Plantinga on Functions and the Theory of Evolution

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Plantinga on functions and the theory of evolution Michael Levin a a City College of New York,

Online Publication Date: 01 March 1997 To cite this Article: Levin, Michael (1997) 'Plantinga on functions and the theory of evolution ', Australasian Journal of Philosophy, 75:1, 83 - 98 To link to this article: DOI: 10.1080/00048409712347691 URL: http://dx.doi.org/10.1080/00048409712347691

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Australasian Journal of Philosophy Vol. 75, No. 1; March 1997

PLANTINGA ON FUNCTIONS AND THE THEORY OF EVOLUTION' Michael Levin Alvin Plantinga's recent analysis of warrant and, implicitly, knowledge [24, 25] focuses on what the mechanisms of cognition are for. A belief is warranted, on his account, iff produced by reliable cognitive processes whose function it is to produce true belief, working as they should in a cognitive environment for which they were designed [25, p. 194]. The distinctive reference to the function of cognitive processes is prompted by cases like that of the mountaineer who believes for no good reason that he can leap a wide crevasse, and succeeds because of his irrational confidence. His belief, though true, was intuitively unwarranted and, because a result of wishful thinking - whose function it is to produce morale, not truth - the analysis counts it as unwarranted; see [25, p. 16]. The 'appropriate environment' clause excludes Gettier cases; for instance, credulity - the mechanism producing belief in the testimony of others - is designed to function only when others are truthful. So, when Brown believes Smith's falsehood about Smith's owning a Ford, Brown's fortuitously correct inference that someone in his office owns a Ford does not count as warranted because it was formed in the wrong sort of environment; see [25, pp. 82ff]. My target here is not Plantinga's analysis itself, which, though facing problems,' seems promising. What does concern me is Plantinga's use of it against 'naturalism', the view that all living things, including ourselves, were created by the purposeless forces of Darwinian evolution. Plantinga holds that there can be no adequate naturalistic explication of 'proper functioning', 'appropriate environment' or their cognates, notions which, he concludes, make sense only by reference to a purposive deity ([25, p. 197]; he rejects an as-if approach to natural teleology as 'double-think' [25, pp. 214ff]). The naturalist is thus barred from calling any belief warranted or, indeed, ascribing natural functions to anything. To ascribe functions to cognitive mechanisms or other natural phenomena, we must embrace theism. ~ Actually, this is one of two epistemological thrusts aimed at 'metaphysical natural-

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C.D. Ankney, Louis and Paul Pojman, Jonathan Adler, Nickolas Pappas, John Greenwood, Paul Griffiths and Margarita Levin offered helpful comments. One migt~t ask why this account is not a version of reliabilism, although this may be a terminological issue; see [24, pp. 192, 199, 210; 25, p. 46]. One might also wonder whether 'appropriate environment' is not a rug under which to sweep Gettier puzzles. Plantinga evidently conceives• appropriate environments as those in which God intends our faculties to work, but using the presence of Gettier cases as a test for (in)appropriateness offers scant insight into the puzzle itself, Finally, the unreliability of wishful thinking alone, with no 'function' clause, seems sufficient to render the mountaineer's belief unwarranted. Plantinga might seek to strengthen his appeal to function with the fortuitous brain lesion (a recurring counter-example in [24, 25]), which has no function yet reliably produces true beliefs. However, intuition may find that beliefs produced by such flukes are warranted; the astronaut in Forbidden Planet, whose IQ is raised when he sticks his head in a Krell teaching machine, seems to figure out, hence know, much more. (See Plantinga's inconclusive discussion in [25, pp. 26-28].) 'So what's a poor naturalist to do?', Plantinga asks [25, p. 211]. Earlier [24, pp. 26, 135] he has 83

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ism'. Plantinga also maintains [25, ch. 12] that we have no reason to trust our faculties if they arose solely by Darwinian evolution - hence, since one of their deliverances is the theory of evolution itself, no reason to believe the theory of evolution. I discuss this argument later. I. Naturalism and 'Function' Plantinga rests his case against the naturalistic definability of 'function' on the failure of naturalistic analyses proposed by Pollock (discussed in [25, pp. 199-201]), Millikan [18], and Bigelow and Pargetter [3] (discussed in [25, pp. 200-211]). One might expect such a base to be too narrow to support Plantinga's sweeping conclusion, but he confidently announces [25, p. 196, fn. 6; p. 209, fn. 16, citing Nagel, Wright [29], Neander [21] and Griffiths [14]) that his arguments, particularly his 'Hitler cases', also put paid to all affiliated proposals. It is helpful to divide Plantinga's targets into causal-role (CR) and selected-effect (SE) analyses. We may begin with the former, which takes the function, F, of a trait or structure, S, to be the causal role S plays in some larger system (standard references are Cummins [8, 9]). Plantinga does not take up this view directly, instead attacking the idea that a thing's function is what it does ordinarily, to which he objects that artifacts and organismic traits may perform their functions only rarely, and malfunction most of the time. The latter point applies to CR as well, however, since a structure or behavioural drive incapable of F-ing cannot play the causal role of an F-er (see [8, pp. 458, 462]). Under CR, "'S cannot F but its function is to F" is self-contradictory. It will not do to say that an S-token, s, unable to F is nonetheless for F so long as most Ss can F, since, as noted, most Ss may be unable to F yet still be for F. This objection 3 seems to me decisive. The SE account (represented by Millikan [18, 19] and Bigelow and Pargetter [3] [with elements of CR]; also see Neander [21, 22] and Griffiths [14]) construes a function as an activity that persists because it is or was adaptive; a thing is for what got it selected in. Among the various effects of the first hearts was blood circulation, which enhanced the fitness of heart-bearers, yielding the present proliferation of hearts. Hearts are for pumping blood, but not going lub-dub, because blood-pumping but not the lub-dub sound enhances fitness. Plantinga objects that this account builds the theory of evolution into the meaning of 'function' [25, pp. 203, 208], adding that, as a result, SE must find Continued... chided certain critics of theism for being 'strident' and "a bit self-righteous'. Plantinga's own condescension toward non-theists is an equal impediment to objective discussion. Among others, (1) CR counts accumulation of water droplets in clouds as the function of dust motes during rainstorms. Cummins [8] and Amundson and Lauder [1] urge that such a usage is not wrong, merely 'strained and pointless" because (a) rainstorms are loosely structured, and (b) accumulation of droplets does not explain the rainstorm macro-process reductively, in terms of a different sort of micro-process. It seems to me, to the contrary, that 'dust motes are for accumulating moisture' is simply false. Dust motes fimction as accumulators, and, speaking generally, what CR explicates is 'S is functioning as an F-er' - which is weaker than 'S's function is to F'. (According to etiological analyses, the needed strengthening is that S's functioning as an F-er explains why S exists.) (2) CR takes as understood the notion of a functionally organized system, which needs defining as badly as "function'; see Plantinga [25, p. 209]. Seeking to make a virtue of these drawbacks, Prior [26] urges that ascriptions of functional organization are interest-relative. This appears to deny objectivity to functional ascriptions.

