Studies in History and Philosophy of Biological and Biomedical Sciences 42 (2011) 30–39

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Studies in History and Philosophy of Biological andBiomedical Sciences

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Darwinism after Mendelism: the case of Sewall Wright’s intellectual synthesis inhis shifting balance theory of evolution (1931)

Jonathan HodgeUniversity of Leeds, UK

a r t i c l e i n f o a b s t r a c t

Keywords:Darwinism

MendelismWrightFisherSpencerBreedingEntropyEquilibriaPanpsychismSynthesis

1369-8486/$ - see front matter � 2010 Elsevier Ltd. Adoi:10.1016/j.shpsc.2010.11.008

E-mail address: m.j.s.hodge@leeds.ac.uk1 For some exemplary disagreements, see Cain (2000

Historians of science have long been agreeing: what many textbooks of evolutionary biology say, aboutthe histories of Darwinism and the New Synthesis, is just too simple to do justice to the complexitiesrevealed to critical scholarship and historiography. There is no current consensus, however, on whatgrand narratives should replace those textbook histories. The present paper does not offer to contributedirectly to any grand, consensual, narrational goals; but it does seek to do so indirectly by showing how,in just one individual case, details of intellectual biography connect with big picture issues. To this end, Iexamine here how very diverse scientific and metaphysical commitments were integrated in SewallWright’s own personal synthesis of biology and philosophy. Taking as the decisive text the short final sec-tion of Wright’s long 1931 paper on ‘Evolution in Mendelian populations,’ I examine how his shifting bal-ance theory (SBT) related to his optimum breeding strategy research, his physiological genetics, hisgeneral theory of homogenising and heterogenesing causation and his panpsychist view of mind andmatter; and I discuss how understanding these relations can clarify Wright’s place in the longue duréeof evolutionary thought.

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1. Introduction

Familiarly enough, textbooks of evolutionary biology often tell asimple tale about what happened to Darwinism—meaning hereDarwin’s theory of evolution by natural selection—in the half-cen-tury after Darwin’s death in 1882. It was eclipsed, rejected in fa-vour of evolution by other means: the inheritance of acquiredcharacters (‘Lamarckism’) or saltationary megamutations and soon. The textbooks often tell a no less simple tale about what hap-pened next: Darwinism shines forth again, thanks to its novel,mathematical integration with the new Mendelian genetics. Asfor heroes in this vindicating, integrating synthesis, the triumvirateof theoretical population geneticists—R. A. Fisher, J. B. S. Haldaneand Sewall Wright (two Brits and a Yank)—are standardly citedas the great initiators, with their canonical texts all published justbefore that half-century ends in 1932.

Needless to say, historians of science have long been showingthat no such simple tales of triumphant mathematical-Darwin-

ll rights reserved.

) and Smocovitis (2000). For a rece

ian-Mendelian synthesis stand up to critical, scholarly scrutiny.Needless to say also, there is no easily epitomised consensus asto what to put in place of those simple tales. Perhaps there neverwill be.1 So, meanwhile, a single paper devoted to a single figurecan contribute most usefully by suggesting how complicated thestory of that individual can become, if we allow ourselves to getmore comprehensive as well as more detailed; if, that is, we allowourselves to ask how that individual’s diverse intellectual commit-ments may have come together in a personal synthesis. The presentpaper offers, then, an account of synthesis, but offers it as an antidotenot as a complement to the standard textbook synthesis stories.

A natural starting point in this exercise in historiographicalcomplication is to get a little more subtle and sophisticated aboutthe dreaded word, Darwinism; especially as it has already made anuncritical appearance in my opening sentence. What Darwinismhas been has obviously depended on who and what you were,and where and when: the German labour movement or the Vaticanin the 1870s, Harvard’s Museum of Comparative Zoology or the

nt fresh view of the synthesis period, see Cain (2009).

