, meaning that all its components are indispensable for its function as a motility structure. What's more, it is minimally complex, meaning that any structure performing the bacterial flagellum's function as a bidirectional motor-driven propeller cannot make do without certain basic components.
Design theorists are therefore closing off possible avenues by which such systems might have evolved naturalistically. In particular, they've shown that no direct Darwinian pathway exists that incrementally adds these basic components and therewith evolves a bacterial flagellum. Rather, an indirect Darwinian pathway would be required, in which precursor systems performing different functions evolve by changing functions and components over time (Darwinists refer to this as coevolution and co-optation; Van Till gestures at such an indirect pathway when he invokes the type III secretory system as an evolutionary precursor to the flagellum -- more on this later). Plausible as this sounds to the committed naturalist, there is no evidence for the efficacy of indirect Darwinian pathways to accomplish irreducible and minimal complexity. What's more, evidence from engineering strongly suggests that tightly integrated systems like the bacterial flagellum are not formed by trial and error tinkering in which form and function coevolve. Rather, such systems are formed by a unifying conception that combines disparate components into a functional whole -- in other words, by design.
In assessing whether the bacterial flagellum exemplifies specified complexity, the design theorist is tacitly following Earman's guidelines for making an eliminative induction work. Thus, the design theorist orders the space of hypotheses that naturalistically account for the bacterial flagellum into those that look to direct Darwinian pathways and those that look to indirect Darwinian pathways (cf. Earman's requirement for an ordering or topology of the space of possible hypotheses). The design theorist also limits the induction to a local induction, focusing on relevant hypotheses rather than all logically possible hypotheses. The reference class of relevant hypotheses are those that flow out of Darwin's theory. Of these, direct Darwinian pathways can be precluded on account of the flagellum's irreducible and minimal complexity, which entails the minuscule probabilities required for specified complexity. As for indirect Darwinian pathways, the causal adequacy of intelligence to produce such complex systems (which is simply a fact of engineering) as well as the total absence of causally specific proposals for how they might work in practice eliminates them. In eliminating indirect Darwinian pathways, design theorists are therefore not merely eliminating what thus far hasn't worked (coevolution and co-optations) but also appealing to causal powers (designing intelligences) that are known to work.
Is this enough to justify asserting that the bacterial flagellum exhibits specified complexity? For the diehard naturalist (and I include here naturalistic theists like Howard Van Till), such an eliminative induction will never be enough and always constitute an argument from ignorance. But in refusing to countenance eliminative inductions that establish specified complexity, naturalists are guilty of their own argument from ignorance. Fearnside and Holther, in their classic Fallacy -- The Counterfeit of Argument, call it the argument from "invincible ignorance." Alternatively, they refer to it as "apriorism."
According to Van Till, design theorists have failed to take into account indirect Darwinian pathways by which the bacterial flagellum might have evolved through a series of intermediate systems that changed function and structure over time in ways that we do not yet understand (hence his appeal to the type III secretory system). But is it that we do not yet understand the indirect Darwinian evolution of the bacterial flagellum or that it never happened that way in the first place? At this point there is simply no evidence for such indirect Darwinian evolutionary pathways to account for biological systems that display irreducible and minimal complexity.
Is this, then, where the debate ends, with design critics like Van Till chiding design theorists for not working hard enough to discover those (unknown) indirect Darwinian pathways that lead to the emergence of irreducibly and minimally complex biological structures like the bacterial flagellum? Alternatively, does it end with design theorists chiding design critics for deluding themselves that such indirect Darwinian pathways exist when all the available evidence suggests that they do not. Although this may seem like an impasse, it really isn't. Science must form its conclusions on the basis of available evidence, not on the possibility or promise of future evidence. This means that eliminative inductions need to be local inductions, based on detailed testable models and hypotheses that are currently available.