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'function' as applied to natural objects and artifacts ambiguous [p. 210]. CR advocates (e.g., Prior [26, p. 317]) echo these points, noting that functions were ascribed to traits of organisms long before anyone heard of Darwin. As stated these criticisms are too strong. 'Function' in 'The function of the heart is to pump blood' does mean just about what it means in 'The function of volleying in tennis is to overpower opponents', and a correct analysis should be as close to univocal as possible. However, as Griffiths [14] observes, an artifact's Creator selects it either from real alternatives by trial and error or from notional alternatives in thought, as certain of its effects are found satisfactory. By the same token, selection includes more than adaptation (i.e., natural selection). Nevertheless, Plantinga has a point; whether or not SE builds natural selection into its definition of 'function', it is plainly guided by the theory of evolution, whereas the ordinary usage of 'function' is not. Some SE advocates address the semantic issue by urging that their aim is to explicate the usage of scientists (thus Millikan [19]) or analyse the 'criteria employed by scientists (thus Neander [22]), not provide logically necessary and sufficient conditions matching ordinary usage. In the present context, Plantinga would be right to reject this defence. 'Function' is used in his definition o f 'warrant' in its ordinary, pretheoretical sense, whatever that may be (see [25, pp. 5if]); if 'function' is construable naturalistically only in some extraordinary sense (and theism rejected), 'warranted belief' becomes illformed. Assume that, as all of us employ the term in everyday life, 'warranted' beliefs are those produced by properly functioning cognitive equipment. To argue that a naturalist, too, can distinguish warranted from unwarranted beliefs because he can explicate 'proper function' as it occurs in some other context is an equivocation, evading rather than meeting Plantinga's challenge. Neander writes [22, p. 176]: 'it is unproblematic if Harvey's notion of a 'proper function', before the Darwinian Revolution, was different from the closely related notion used by biologists today, after the Darwinian Revolution. Scientific notions are not static. Harvey obviously did not have natural selection in mind when he proclaimed the function of the heart, but that does not show that modern biologists do not have it in mind'. Yes, but it does show that, even though a statement using 'function' made by modern biologists may be true, a homonymous statement made by Harvey or the man in the street may be false. 4 For all Neander has shown, 'Cognitive faculties have functions' is such a statement In any case, retaining the Darwinian requirement of competition leads to undue narrowness? Suppose all human societies have recognized private property. Among the many consequences of this institution, such as irking the Left, let us assume some only, for instance e n c o u r a g e m e n t of productivity, are necessary for society to continue. Anyone convinced of this would almost certainly call encouragement of productivity a function of property even though societies recognizing property rights have never competed against societies that do not 6 - even though, that is, there has been no selection for property. 7

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The fact is, scientific notions are static. Every concept is what it is. What the history of science reveals is the same label being attached over time to a succession of related concepts. See Jackson and Pettit [15, esp. pp. 117f]. The authors take themselves to be downgrading functional explanation in the social sciences per se, not merely one analysis of it. Property rights and other aspects of human morality may nonetheless extend evolved features of animal behaviour; see, e.g., de Waals [11]. CR theorists would insist that simply noting why societies need property, without reference to

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A topic-neutral definition of 'function' more abstract than 'selected effect' is evidently required. Of course, evolutionary adaptations can still satisfy a definition not explicitly mentioning adaptation or otherwise assuming Darwinism. Anything, including natural phenomena which in point of fact meet the conditions of a correct definition, will belong to its denotation. Naturalists may therefore seek a topic-neutral definition which nonetheless denotes evolutionary adaptations, and in some instances seek to explain functional intuitions via stories about selection. Now Plantinga would consider such skirmishing within the naturalist camp so much wasted effort because his 'Hitler cases' [25, pp. 203-204] administer the coup de grace to any version or extension of function-as-adaptive-consequence. In the central one, Nazi scientists induce a mutation in non-Aryans which both makes their visual fields uniformly green and causes them 'constant and severe pain' whenever they open their eyes. The Nazis then exterminate non-Aryans lacking this mutation, so that among non-Aryans the mutate displaces the gene for (what we cannot help but call) normal vision. But then the green visual field is adaptive, enhancing the reproductive fitness of its possessors by prompting Aryans to spare them. Non-Aryans come to possess the gene for the green visual field because the gene produces the field. Yet it seems absurd to say that the function of non-Aryan eyes is to cause painful blindness, that non-Aryan eyes are working properly when opening them hurts, or that doctors who help non-Aryans see (what we cannot help but call) normally are disrupting non-Aryan visual systems. II. Wright's Analysis Revisited Plantinga sometimes writes as if the Hitler cases just finish the rout of naturalism, but this is not so. Wright's 'explanatory effect' analysis [29, 30] survives the criticisms thus far levelled. According to Wright, an effect F of S is a function of S just in case S exists or persists because it Fs; i.e., a thing's functions are those of its effects that explain it. Hearts are for pumping blood since (we believe) there are hearts because they pump blood. In this case the "because', for the naturalist, proceeds as before via natural selection and genetic transmission, but the appeal to explanatory rather than selected effects is inherently more general. One advantage of this generality is that, while both the selected-effects and explanatory-effects analyses apply to types, the latter is more adaptable to tokens: where type S is for F, defining 'S-token s is for F' a s ' s is explained by the F-ing of a subclass S* of S' appears to cover standard caseU and dodge counter-examples. 9 Hearts exist because they 7