J. Hodge / Studies in History and Philosophy of Biological and Biomedical Sciences 42 (2011) 30–39 31

Institut Pasteur in the 1970s. As with institutions so with individ-uals: the book What is Darwinism? (1874) by Charles Hodge (not aknown relation), recently retired head of the Princeton TheologicalSeminary, famously answered that Darwinism was atheism. ForSewall Wright, in his formative years, just before the First WorldWar, as a graduate student—at Harvard’s Bussey Institution forresearch into biology in relation to agriculture and horticulture—Darwinism may well have been what was defended in Alfred Wal-lace’s book of that title published in 1889, based on his lectures inBoston and elsewhere in the US; or, most likely, what had beendiscussed more recently, in Vernon Kellog’s Darwinism Today,published in 1907.2

For both those authors, Darwinism was arboriform, adaptation-ist, gradualist selectionism: roughly the view that evolution hasmainly proceeded as reiterated, branching, gradual, adaptive diver-gences resulting from the accumulation of small, random individ-ual differences by the intraspecific selection arising fromcompetition among individuals in the struggle for existence en-tailed by excess fertility. As for Mendelism, that label has obviouslyto be used here not to signify Mendel’s own views; for it is in anycase now well understood that Mendel was no Mendelian in thesense that word had in the first years of the twentieth century.Rather, what is meant by Mendelism here are the new Mendeliandoctrines, especially about genes, their chromosomal linkages,combinations, recombinations and mutations, developed in thatcentury’s second decade, partly by Wright’s teachers, Castle andEast at Harvard, and, even more, by Morgan, Muller and others atColumbia.

Next, before going to Wright’s explicit comparisons and con-trasts of his views with Darwinism, in the sense of Wallace andKellog, we need to see where, when and what Wright was publish-ing in his earliest public expositions of his evolutionary theorising.It was well after finishing graduate school, and following severalyears at the United States Department of Agriculture (USDA) inthe capital, Washington, that Wright first wrote out his own viewson evolution in 1925. He did so in a typescript that was never pub-lished and is still not located today.3 In the years 1929–1932 hepublished those views in five publications: a very short abstract, afairly short paper for a statistics journal, a fairly long review of R.A. Fisher’s book The Genetical Theory of Natural Selection (1930), avery long article in 1931 (mostly, probably a revised version of the1925 typescript) in the journal Genetics—‘Evolution in Mendelianpopulations’—and a much shorter one in 1932, in the Proceedingsvolume for the Sixth International Congress of Genetics at Ithaca,New York , where Wright had presented it in person: ‘The roles ofMutation, Inbreeding, Crossbreeding and Selection in Evolution.’4

These last two would turn out to be the best-known papers of his en-tire career; and the second one has been the most influential becauseits diagrams of adaptive landscapes, not in any of the other fourtexts, have appeared so routinely in textbooks especially since theSecond World War.

The five publications all raise what Wright saw as the centralquestion he was offering to answer, and they all give the same an-swer to that question. It may be called Wright’s central evolutionquestion. In his formulations it asks: Given that evolution is cumu-lative change in the heredities of species, under what statistical orpopulational conditions is this cumulative change most rapid, con-tinual and irreversible, with or without environmental variation orchange? Wright’s answer is: When a large population is broken up

2 Hodge (1874), Kellog (1907) and Wallace (1889).3 Provine (1986), pp. 233–234.4 Wright (1929, 1930, 1931a, 1931b, 1932). All the papers by Wright cited in my paper he

the page numbers in that volume. In the list of references the original page numbers are5 Wright (1931b), p. 99.

into small local subpopulations with only a little interbreedingamong those subpopulations, and when there is inbreeding, ran-dom drift and selection within those subpopulations, and whenone or more subpopulations having individuals with selectively fa-voured, superior gene combinations exports those individuals toother subpopulations and so contributes to transforming the wholepopulation, the entire species. Later in his career Wright will callthis answer to this question his shifting balance theory of evolution(SBT); and this optimal statistical, populational scenario may becalled the shifting balance scenario (SBS).

In these five early SBT publications, Wright never locates hisviews in relation to anything as abstract or comprehensive as theword Darwinism often denoted. Indeed that word is not one hetends to use in print at this stage in his career. He does, however,position himself several times in relation to what he takes to bethe distinctive views of Darwin himself about the cases ofevolution.