If evolutionary biologists can discover or construct detailed, testable, indirect Darwinian pathways that account for the emergence of irreducibly and minimally complex biological systems like the bacterial flagellum, then more power to them -- intelligent design will quickly pass into oblivion. But until that happens, the eliminative induction that attributes specified complexity to the bacterial flagellum constitutes a legitimate scientific inference. The only way to deny its legitimacy is by appealing to some form of apriorism. The apriorism of choice these days is, of course, naturalism. And that apriorism engenders an argument not just of ignorance but of invincible ignorance. Indeed, any specified complexity (and therefore design) that might actually be present in biological systems becomes invisible as soon as one consents to this apriorism. If biological systems actually are designed, not only won't Van Till see it but he can't see it. This is invincible ignorance.
The remainder of Van Till's criticisms of No Free Lunch can be dispatched more quickly:
(1) Van Till is concerned that my use of chance encompasses all natural processes. But as he knows, I approach natural processes as a mathematician, and natural processes are modeled mathematically using stochastic processes. At any rate, Van Till's quibble is not with my definition but with the label to which I'm assigning the definition.
(2) Van Till claims that my probabilistic analysis of the bacterial flagellum is "radically out of touch with contemporary genetics and developmental biology." I'm not sure what developmental biology has to do with it (bacteria don't have embryos that develop into adults). As for genetics, he would have preferred to see the probabilistic analysis of the flagellum center on the genes that code for its proteins rather than the proteins that go into its assembly. But the genes follow the proteins which follow the function, and not vice versa, so my analysis is the correct one. Even so, since genes map to proteins, the probabilities assigned to the flagellum's proteins and assemblage can easily enough be backtracked to the genes themselves (this is standard probability theory, in which probabilities on the space mapped into backtrack to probabilities on the space mapped out of).
(3) Van Till is confused about how the detachability condition applies if the probabilistic analysis of the flagellum is confined to the genome. As he sees it, if the search for a detachable pattern is directed toward the base-pair sequence coding for the flagellum, then any such pattern could not be detached from the actual occurrence of that sequence. But this is false. The pattern is that collection of sequences which codes for a functioning bidirectional motor-driven propeller. This is no different from a cryptographic scheme in which† the plaintext (cf. protein assemblage) is detachable only if the ciphertext (cf. base-pair sequence) that maps onto it is likewise detachable.
(4)† Van Till seems to think that because the historical pathways by which biological systems evolved are almost invariably occluded, this gives credence to mechanistic theories of evolution. He writes: "Full causal specificity is, of course, the goal of all scientific explanations, but it is often very difficult to achieve, especially in the reconstruction of lifeís formational history. Thatís just a fact of life in evolutionary biology, as well as in many other areas of science." To see this absence of evidence as providing support for biological evolution itself constitutes an argument from ignorance. The only way to test whether material mechanisms are capable of driving biological evolution is by placing it in competition with something like intelligent design. Van Till's naturalism conveniently closes the door to any such competition.
(5)† Van Till has a problem with my characterization of the bacterial flagellum as a discrete combinatorial object. Nonetheless, that's what it is. Moreover, the probability I describe for such objects, which decomposes into a product of an origination, localization, and configuration probability, does in fact constitute the probability for such objects. That decomposition holds with perfect generality and does not presuppose any independence or equiprobability assumptions. Now, how one assigns those probabilities and sorts through the different possible estimates of them is another matter. Thus, for Van Till to remark that "no biologist has ever taken the bacterial flagellum to be a discrete combinatorial object that self-assembled in the manner described by Dembski" is besides the point. The bacterial flagellum is indeed a discrete combinatorial object, and the self-assembly that I describe is the one we are left with and can compute on the basis of what we know. The only reason biologists would refuse to countenance my description and probabilistic calculations of self-assembly is because they show that only an indirect Darwinian pathway could have produced the bacterial flagellum. But precisely because it is indirect, there is, at least for now, no causal specificity and no probability to be calculated. Design theorists are closing off possible mechanistic routes for biological evolution. Van Till's biologists, by contrast, handwave at mere conceptual possibilities.