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its perpetuation, explains its function. However, such "viability explanations' (Wouters [28]) are enthymematic. Take the presence of haemocyanin in the blood of Helix, Wouters" working example of a viability explanandum, whose explanans is 'haemocyanin satisfies the need for a carrier of oxygen'. The explanans does not entail the explanandum unless Helix is in fact viable. A species wiped out by disease needed greater resistance, but that need cannot explain resistance that was never achieved! Missing (say etiologists) is something about haemocyanin sustaining itself via sustaining Helix, and so, too, for property. Sometimes s ~ S*. My umbrella exists because all umbrellas from its production line (were expected to) deflect rain. Possibly S*={s}. The first aeroplane was for flying because of its (expected) ability to fly. Suppose Martians so like the look of Earth umbrellas that they make copies for their museums. Martian umbrellas exist because of similar Terran umbrellas that fend off rain and which exist

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pump blood, and my heart exists (in part) because of the blood-pumping of the hearts of my ancestors. Etiological theories are said to have trouble providing tokens with functions, since no individual causes or selects for its own existence. But no individual has to; it need only be explained by the activity of some (working) subset o f i t s type. Sober [27] (also see Nozick [23]) rejects selectionist accounts of individual traits on the grounds that selectional processes explain how individuals lacking a trait are excluded from a population, but not how any individual in the population acquired the trait that admitted it - the job of the mechanisms of inheritance, whose explanatory role is sharply distinct. A net with a 1 inch mesh explains why all the fish in the catch are > 1 inch long, but not why any particular fish is. (There is also the meaning problem: Harvey had never heard of genotypes.) But Sober's point just underlines the need to replace 'select for' by 'explain [in some way]'. Natural selection saw to it that only humans with hearts made it to my parents' generation, and my parents' hearts sustained them long enough to transmit to me a genotype expressed as a heart; that explanation of my heart, selectional or not, warrants ascribing it a function. Actually, some tokens do (help) explain their own persistence; my heart persists because the blood it circulates allows me to get food to nourish my heart. (Again (see fn. 17) S* -- {s}.) As malfunctioning hearts cannot explain their own persistence, however, the definition of 'function' for tokens must be made more serpentine. Notice next that Wright's definition ~°does not require an S-token to F or be able to F in o r d e r to be for F. It allows my h e a r t to fail yet still be for p u m p i n g blood. Consequently, the definition accommodates malfunctions, '~ and indeed recognizes the possibility of most things malfunctioning or failing to perform their functions. If every heart suddenly sprang a leak and ceased to move blood - as might happen in an environment, such as a battlefield, unlike those in which hearts evolved - no heart would do what explains why hearts exist. If umbrellas came to be used as miniature tent poles without being damaged, and could still perform their function, they would fail to perform their function without malfunctioning. Wright thus clears the hurdle Plantinga erected against CR. Wright also clears Plantinga's other two hurdles. Since 'explain' is topicneutral, it does not presuppose Darwinism, although Darwinian adaptations satisfy it: if hearts exist now because the heart's pumping of blood helped the first possessors of this organ reproduce more readily and thereby make more hearts, the ability of hearts to

Continued... because they fend off rain - yet Martian copies are not for fending off rain. Why? Because Martian aesthetes would have copied Earth umbrellas no matter why they existed. No Martian umbrella exists because of the protective power of Earth umbrellas. Vestiges are handled similarly. The appendix was once for digesting cellulose, but there are no cellulose-digesting appendices that explain my appendix. My remote ancestors had appendices whose digestion of cellulose help explain appendix transmission, but insofar as one is willing to say these appendices explain my appendix, one will be willing to say my appendix is for digesting cellulose (only nobody eats cellulose anymore). A quicker way to vestigiality is to observe that my appendix cannot digest cellulose, so is not a token of the type of its cellulose-digesting predecessors. '° Used of the core idea of explanatory effect and its refinements, this phrase avoids disputes about attribution. " Prior [26] argues that the SE analysis cannot make sense of malfunction; Mitchell replies in [20]. Prior also urges that Wright's analysis cannot handle malfunctions because it takes's is for F' to imply that s actually Fs. But on Wright's definition as understood here, 's is for F' does not imply that s Fs or is capable of F.

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pump blood explains why there are hearts now. (And m y heart is explained by the bloodDownloaded By: [University Of Illinois At Chicago] At: 18:20 1 March 2008