In 1931, in his very long paper, in the journal Genetics, on evo-lution in Mendelian populations, his first full exposition of hisviews on evolutionary genetics, Wright twice positioned his viewsin relation to those of DARWIN (proper names got capitals in manyjournals then), rather than to any abstraction, Darwinism, such asWallace’s and Kellog’s titles invoked. Even in the two passages inthis one paper the issues raised by the two positionings differ.The first comes in the very opening pages where Wright is relatinghis paper to the present state of evolutionary theory. The relevanceto evolutionary theory of the twentieth century’s new geneticalscience is commonly acknowledged, Wright says; but only rarelyis sustained integration of genetical and evolutionary theory evenattempted. He distinguishes two ways to do this integration: thedirect or physiological and the indirect or statistical. The Lamarck-ian assumption that there is inheritance of acquired characters al-lows for physiological integrations; but, he says, those assumptionsare now discredited and so the integration must be statistical.Wright’s point here is that, on Lamarkian assumptions, the envi-ronment influences evolutionary change in species by affectingindividual developmental processes in ways studied by physiolo-gists, whereas, in accord with the recent rejection of thoseassumptions, the environment influences act on the species bydetermining what differences there are, within the population, inindividual chances of survival and reproduction. Darwin pioneeredstatistical or populational integrations, and his statistical factorswere differential survival and differential fecundity, Wright says.So, he here represents himself as having to be statistical and pop-ulational, as Darwin was, but for a reason that has arisen long sinceDarwin: the loss of the Lamarckian option. That is why evolution-ary theory must now be advanced by analysis of the statistical con-sequences of Mendelian heredity, which is what his paper is allabout.5

The second positioning comes toward the end of the paper.Wright has set out his view of the causes of evolution and has beenbriefly defending it as consistent with the relevant factual data,paleontological data especially. Comparing his view with Darwin’s,he insists that it is the same, except that he, Wright, in explainingadaptive divergence, does not appeal so exclusively as Darwin doesto intraspecific competition among individuals. For, he allows arole also for interdemic and even interspecific competition, andfor nonadaptive interdemic and even nonadaptive interspecificdivergences. He can nevertheless conclude that the enormous ad-

re are reprinted in facsimile in Wright (1986), and I give in the footnotes references togiven.

32 J. Hodge / Studies in History and Philosophy of Biological and Biomedical Sciences 42 (2011) 30–39

vances in genetics ‘have merely strengthened’ Darwin’s generalconception of the evolutionary process.6

These positionings in relation to Darwin are complemented, andindeed conditioned, especially in the review of Fisher’s book, bypositionings in relation to Fisher. Here, Wright explains thataccording to Fisher natural selection causes evolution most effec-tively when a large interbeeding population is changed throughoutby the uniform selective accumulation of the same small random,inherited differences, by, that is, so-called mass selection. Wrightidentifies this, Fisher’s conception of evolution, as ‘pure Darwinianselection.’7 Wright sees Fisher as closer to Darwin than he is himself,because in Fisher’s optimal evolutionary scenario there is not thestructure of subpopulations that there is in his own SBS. Conversely,Wright sees himself broadly in descent from Darwin, and departingfrom that heritage only in so far as his new SBT has natural selectionworking within a populational structure not recognised as optimalby Darwin and Fisher.

If we ask next whether Wright at this time saw himself joiningin something one might call a New Synthesis in evolutionary biol-ogy, such as Julian Huxley will announce in the late 1930s andearly 1940s, and that will be reaffirmed after the Second WorldWar by Ernst Mayr and his allies, then, not surprisingly, the answeris that he did not. What he does do is to emphasise, especially inthe Fisher review, that he and Fisher (along, too, with J. B. S. Hal-dane) are at one in seeking to advance the statistical understandingof evolutionary causation pioneered by Darwin, and to do it byworking out, mathematically as far as possible, the populationalconsequences of twentieth-century Mendelian genetics. Any posi-tioning of Wright in relation to Darwin or indeed any other author,school, tradition, doctrine or whatever may therefore often be clar-ifiable by looking to Wright’s agreements and disagreements withFisher.