(6)† In line with the previous concern, Van Till offers the type III secretory system as a possible precursor to the bacterial flagellum. This ignores that the current evidence points to the type III system as evolving from the flagellum and not vice versa (cf. Milt Saier's recent work at UCSD). But beyond that, finding a component of a functional system that performs some other function is hardly an argument for the original system evolving from that other system. One might just as well say that because the motor in a motorcycle can be used as a blender, therefore the motor evolved into the motorcycle. Perhaps, but not without intelligent design. Even if it could be shown that the type III system predated the flagellum (contrary to Milt Saier's work), it could at best represent one possible step in the indirect Darwinian evolution of the bacterial flagellum. But that still wouldn't constitute a solution to the evolution of the bacterial flagellum. What's needed is a complete evolutionary path and not merely a possible oasis along the way. To claim otherwise is like saying we can travel by foot from Los Angeles to Tokyo because we've discovered the Hawaiian Islands. Evolutionary biology needs to do better than that.
(7)† Van Till would have liked more detail showing that how bacterial flagellum is specified. Briefly: consider the reference class of possibilities to be all molecular assemblages (to keep things manageable let's limit them to a billion subunits). Now consider the pattern "bidirectional motor-driven propeller." This is a specification (I leave this as an exercise to the reader). Now do a perturbation tolerance and identity analysis as I describe it in section 5.10 of No Free Lunch. This restricts both the reference class and the specification to the actual flagellum for E. coli. Moreover, it allows us to estimate the probabilities for the naturalistic formation of the flagellum in line with John Leslie's fly-on-the-wall methodology.
(8)† Finally, Van Till attributes an argument to me that I never made. He writes: "If, as Dembski implicitly accepts, forming the majority of the E. coli genome -- including the portion dedicated to the actualization of the type III secretion apparatus -- did not need the form conferring intervention of a designer, then why would intervention be necessary for the small additional portion that codes for a flagellum?" I argue that the bacterial flagellum is designed because it exhibits specified complexity. But such an argument says nothing about the design or absence of it in the rest of the bacterium. Design and specified complexity must be established on a case-by-case, system-by-system basis. Moreover, the design of one thing need not preclude the design of another. I can, for instance, argue that the cassette player in my car is designed. But that leaves the design of the rest of my car untouched. Thus, when Van Till asks, "Does it not seem odd that the flagellar 2% needed supplementary designer-action while the other 98% did not?" he is certainly correct that it is odd. But the oddness here is of Van Till's own doing, attributing to me a position that I don't hold and for which I never argued.
I close with a quote by the late philosopher Willard Quine. Quine, though a naturalist, was not wedded to the methodological and metaphysical naturalism of Van Till. Quine was a pragmatic naturalist. This pragmatism allowed him to entertain the following possibility: "If I saw indirect explanatory benefit in positing sensibilia, possibilia, spirits, a Creator, I would joyfully accord them scientific status too, on a par with such avowedly scientific posits as quarks and black holes" (from "Naturalism; or, Living within One's Means," Dialectica 1995, vol. 49).
Quine's pragmatic naturalism is far more intellectually nimble than Van Till's naturalism, which, as we've seen, is scientifically stultifying and when pushed to extremes, as Van Till does, commits an argument from invincible ignorance. I would, therefore, that the scientific community take seriously the possibility raised by Quine of joyfully according intelligent design full scientific status. At issue is not the endless list of quibbles that Van Till raises, but whether intelligent design can confer explanatory benefit in understanding biological systems. That is now happening. To be sure, design theorists still have their work cut out. But it is an intellectual project that is fast gaining momentum and that promises shortly to displace Van Till's naturalism.
Van Till's naturalism is not an aid to intellectual clarity but a wet blanket designed to stifle inquiry. Not only is his naturalistically inspired critique consistently off the mark, but it makes a virtue of maintaining the status quo. The problem with web blankets and the status quo is, or course, that they are boring. Intelligent design, by contrast, as Karl Giberson and Donald Yerxa point out in their forthcoming Species of Origin (Rowman & Littlefield, 2002), is setting the agenda for the origins question in biology (and specifically for the emergence of biological complexity). Scientists therefore have a choice to make: to consider the possibility of intelligent design as a live option (if only for pragmatic reasons like Quine's) or to retreat into a naturalistic apriorism that eternally blinds itself to the very possibility of design. The choice here is between unfettered inquiry (with all the risks that entails) and invincible ignorance (with all the security and boredom it confers). It's clear which option Van Till has chosen.