p u m p i n g o f earlier hearts.) The ability o f the volley to intimidate opponents also explains w h y there is volleying in tennis. The inventor o f the volley, traditionally Bill Tilden, w a n t e d a tactic to intimidate o p p o n e n t s , and, seeing that the volley w o u l d have this effect, introduced it. Volleying exists because it (was and is expected to) intimidate. So 'function' receives the same m e a n i n g - explanatory effect - whether used o f adaptations or artifacts?-" (Including divine artifacts: if G o d made heat'~s to p u m p blood, blood circulation was an effect G o d w a n t e d and f o r e s a w hearts having. B l o o d circulation then explains hearts in just the way intimidation explains volleying.) The punctured hearts case suggests a naturalistic definition for 'environments appropriate for the f u n c t i o n i n g o f S', n a m e l y ' e n v i r o n m e n t s like t h o s e m e n t i o n e d in S'S functional explanation'. The environments appropriate for a Darwinian adaptation are those in which it evolved, t3 and the environments appropriate for an artifact are those in w h i c h it is intended to work. The appropriate environments for an artifact might s e e m to be those in which it does work, but ordinary usage dissents. If a gunsight designed to track lions in the veldt is effective only with lions in zoos, lions in their native habitat being too elusive, we would be more apt to say that the sight does not work than that i t works in an unanticipated way. '4 Since the sight exists to track lions in the veldt, the veldt is the e n v i r o n m e n t m e n t i o n e d in the sight's functional explanation, and that, w e see, is where c o m m o n sense thinks it should work. Plantinga also dismisses W r i g h t ' s analysis in particular because o f the counter-examples to it in the literature, particularly B o o r s e ' s [4, cited without c o m m e n t in 25, and 5]. These examples deserve attention, for they raise serious and interesting problems for any etiological analysis. In the most challenging case, a leaky pipe releases a gas which drives back a repairman seeking to close the leak? 5 The leak persists because it is releasing gas, yet release o f gas is not the leak's function. A second: 'Obesity in a man o f meager motivation can prevent him from exercising. Although failure to exercise is a result o f ~ There are intentionality problems, essentially those that split off real and notional selection; when a (possibly unrealized) intended effect explains the creation of an artifact, it is a belief about the effect, not the effect itself, which carries the explanatory bali. The definition of 'S is for F' must therefore ultimately he cast in terms of the essential occurrence of F-descriptions in the explanation of S. ~ A usage spreading among evolutionary theorists; see for instance Daly and Wilson [10]. ~4 Prior's [26] grape-peeler example suggests that she would say the sight is for use in zoos, which strikes me as a reductio of CR. Actually, the example is unclear, since she seems to be imagining that her aspiring grape-peeler has been used to behead prawns for some time ('with every prawn that goes through the machine [the claim] becomes a stronger one'). It then is natural to say that beheading has become its function - which Wright may accept because beheading explains the device's continued use. ,5 ]4, p. 72], simplified. Some of Boorse's countercases simply misfire. (1) "A hornet buzzing in a woodshed so frightens a farmer that he repeatedly shrinks from going in and killing it. Nothing in Wright's essay blocks the conclusion that the function of the b u z z i n g . . , is to frighten the farmer' [4, p. 75]. Nothing should block this conclusion. Entomologists consider buzzing a warning, and do say its function is protection. (2) A bullet lodged in Jones' brain accidentally keeps migraines from developing. Its preventing migraine is not why it remains embedded, but 'It is easy to imagine a doctor saying: "This bullet has been performing a useful function for you all these years, Mr. Jones'" [4, p. 81]. This is surely a play on words, the doctor's feeble effort at levity; in real life, I suspect, the doctor would say "service' instead of 'function'. He certainly would not say the bullet is for preventing migraine, whereas the heart is for pumping blood. Preventing migraine is the CR-function of the bullet, not its (literal) function.

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the obesity, and the obesity continues because o f this result, it is unlikely that prevention o f e x e r c i s e is its f u n c t i o n ' [4, pp. 75-76]. ~6 But an e x t e n s i o n o f W r i g h t ' s analysis excludes these countercases. The difference b e t w e e n hearts and B o o r s e ' s leak, to which intuition seems to be responding, lies in a difference between the role o f the efficient cause o f the leak - mounting gas pressure, say - and the role o f the efficient cause o f hearts, the process that builds hearts from protein. Not only does the heart exist because o f what it does, namely circulate blood, heart-building occurs because o f what it does, namely build hearts. The formation o f heart-muscle tissue is itself explained via the fitness advantage it confers on organisms by making (fitness-enhancing) hearts. In contrast, the pressure in the pipe did not mount because it was leading to a leak. The efficient cause o f the leak is not itself explained by what it does, nor is the efficient cause o f the lazy m a n ' s obesity, his appetite, explained by the obesity it causes. So B o o r s e ' s examples are blocked by defining F to be a function o f S iff S is explained by its leading to F and the efficient cause S' of S is explained by its leading to S. ~7W e may call this schema the 'chain condition'. Far from being ad hoc, the chain condition fruitfully organizes n e w intuitions. For instance, its iteration captures sequences o f functions. W e wish to say heart-building is

for building hearts, and we can say this because the e n z y m e s which make heart-muscle exist because they make heart-muscle. A n d that is also the function o f those enzymes, since their efficient cause, m - R N A , exists because it carries the D N A code for those e n z y m e s . . . In fact, participation in longish chains o f such explanatory loops seems part o f what is meant by ascribing functions to the structures and internal states o f organisms: hearts exist because o f what they do, the m e c h a n i s m s that make hearts exist because o f what they do, the m e c h a n i s m s that produce those m e c h a n i s m s exist because o f what they do. and so back. Indeed, an ' o r g a n i s m ' can be v i e w e d as a locus o f n u m e r o u s long chains. One might thus extend W r i g h t ' s analysis further, calling F a function o f S iff there is a chain o f efficient causes ending in <S, F>, every link in which is explained by its effect. ~ M o r e formally: iff there is a chain o f efficient causes <S 1 . . . . .

Sn_I=S, Sn=F>, n>3, such that S i is explained by Si+ 1 for i 3 of a chain is itself a chain, so the first and last links in a chain can explain and be explained by causes and effects outside it. But call a chain right-complete if its terminal member is not explained by any of its effects. An organism's survival terminates every right-complete chain within it; most of an organism's features have survival as their ultimate function, although survival itself has no function except perhaps more survival - a result of the extended chain condition congenial to intuition. Wright's analysis assigns a function to organisms, incidentally, namely gene replication. Chickens exist to (i.e., because they) make chicken genes. Now call a chain left-complete if its first member does not explain its cause. The extended chain condition implies that first members of left-complete chains have no function, and this too appears to be a deliverance of intuition. DNA is seemingly an initial cause; nothing exists because it makes DNA, except perhaps other DNA. At the same time, some of what DNA does, like produce m-RNA, explains why there is more DNA (m-RNA is for carrying DNA code, since m-RNA exists because it carries DNA code, which eventually means more m-RNA, and m-RNA explains the persistence of DNA). Yet it seems intuitively wrong to say DNA is for producing m-RNA, or tbr anything else; DNA just exists. From a sociological viewpoint - to take another example - people exist because they form social relations, which lead to institutions,