There is one caveat to go with this reflection: we can not com-pare and contrast their views as evolutionary theorists by compar-ing and contrasting their mathematical analyses of populationgenetics. The reason is worth making explicit. In their mathemat-ics they had worked successfully at reaching agreement in all theirquantitative conclusions, despite differences in mathematicalmeans and methods, Wright using his own path analyses forexample, as Fisher obviously did not. As Wright explained earlyin his Fisher review: the central problem in the analysis of the sta-tistical consequences of heredity is determining the distribution ofgene frequencies under the pressures of mutation, selection,migration and so on, and as affected by population size. Under gi-ven conditions what proportion of the genes will be fixed? Howmany will have frequencies around 50%, how many around 99%?How rapidly will new mutations reach fixation under favourableselection? Now, Wright is keen to go on to bring out how thor-oughly he and Fisher are in agreement about the mathematical re-sults they have reached concerning these questions. Their resultsare, he says, now in ‘complete agreement as far as comparable,although based on very different methods of attack.’ With thatpoint made explicit, Wright goes on to dwell on their disagree-ments over the biological interpretation of evolution, and on thedifferences between Fisher’s pure Darwinian mass selection sce-nario and his own SBS.8

As we turn, now, to the structuring of Wright’s 1931 paper, weneed always to bear in mind this distinction, between mathemat-ical agreement and biological disagreement, all within a commoncommitment, by Wright and Fisher, to continue, with the newMendelian resources, the project that, as Wright saw it, Darwin

6 Wright (1931b), p. 155.7 Wright (1930), p. 83.8 Wright (1930), pp. 81 and 83.

had started: understanding evolutionary causation statisticallyand indirectly, not directly and physiologically. The paper startswith that short introduction on the state of evolutionary theory,where Wright makes those points about Darwin’s theorising. Thencome two long sections of mathematical populational genetics, thefirst on the variation of gene frequency, the second on the distribu-tion of gene frequencies and its immediate consequences. It isobviously on what happens in these two sections that Wright re-ports, in his Fisher review, agreement with Fisher on derivationalresults. Only in the third and final section, of less than a dozenand a half pages, does Wright eventually do any evolutionary theo-rising, now writing under the telling section title: ‘Evolution ofMendelian systems.’ And it is there that he develops and defendsthe SBT, with no overt reference to Fisher, but mindful throughout,we can be confident, of his agreements and disagreements withFisher’s conclusions about the optimal causation for evolution.

This caveat about how to understand relations between thesetwo men as evolutionary theorists should be complemented byrecalling that the legends of their antagonism in later years are lar-gely true; but also by insisting that what is far more instructive, forour purposes here, is that for a full decade, from their first discus-sions in 1924, they corresponded often, were on good terms per-sonally, and were expressly, in public and private, full of mutualadmiration, and keen to work at agreements as much if not morethan disagreements; and that when they disagreed they bothsaw Haldane as sometimes holding intermediate, even reconcilia-tory, views. Unlike Wright, Haldane did often deploy the term Dar-winism in positioning his own views in relation to those of others.This tactical habit was especially adopted when, as Haldane man-ifestly revelled in doing, he went out of his way to confront andconfute religious opposition to Darwinian legacies. Significantlyperhaps, although not a Christian as Fisher was, Wright was likeFisher in not joining Haldane in such confrontational and confuta-tional stances.

My paper here will return before it closes to both those big la-bels: Darwinism and the New Synthesis; but it should be clear thatright now there is no need to clarify them further in what comesnext: namely an attempt to understand how it was for Wright inthe 1920s and early 1930s, especially how it was for Wright assomeone who certainly saw his SBT as a synthetic achievement,at least in the mundane sense that the work leading him to thisSBT was often putting together what had not been integrated be-fore. On Wright as a synthetic thinker, in this mundane if not banalsense, the main points are now familiar in the literature on his lifeand work. First, he moved from student days on in circles, espe-cially at Harvard, where Darwinism, Mendelism and Biometrywere seen as consilient not as conflicting; the contrast with Fish-er’s Cambridge upbringing being plain. Second, well before comingto the views on evolution that he first published in full in 1931, hehad been pursuing several diverse lines of scientific inquiry in suchfields as physiological genetics, animal breeding strategies, pathanalysis and econometrics. Third, he had also developed, by thecompletion of graduate school, two comprehensive intellectualcommitments that are more philosophical than scientific. One ishis general theory of all natural, indeed all causal, science as thestudy of conservationary (or homogenising) and innovationary(or heterogenising) causes of change in physical, biological and so-cial systems, his general theory of change. The second is his dualaspect panpsychist view of mind and matter, which holds that lifeand mind go all the way down from humans to electrons, albeitvery attenuatedly, and that mind is prior to matter, in that even

J. Hodge / Studies in History and Philosophy of Biological and Biomedical Sciences 42 (2011) 30–39 33

bodies are really mental although they can only appear to ourminds as material.9

Suppose, then, that we are seeking to see how all these ele-ments in Wright’s early intellectual development did or did notfeed into his original rationale for his shifting balance theory(SBT) of evolution. What lines of interpretative inquiry should webe pursuing as Wright’s historians? The answer has to be that allkinds of lines will be worth following. The present paper can onlyhope to explore the promise held out by a few such lines, whilemerely pointing toward some of others.

2. The shifting balance theory (SBT): the question and theanswer

Going back now to Wright’s shifting balance (SBT) answer to thecentral evolution question: there are three steps we need to takenext in preparing to understand the original rationale for Wright’sgiving this answer to this question.

First: we need to accept, as Wright has emphasised and othershave confirmed, that the SBT originated as his extrapolationaryprojection onto nature in the wild and the long run of his prior con-clusions about optimum breeding strategies on the farm. The prin-cipal issues can be recalled here in very brief summary.10 From hisHarvard mentor Castle’s work on selection in hooded rats and fromhis own doctoral work on guinea pigs, Wright was early convincedthat mass selection of individual traits is often efficacious but alsonot reliably optimal. From his later USDA breeding experiments,Wright confirmed that inbreeding leads to a decline, but also in-creases random differentiation among lines and can fix distinct traitcombinations; while, from studies of animal breeding histories, hebecame convinced of the advantages of combining selection withinbreeding within herds, followed by the crossbreeding consequenton exporting of sires from superior herds to others, with eventualoptimal benefits to the whole breed, the optimum breeding theory.

Second, we do indeed need to concentrate not on Wright’s shortpaper of 1932, but on his long paper of 1931. Especially we need toconcentrate on the last 16 pages of 1931, because it is uniquelythere that Wright explains how he sees the SBT as an account ofhow the appropriate balance of homogenising and heterogenisingcausal factors (recall the general theory of change mentionedabove) makes both change on the farm and change in the wild opti-mal and intelligible.

Third, we need to move to Wright’s panpsychism, only when wehave got clear about the relations between SBT and general theoryof change. The reason for doing so is because the panpsychism hasno bearing directly on the SBT; it only has relevance through thegeneral theory of change, and that bearing will be seen to be morepermissive than directive.

The first of these steps will be taken as read from now on in thispaper. It is the second and third which will be argued for in whatfollows, and in that order. Let it be agreed at the outset that thetwo papers, 1931 and 1932, do make the same proposal. For bothend by asking that same question about when, to put it crudely,does evolution go quickest, most continually and most irreversibly;and they both give the same answer: namely, with the SBS, theshifting balance scenario. However, there are crucial differencesbetween the two papers, and they are all such as to make the 32(to abbreviate) paper a very misleading place to start in any effortsto understand the original rationales Wright had for giving that an-swer to that question. To take two obvious differences: 32 does nottalk at all about the roles of homogenising and heterogenising cau-

9 Hodge (1992), Provine (1986), Ruse (1996) and Steffes (2007).10 Hodge (1992), pp. 265–268. This paper is reprinted in Hodge (2009).11 Wright (1931b), pp.147 and 163.12 Provine (1986), pp. 271–275.

sal factors, whereas 31 makes that whole theme decisive for whatWright sees SBT achieving intellectually; and, again, 32, unlike 31,deploys adaptive landscape analogies and models as expository de-vices. We have to see, then, just how it is the joint effect of thesetwo contrasts that makes 32 the wrong entry text for Wright’s his-torians. And, to appreciate the full implications of concentrating on31 and not 32, it is crucial to recognise, albeit in a summary way,four challenges emphasised by Wright in understanding the causa-tion of evolution. Here are the four challenges in summary and slo-gan form.

A. Mutations by themselves are hopeless as causes of evolution,being now known to be almost all small in effect, rare, recessive,random, and often disadvantageous. What else therefore do weneed to figure in, apart from mutations, to get an adequate theoryof the causes of evolution? This challenge is such a comprehensiveand fundamental one that we may call it here the whoppingchallenge.