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nal analysis, and n=3 the chain condition. '9 Here arise a question and a new counter-example. The question: does the chain condition allow artifacts like volleying to have functions, i.e., does the efficient cause of volleying - the plan to overpower opponents by returning the ball on the fly - exist b e c a u s e it produces volleying? The counter-example extends Boorse's: suppose the pressure in the pipe increased because nobody in the room could reduce it before the pipe blew, and nobody wished to be nearby when the pipe blew. Here the efficient cause of the leak itself can be explained by the leak, yet the leak is still not for venting gas? ° Fortunately, the answer to the question also resolves the new puzzle case. Both theists and non-theistic naturalists may be expected to agree that beliefs, desires, fears and intentions are explained by the behaviours such states cause. A theist explains them as mechanisms God created for producing certain kinds of behaviour, while a Darwinian explains them by the adaptiveness of the behaviour they produce. For the naturalist, act-A-will-have-attractive-result-B expectations exist because they usually bring about actions (A) with fitness-enhancing effects (B); organisms tending to form fitnessenhancing plans transmit this tendency to offspring. On either view, actions explain action-causing psychological states in the way blood circulation explains hearts, and particular actions explain the particular psychological states that cause them in the way the circulation of my blood explains my heart. Tilden had the plan that caused volleying because of the production of other actions by other plans. I experience the apprehension that keeps me out of the alley at midnight because of the prevention of other reckless actions by other fears. Indeed, production of behaviour is the f u n c t i o n of psychological states, since the general conative and exploratory drives that produce fears and expectancies exist because they produce fears and expectancies - and the psychophysiological causes of those drives exist because they produce those d r i v e s . . . terminates a long chain? ~ ~

Continued...

which stabilize society. Yet no social phenomenon is explained because it produces people, so, from a sociological point of view, people are not for anything. They just exist. This point may have been missed because paradigm functions like blood circulation occur in the middle of chains. A referee objects that DNA may have been selected over other vehicles for transmitting form, in which case transmitting form is DNA's function. The point made here does not turn on this factual issue. If DNA was selected over other transmitters, the chemical process which forms DNA, not DNA, is the first member of the DNA chain. In that case the extended chain condition predicts that biological intuition will deny the DNA-forming processes a function (except perhaps self-perpetuation), and I think intuition so responds. '9 Think of the cause c i from S i to Si+ 1 as a map c i : S i ~ Si+ 1, and the explanation e i of S i by Si+ 1 as a map e i : Si+ 1 --~ S i. Composing these maps is natural: heart muscle tissue indirectly causes blood to circulate because the effect of heart muscle tissue, the heart, immediately causes blood to circulate, and the explanans of circulation, the heart, explains heart-muscle tissue. Where f(g) is the composite of f with g, we have duality: domain(ci+l(C i )) = range(e/(ei+l)) and range((ci+l(C i )) = domain(ei (ei+l)). This allows us to call F an indirect function ofS iffS indirectly causes F and F is the associated indirect explanation of S. The ultimate direct or indirect function of each link in a right-complete chain is its right terminus. 2o Suppose the pressure increase was caused by a chemical reaction allowed to proceed because, once started, nobody could move fast enough to prevent it from yielding the gas whose mounting pressure was expected to rupture the pipe. The chain now has four links, and could presumably be lengthened. So the example cannot be met, as I once thought, simply by requiring a large n in the chain condition. 2, People certainly think an artifact must be created by the intention to produce it. and in so

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It follows - turning to the counter-example - that the leak does not explain its efficient cause, the increase in pressure together with fear about the pressure causing a leak. Fear, and this particular fear, exist because of (other) fears that averted their objects. Consequently, only fears that help avert their objects can be explained by their behavioural effects, whereas the fear of the leak, by dint of circumstances, helps to create its object. So this fear, which is not producing the sort of effect that explains why there are fears, is not explained by the leak in the way in which a heart is explained by its pumping blood, or Tilden's stratagem by volleying. The leak does not explain its cause after all, leaving the chain condition violated) ~ III. The Hitler Case Again Wright's analysis having survived thus far, the Hitler case must succeed against it for Plantinga's anti-naturalism to be vindicated. In considering how the two fare, let us first note some ramifications of the Hitler case which, in his desire for vividness, Plantinga may have overlooked. For one thing, it is hard to understand how non-Aryans left to themselves could survive or reproduce. They would be unable to find their way around by themselves in a world full of hostile Nazis, and their constant discomfort would presumably dull their sex drive. There would be no non-Aryans after the first generation, existing because of their visual fields or for any other reason. Since, like mules and seedless grapes, non-Aryans could not reproduce on their own, the Nazis would have to nurse them to maturity in special creches, creating each new generation by supervised insemination. In short, non-Aryans would have to be grown by Nazis much as exotic plants and animals are grown by human breeders now. And intuition treats designer life-forms, especially with respect to traits purposely bred in, as artifacts. The functions of such traits are the effects their human creators intend them to have. This is just what Wright's analysis predicts, since the exaggerated coats of show dogs, for instance, exist because of the pleasure they are expected to give humans. By the same token, the functions of traits of non-Aryans, according to Wright's analysis and the lights of intuition, would be determined by the purposes for which the Nazis bred them. The function of the green visual field would be to gratify Nazis, by exhibiting their scientific prowess and tormenting non-Aryans. The visual field of non-Aryans is supposed to be uniformly green, and if a non-Aryan were born able painlessly to make the visual discriminations Aryans do, his visual system really would be malfunctioning. We Continued... describing the intention they sense a non-linear causal relation between intention and act. Intentions are so basic to experience they usually go unnoticed, but if asked why they exist most people would probably say 'because they lead to action'. So the chain condition may well explicate what people have, dimly, in mind. That token psychological states exist because of similar, adaptive psychological states meets Ehring's objection [13] that Wright cannot accommodate impossible goals. In some of Ehring's cases, e.g., an animal trying to escape a hopeless trap, the animal acts as it does because of similar but adaptive actions by its ancestors. The efforts of conscious agents trying for the physically or logically impossible are also explained by successful ancestral efforts. The mental state of a would-be inventor of perpetual motion is a malfunctioning trying. What is more, physically or logically impossible end-states - which Nature cannot select for - are always goals of conscious agents. Non-conscious mechanisms with unrealizable goals, like Ehring's rocket meant to go faster than light, derive their goals from human intent.