B. Biparental, sexual reproduction, because it includes recombi-nation, is excellent at generating new gene combinations includingtherefore new and better gene combinations; but, here is the badnews, it is very effective too at going on to chop up those combina-tions, including the best ones. How then can evolution be under-stood as it proceeds in higher animals that only do sexualreproduction, and no asexual reproduction? How is such evolutionin higher animals intelligible given both the good news and the badnews about sexual reproduction: the chopping challenge.

C. In very small populations, genetic change slows, even stops,when the distribution of gene frequencies settles to a stagnantequilibrium, and it may anyway lead to populational extinction.It slows likewise in very big populations too, without extinction.Change goes on with the least tendency to stop in intermediatesize populations, or even better in a large population broken upinto small subpopulations (the shifting balance scenario): the stop-ping challenge.

D. One way for change to come to an equilibrial stopping is duepeculiarly to selection. For selection takes the population up to thenearest adaptive peak and holds it there, not at the highest peak onthe adaptive landscape. How can other factors than natural selec-tion, random drift especially, counteract this imperfection in theworkings of natural selection, so that the population can go on tohigher and higher peaks? The stopping-by-topping (or topping forshort) challenge.

So much for a swift glance at the four challenges. When wecheck on 31 and 32 we see that A (whopping) and B (chopping)and C (stopping) feature prominently in 31, but D (topping) doesso barely at all, at least not in the precise way it does in 32; whileC (stopping) and D (topping) are both prominent in 32 but A(whopping) and B (chopping) are not. This absence in 32 of B(chopping) is striking because it is solving this chopping challengewhich is said in 31(ESP 147) to be the purpose of that whole paper;while in 32 (ESP 163) it is D, the topping challenge, that is calledthe problem for evolutionary genetics.11 Once we see this doubledifference between 31 and 32, two thoughts are unavoidable. First:Is there evidence that Wright only came to see the topping challengeat centre stage after writing 31? Yes, there is, and it seems that cor-respondence with Fisher helped at least to get Wright to do so.12 Isthis important though? Well, it surely is, because it is the wholeapparatus of adaptive landscapes, with drift across adaptive valleys,that 32 invokes as the answer to the topping challenge. So, it seemsthat developing that apparatus was a very recent, new move madeby Wright to go with the new preoccupation with the topping prob-

34 J. Hodge / Studies in History and Philosophy of Biological and Biomedical Sciences 42 (2011) 30–39

lem. Second: Wright’s resolution of B, the chopping challenge, in 31invokes not drift but inbreeding as countering meiotic chopping.Plants he points out do sexual and asexual reproduction, and plantbreeders take advantage of this: they use sexual reproduction togenerate lots of gene combinations, and then use asexual reproduc-tion to preserve and perpetuate the good combinations, and to pre-vent more sexual reproduction from breaking them up. So, reflectsWright, one has to ask how is evolution intelligible—Wright’sword—in higher animals with no asexual reproduction. Indeed, hesays, this is the question his paper is all about. Well, when is sexualreproduction least unlike asexual reproduction? With inbreeding.And animal breeders have unknowingly been exploiting this for along time. So, that is mainly why in 31 Wright needs small subpop-ulations; it is to ensure inbreeding; and they must be small subpop-ulations not just small populations because a single small populationon its own can only do slow evolution and tends to extinction any-way. In this way, then, 31 is closer to Wright’s original thinkingabout evolution than 32, closer in its formulation of its principalproblems and solutions.

We should reckon, therefore, that Wright—in 1924-5, when hefirst applied his optimum breeding theory to understanding evolu-tion—originally wanted the population structure of SBT, not be-cause he wanted drift as an answer to the topping problem, butbecause he wanted inbreeding as an answer to the chopping prob-lem. Indeed, although no smoking text confirms this conjecture di-rectly, it surely has to be roughly right; if only because, once again,the chopping challenge, as resolved with inbreeding, is involvedwith Wright’s early work on the optimum breeding theory as stop-ping by topping, as resolved with random drift, was not. So, in sum,Wright eventually became a famous drifter, but he may have cometo emphasise drift years after he was first emphasising inbreeding.His original reasons for embracing SBT were, it could well be, muchmore to do with early engagement with the challenges he resolvedwith inbreeding, and much less to do with the problems he wouldlater resolve with drift; although, obviously, he was always veryaware that small population size always entails both inbreedingand drift.

We will be moving next to Wright on heterogenising andhomogenising causal factors. There are some telling passages scat-tered through his later papers that can help prepare us in makingthis transition. Worries about anachronism, hindsight and mis-taken memories need not worry us, as the implications of thesepassages can be—and indeed most have been—confirmed in bio-graphical study of the early years.

From graduate school on, Wright once recalled, his main ‘exper-imental project’ was studying gene interactions especially in theheredity and development of guineapig coat and eye colours. Thisconcern with these gene interactions, so central to all Wright’swork in physiological genetics, gives the link with what he tellinglycalls, in contrast with anything experimental, his ‘speculations onevolution.’ These speculations were ‘dominated from the first bythe thought that there must somehow be selection of coadaptedinteraction systems as wholes.’ The difficulty, he continues, wasthat, with sexual, biparental heredity, the reduction division‘breaks up combinations so rapidly’ in geologic time; so that withpanmixia natural selection can operate only on the average effectsof genes in all their combinations. The link with balances betweenheterogenising and homogenising factors was spelled out mostclearly back in the late 1930s. Recalling again the theme that whatis optimal in plant breeding is a balance between alternations ofsexual, biparental and asexual, uniparental reproduction, he saysexplicitly that it is likewise with a purely sexual species: what is

13 Wright (1982), p. 625 and Wright (1939), p. 328.14 Everything said here about Fisher is documented in Hodge (1992).

optimal is the best balance between alternating inbreeding andoutbreeding; and this ‘balance’ between ‘the two systems’ can beprovided, he concludes, by subdivision of a population into localinbreeding races with occasional intermigration. This arrangementis, of course, what we have called here the SBS. In higher animals inthe wild, then, the shifting balance scenario is nature imitatingfarm animal breeders who are imitating, as best they can, plantbreeders.13

This balance is no less obviously one between inbreeding as(like uniparental reproduction) homogenising, and outbreedingas (like biparental reproduction generally) heterogenising. It is afair biographical guess, therefore, that this was for Wright the ori-ginal case of this comprehensive theme of balance between factorsmaking for persistence and factors making for change; and thatthis case arose originally and directly from engagement with whatwe are calling the chopping challenge. Note, too, that it is no less acase of his engagement with the whopping challenge, arising fromthe hopelessness, as causes of evolution, of the persistence andchange factors at the very lowest level of organisation: gene dupli-cation and gene mutation. For, as Wright constantly emphasises,both the whopping and the chopping challenges can only be metby figuring into any theorising, about cumulative evolutionarychange over long periods, what is going on at several levels upfrom the lowest level; by figuring in, then, what is going on atthe level of gene combinations in organisms, or of inbreeding indemes and so on. Mere extrapolationary extension over time ofwhat is happening to genes, or indeed to individual organisms, willnot meet those challenges; one has to come to the horizontal is-sues through an integration of our knowledge of balances betweenpersistence and change at several higher levels in the vertical hier-archy of organisation, especially demic and other populationallevels.

3. Homogenising and heterogenising causes

Before focussing more closely on Wright’s account of the shift-ing balances between homogenising and heterogenising causes, itwill be worth glancing at the contrast with Fisher.14 For Fisherworks, albeit usually more implicitly, with a categorising of causesthat is deeply unlike Wright’s. For Fisher, the fundamental divisionis between entropic causation and counterentropic causation. Withone exception, all physical causes whatever are entropic: that is, dis-ordering, moving systems from less to more probable states. The oneexception is only at work in the living world, and it is natural selec-tion. To get a sense of how significant and consequential was thiscontrast between Wright’s and Fisher’s categorising of causes, it willhelp to glance at how this contrast correlates with other contrastsconcerning considerations of optimality.

One reason it will help to do this here is that we can correct animpression given by Wright’s own contrast between his shiftingbalance scenario and Fisher’s large, freely crossing population withmass selection scenario. Naturally enough, Wright compares andcontrasts his and Fisher’s two scenarios as if they were offered asdifferent answers to the same question: namely, his, Wright’s, cen-tral evolution question. But any examination of the two theorists’writings will show that the question Fisher was answering wasnot at all the same as Wright’s central evolutionary question. Fish-er was not even answering a question about evolution in generaland as such, but rather one about natural selection: namely, underwhat conditions is natural selection best able to counter the entro-pic, degenerative tendencies within any species, and best able toallow the species to adjust most successfully and adaptively to

J. Hodge / Studies in History and Philosophy of Biological and Biomedical Sciences 42 (2011) 30–39 35

what are, for the species, always deteriorational changes in theenvironment.