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flinch from saying this, I suspect, not because it is false, but because the scheme Plantinga describes is so grotesque that any positive language, including success words like 'working properly', seems misplaced in connection with it. To see that I am not exploiting inessential features of the Hitler case, consider an induced mutation which allows mutates to reproduce. Once again to display their skill and single out non-Aryans, the Nazis manipulate non-Aryan genes so that non-Aryans grow small green bumps on their chins. The bump is adaptive, inducing Nazis to spare its possessors. Wright's analysis again predicts that gratifying Nazis is the function of the bump, and surely intuition agrees. The bump would be f o r gratifying Nazis even among nonAryans breeding freely after the fall of the Reich (unless it persisted because of acquiring some new adaptive function2~), since the bumps in the wild would exist because of th~ bumps that existed because they pleased Nazis. After all, a Martian wanting to know about the green bumps would be told that they were once bred in by N a z i s . . . Does the bump example go my way because it involves no interference with systems having already established biological functions? Well, consider a final case. Again from cruelty and arrogance, but carefully sparing reproductive capacity, the Nazis cause a small bone to impact non-Aryan eardrums, leaving non-Aryans able to discriminate fewer sounds than otherwise. Once again, I think, one is inclined to say that the function of the bone and the induced reduction in auditory range is to bother non-Aryans and exhibit Nazi ingenuity, precisely because these (expected) effects explain the b o n e ' s presence. Wright's analysis remains concordant with intuition. Yes, but d o n ' t we also wish to say that the bone. whose function may be to gratify Nazis, is an abnormality in the non-Aryan otic system, and similarly for the non-Aryan visual system? There is no real problem here. A trait can have multiple functions, and, since more than one of its effects can be involved in explaining its existence, Wright's analysis permits this. In particular, a selectively bred trait may have divergent artifactual and biological functions (and will if breeders think the trait has an effect it does not; see Griffiths [14, p. 421124). So we can say, and Wright permits us to say, that the biological function of the non-Aryan otic system is hearing, while its artifactual function is gratifying Nazis. Individuating traits and their functions more finely, the non-Aryan otic system as a whole is for audition (and insofar is malfunctioning) while the bone is for impeding creating a (biological) abnormality in - the otic system. Similarly, the non-Aryan visu-

_,3 Plantinga [25, pp. 201,204] imagines a primitive tribe ritually breaking the leg of each newbom. Some newborns escape with legs intact, but a taboo arises against mating with anyone who does not limp. If the ritual dies out but genetic changes produce females who prefer males with broken legs, giving males born with fragile legs a reproductive advantage through sexual selection, then - intuitively, and by Wright's lights - broken legs have acquired the function of attracting mates. Wright's analysis thus heeds the distinction between effects which entrench a trait and effects that may explain its later presence. It is thought that the baldness of buzzards was selected for because it dissipates heat, but by allowing scavenging buzzards to penetrate carrion without fouling themselves, it now persists because it confers a hygienic advantage. A (mere) effect has become a function by what Stephen Jay Gould calls 'exaptation'. 24 If the bone on the tympanum does not interfere with hearing, it is artifactually for impairing audition, albeit unsuccessfully - but since it persists because it fools Nazis into thinking it impairs audition, its biological function is to fool Nazis. I suspect most people would rank the artifactual function primary, since (a) Nazi intentions created, as well as sustain, the bone, while its biological function only sustains it; (b) 'impairs audition' but not 'is believed to impair audition' occurs in both the artifactual and biological explanations (see fn. 22); and (c) as biological functions go, 'fooling Nazis' is a bit rechercht.

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al system was, until the Nazis stepped in, for seeing; at that point it began to be for gratifying Nazis, and its attendant green field for gratifying Nazis simpliciter. IV. An Error Theory of Sorts? But the point, Plantinga might urge, is that we do want to say the non-Aryan otic system

is for hearing a certain range of sounds, and we want to say this because it is just obvious (see [25, p. 214]). So we do, but no it isn't. Our readiness to say that the bone creates an abnormality in non-Aryan otic systems is explained by our belief that the function of the tympanum is to transmit certain vibrations. We believe this because we believe the transmission of these vibrations explains why there are tympani. Some people think this explanation proceeds via the will of God, others that it proceeds via mutation and selection. The one belief involves a hypothesis about G o d ' s mind, the other a hypothesis about natural events in the remote past. In neither case can the belief that the tympanum has a function, being inherently etiological, 25just be seen to be true. 26 To say this is not to endorse an error-theory, according to which there is widespread agreement on incorrect ascriptions of function because observable features of organisms are widely misinterpreted as products of design. Non-theistic naturalists can agree that ascriptions of functions to natural phenomena have often been mediated by false theistic beliefs while insisting that these ascriptions were correct anyway, since many natural phenomena exist because of their effects and that is what it is to have a function. (Nontheistic naturalists can even allow pre-Darwinians to have known that some things exist because of what they do, so long as this belief was not inferred from the lemma that these things exist because God made them.) But suppose that naturalists are not entitled to the 'anyway', precisely because, as Plantinga holds, 'function' is not definable naturalistically. Perhaps some reply to this article will contain a decisive refutation of all etiological analyses, making clear that no amount of talk about explanatory effects captures what is meant by 'function'. We would then face a dilemma. We could say that human traits do have functions because God made us in his image [25, p. 197], that we somehow know this [25, p. 48], and that this is why we persist in ascribing functions. Or, we could say that we were made by blind natural forces, that only artifacts have functions, and that biology should jettison 'function'. The consequences of the second course would be far less serious than Plantinga supposes. As he reminds us, functional language is deeply rooted in the biological and social 25 Bigelow and Pargetter [3] find it plain that the heart of a lion that just popped into existence would have a function. Plantinga is sure [25, p. 203] that Adam's heart would have had a function had God made him out of dust. Etiologists agree about Adam, since his heart would be explained by God's wanting a pump in his chest. They would explain away the intuition that spontaneous hearts have functions by our inability to forget how real hearts originate. Bigelow and Pargetter argue that whatever is true of one of two identical entities, such as a natural and a spontaneous lion, must be true of the other, but the two lions are not identical. They agree in all time-independent properties, but differ in properties referring to their origins. A lion whose heart was not inherited differs from an atomwise identical lion whose heart was. 26 Plantinga might reply that we do know elements of God's plans by something like observation; he alludes repeatedly to Calvin's sensus divinitatus, in virtue of which some beliefs about God are 'properly basic', and speaks of the Internal Testimony of the Holy Spirit [25, p. 48]. This reply will persuade only those who are already theists (and, apparently, Christians). In the present context it begs the question.

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sciences [25, pp. 5, 197], but it is not rooted so deeply that it cannot be extirpated. Were it extirpated, we could still talk of mutation, selection and the transmission of characteristics via DNA, and explain phenotypes as the filtrate of those processes. Our cognitive faculties could still be said to be adaptive. We could, indeed, retain Plantinga's definition of warrant by replacing 'cognitive faculties whose function it is to produce true belief' with 'cognitive faculties which exist because they produce(d) true belief', and 'working as they should in a cognitive environment for which they were designed' with 'working as they did in an environment like the ones in which they evolved'. Biology and epistemology would lose only a word. V. Does the Theory of Evolution Undercut Itself? But thus naturalizing Plantinga's account assumes that our cognitive faculties do produce true belief in environments like those in which they evolved because they did produce true beliefs when they were evolving. If our faculties have survived for some other reason, there would be no grounds for trusting them even when they were functioning' properly, and the beliefs they produced would be unwarranted. And it is just this latter supposition, Plantinga maintains, that is eminently reasonable: there is no good reason to think our faculties were selected for, if selected for at all, because they yield truth. As a consequence, he concludes, belief in evolution is unstable. The naturalist begins by believing in evolution, notices that, on evolutionary grounds, his beliefs are unwarranted, so concludes that his belief in evolution is unwarranted - but since his doubts about evolution are themselves based on the theory, which he now deems unwarranted, he must once again believe in e v o l u t i o n . . . (see [25, p. 235]). Planfinga does not call evolutionary theory necessarily self-defeating. It would coexist peacefully with the belief that believing in evolution is rational if, according to the theory itself, our faculties evolved to be reliable. For then evolutionary theory would entail the reliability of belief in evolution. The self-defeat argument turns on there being reasonable explanations for the survival of our faculties other than their reliability. 27 Like many oral-tradition arguments against 'evolutionary epistemology', Plantinga's confuses truth with the whole truth and the function of an adaptation with a necessary condition for its performing its function, as well as ignoring the self-corrective character of inquiry. The confusions loom in an argument Plantinga adapts from Patricia Churchland: since our brains were selected in for their capacity to m o v e us adaptively - toward food and away from predators - 'there is no particular reason to think [the beliefs they produce are] mostly true or verisimilitudinous' [5, p. 218]. True or not, beliefs will survive so long as they get us to do the fit thing. Now, while this is so in point of logic, it is difficult to see how in f a c t mostly false beliefs could steer a creature toward prey and mates and away from danger. Perhaps adaptive behaviour is the (ultimate) function of a cheetah's internal representation of the world, including his representation of a gazelle as in 27 So Plantinga's argument differs from the old chestnut that determinism and materialism cannot be believed because, if one accepts either, he must believe that all his beliefs, including his belief in determinism or materialism, have been caused by physical causes rather than 'reasons'. This argument overlooks the possibility that a belief may be caused by what makes it true, thereby also its 'reason'.

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front and to the right of him, but that representation will not get the cheetah fed unless the gazelle is in front and to the right. Of course, the cheetah does not represent the gazelle's distance in microns, or his own position relative to Arcturus. However, these failings show only that the cheetah's representational system is imprecise and incomplete, not that it is incorrect. If the gazelle is ahead and to his right, the cheetah's representation is literally correct. Correctness for models of the world must be understood functionally: if image A represents the gazelle and image B represents the cheetah's body, and by so moving as to superimpose A on B the cheetah overtakes the gazelle, the relation of A to B faithfully represents the cheetah's position. Churchland's argument may apply to the fixed action patterns of lower organisms, stereotyped sequences of muscle firings cued by specific stimuli that simply move organisms and do not bear semantic predicates. According to neo-Darwinism, however, genes lay down more. They can also program learning, and learning is adaptive only if the beliefs acquired are correct. Genes tell complex organisms to repeat behaviour found to have reinforcing consequences, presumably because behaviour with those consequences enhances fitness. But if an organism so instructed misremembers which behaviour has what consequence, it will act less adaptively than more astute competitors, and be selected out. Since our ancestors survived to produce us, the beliefs on which they based their behaviour must have been fairly accurate. Plantinga sees the need to explain in detail how systematic error could fail to degrade fitness in the wild, and he offers several possibilities [25, pp. 223-227]. Since he says it is 'reasonable to suppose' that the probability of their disjunction given the theory of evolution exceeds 0.5 [25, p. 228], I will take them as empirical hypotheses. The question is whether, singly or disjunctively, they are anywhere as likely as the hypothesis that our faculties were adaptive because they yield(ed) truth. If not, belief in evolution stabilizes. Proposal 1) Beliefs might not be causally connected to behaviour; if a creature's beliefs are not connected to its behaviour, they would not have to be accurate for it to survive. Reply: Occam's razor. It is unparsimonious to suppose there are beliefs as well as on-board neural guidance systems. 'It can't be a matter of definition', says Plantinga0 'that there are neural structures or processes displaying both propositional content and causal efficacy'. Quite so; nor need the evolutionist maintain it is. He maintains, rather, that there are neural structures that guide behaviour, that these neutral structures do have propositional content determined in part by how they guide behaviour (see e.g., Dretske [12], Levin [16], McGinu [17]) and, in light of this, that it is gratuitous to posit beliefs as

well. Proposal 2) Beliefs might be epiphenomenal effects of behaviour or the neural causes of behaviour. Again, beliefs would not have to be true for behaviour to be adaptive.

Reply: again, Occam's razor. It is gratuitous to posit beliefs in addition to the neural structures controlling behaviour, should these neural structures do what beliefs are supposed to do and have propositional content as well. Proposal 3) Beliefs might control behaviour, but not in virtue of their propositional content. If so, they could be adaptive but false. Reply: it is hard to see how a belief could control behaviour systematically except in virtue of its content. When a hominid modifies a hand tool until it matches a mental image the sight of the hand tool evokes, it is

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natural to ascribe to the image the propositional content 'the way a hand tool should look'. A gazelle-caused visual image that grows as the cheetah nears the gazelle, remains stationary when he is motionless relative to the gazelle, mad so on, certainly seems to control the cheetah's behaviour in virtue of being 'of a gazelle'. Explicating the 'so on' is a daunting task, but even in current philosophy of mind, where ascription of content is a much-controverted topic, controversy centres on the Kantian question of how content can cause behaviour, not whether it does. (Eliminativists reject the question, to be sure, but Plantinga would be the last to embrace eliminativism.) Proposal 4) Our beliefs might be false and behaviour-guiding in virtue of content, and therefore maladaptive, yet survive because the genes coding for our belief systems also code for fitness-enhancing traits. Reply: it is hard to imagine any trait enhancing fitness strongly enough to offset the disadvantage of acting on falsehoods. No matter how beautiful an animal's plumage, it is unlikely to reproduce if it doesn't display to conspecifics. Proposal 5) The desire system might offset errors in the belief system. In one Plantinga scenario, early hominid Paul thinks tigers are harmless and wants to approach them, but he survives because he confuses approach with flight. In another scenario, Paul thinks tigers are illusions, but makes it a habit to run whenever he sees one to control his weight. Reply: say what? Or rather, how - how any such false-belief/offsetting-desire combination could be consistently adaptive. Does Paul also think one approaches everything, including dinner, by retreating? Does he think you only run toward tigers by running away from them? If so, what (adaptive) inferential process could have produced such an idea? And if Paul thinks predators are harmless, does he think receptive mates are dangerous? Even if one could tell a coherent story in which Paul lasts twenty minutes, Paul would assuredly be less fit than competitor Peter who wants to keep his distance from tigers and thinks the best way to do so is to avoid them. Peter's genes would almost certainly displace Paul's, and Peter's descendants - us - would be likely to have adaptive desires and true beliefs. Proposal 6) Perhaps the mechanisms that produce belief about everyday affairs had to have been reliable, but not the mechanisms that produce theories about matters unconnected to survival, 'the sorts of intellectual pursuits favoured by people past their reproductive prime: such pursuits as philosophy, literary criticism, set theory, and evolutionary biology' [25, p. 227; also see p. 232]? 8 Many people find this general idea somewhat plausible, but note first that the theory of evolution is not as abstract as topics, like the origin of time, that do bring human thought to 'the utmost extent of its tether' (Locke's phrase). Second - remembering that the issue is the consistency of evolutionary theory with its own credibility - evolutionary theory itself suggests that flexible, wide-spectrum capacities are often the most adaptive. Rather than develop a necessarily accurate everyday-belief system plus a less disciplined theorizing system, nature may have economized by selecting in one all-purpose thinking ability, invaluable for mundane tasks and yielding reflection on large sets and DNA as a by-product. In that case abstract speculation would exercise the same faculty that conIn fact, almost all major advances in mathematics and science have been made by males under 35, in their reproductive prime, suggesting some connection between abstractive ability and fitness.

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trois everyday thinking, and be as trustworthy. And there does seem to be agreement among psychologists that one general factor, under significant genetic control, is employed over the full range of cognitive tasks? 9 No hypothesis like 6) can be supported by instances of irreparable cognitive error, for citing an erroneous belief and the reality it gets wrong inadvertently shows that the error can be caught after all. Evidence that our theorizing mechanisms are untrustworthy must be indirect, emphasizing the uncertainty into which reason falls when dealing with abstractions. This may be why Plantinga harps on set theory, reminding us repeatedly [25, pp. 19, 43, 106, 110, 174f] that the seemingly self-evident unrestricted comprehension axiom turned out to be false. And there is a lesson in this episode from the history of thought, but not the one Plantinga intends. Unrestricted comprehension associates every property Px with a set {x: Px}; Russell's paradox follows when Px is x~x. This axiom was first stated by Frege in 1879, and independently by Cantor soon after. But what happened next? In 1897 Burali-Forti proved what amounted to a restriction on it. Cantor himself expressed awareness of a related issue two years later. Russell and Zermelo discovered the paradox in 1901. By 1923 numerous resolutions had appeared: type theory, the Aussonderung schema, the axiom of regularity, the set/class distinction. Mankind did not blindly embrace naive comprehension for ages, unlearn it only with great pain, and remain confused ever after. The principle had received virtually no thought before the end of the 19th century, was seen to be false within two decades of its enunciation, and repairs had come on line within another decade. Nothing in this episode indicates weakness in the handling of abstractions. The variant claim that evolution makes theories only as accurate as survival demands, so that they may deviate from truth by an undetectably small amount, is also incapable of summoning positive instances, and faces much contrary evidence. This evidence, moreover, suggests that, even if the general claim is (undetectably) true, it does not apply to the theory of evolution. A case in point will serve. In 1859 Lagrange announced that the perihelion of Mercury was shifting at the rate of 0.4 seconds of arc per year, contrary to Newtonian predictions. Despite the hegemony of classical physics, which might have been expected to obscure this discrepancy, astronomers agreed at once that the discrepancy was real and devoted much effort to resolving it. Overcoming an even deeper bias toward the Euclidean conception of space, Einstein finally explained the discrepancy by deducing an annual perihelion advance for Mercury of 0.43 seconds from the assumption that mass curves spacetime. Mankind thus managed to detect a phenomenon too small to bear on survival in the wild, reject a well-entrenched theory on the strength of this discovery, and find a new theory differing from the old one by just the minute amount needed. The moral of such tales is that, even if our faculties mislead us about some matter remote from experience, we canfind this out and correct for it by comparing the predictions of our theories to observation. Lagrange's measurements, refined as they were, are orders of magnitude cruder than what current nanotechology has achieved. More specifically, the space, time and energy scales dealt with in the theory of evolution lie well within demonstrated human competence. We can be sure errors of those magnitudes are 29 On the general factor see Carroll [7]; on heritability, see Bouchard et al [6].

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detectable, because they have been detected. Evolution may have denied us the concepts necessary to understand certain truths, but there is no evidence that evolution has fated us to theoretical error, particularly about evolution itself. The b e l i e f - based on evolutionary grounds - that our cognitive functions evolved to be reliable is itself stable, so the naturalization of Plantinga's functional account of warrant may proceed. There is then no need to justify the ways of God to epistemologists, or vice-versa.

City College o f New York

Received January 1996 Revised May 1996 REFERENCES

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