To appreciate the wider implications of this contrast betweenFisher and Wright’s central questions, we might explore variousother contrasts in their lives and works. But just one such contrastis especially pertinent here. Wright was Goldilocks thinker. (Goldi-locks was the little girl who always finds what she wants withintermediates, away from extremes, not too hot, not too cool andso on). By contrast Fisher was a Goldwater thinker. (Recall the sen-ator from Arizona who said that extremism in defence of what isright is no vice, and moderation no virtue). With that stereotypingin mind, we may consider again the chopping challenge in 31; forwe can now bring into focus a fundamental point of contrast be-tween Fisher and Wright over what is optimal.

Fisher thought not just that natural selection is the only opti-mising cause in the universe because it is the only counterentropiccause; he thought that sexual reproduction with Mendelian partic-ulate heredity, with small, rare mutations and large, almost drift-less, randomly mating populations, is the most perfect casualcomplement to natural selection; and that is indeed why this sce-nario is Fisher’s alternative to Wright’s shifting balance scenario.On Fisher’s view, a big population is optimal for the counterentro-pic workings of natural selection, because with a big populationthe entropic processes of drift and mutation, that counter the goodwork of selection, are at the lowest level consistent with selectionbeing able to optimise its effects; for drift will be very slight in abig population, and mutation rates can be very low and still ade-quate to provide material for selection across the whole species.Any notion that sex or selection themselves have inherent limita-tions, imperfections so basic that our evolution theory must ex-plain how evolution can go well despite these imperfections, isnot a notion that was ever likely to occur to Fisher left to himself.By contrast Wright’s theorising in 31 and 32 is focussed on resolv-ing two challenges—the chopping challenge and the topping chal-lenge—that arise from his seeing sexual reproduction and naturalselection, respectively, as imperfect, suboptimal in what theymay, under certain conditions, contribute to the causing ofevolution.

We will return later to these contrasts between Fisher andWright, but before doing so we need to look further at the rationaleand sources for Wright’s categorisation of evolutionary factors. Asfor that categorisation itself, it is worth considering how unmo-mentous it can well seem. After all, to note that recombination isheterogenising in that it makes for variation, while linkage is a fac-tor making for homogeneity; this is to note the obvious; and tonote that some factors, such as selection, are intrapopulationallyhomogenising but interpopulationally heterogenising is againobvious. Indeed no historian of Wright’s intellectual developmentneeds to disagree here. For what is not banal are not the categori-sations as such, but the motivation for grounding the SBT in anysuch division of factors into the conservative and innovative.

What emerges from any survey of all his general reflections onscience is that Wright, from graduate school on, had a comprehen-sive view about what causal science aims for and how it gets there,a view he probably owed especially but not solely to the teachingsat Harvard of Lawrence Henderson.15 All the different causal sci-ences are concerned with understanding equilibria, because all sci-ences try to understand the causes of change, and changes areonly intelligible in so far as they are in some way equilibrial or tend-ing to the equilibrial. Where there is no change, obviously no theoryof change is needed. Where, at the other extreme, change is totallyinnovative, and without any conservation or persistence, no theory

15 Ruse (1996), pp.380–383 and 403–404.16 Wright (1931b), pp.143–154.

is possible. Intelligible processes are therefore understood whenwe understand the balance in them of innovation and persistence.Homogenising factors are those that make for the synchronic unifor-mity or for diachronic persistence of entities or properties and so forsameness and constancy, while heterogenising factors do the oppo-site. Any system undergoing intelligible change will have both atwork in it, and we understand those changes only in so far as weunderstand how neither kind of factor puts the other out of business,and understand how therefore they are balanced enough to maintaina moving equilibrium, and so neither a coming to a halt or, con-versely, an escalation into unintelligibly rapid, disorderlytransformations.

There is more to Wright on this theory of change in general thanwhat has just been set out, but even this much allows to see thatwhat is going on in 31—and is not really visible in 32—was forWright a special case of what a great deal of natural and social sci-ence is all about. Notice for a start some of his terms. Not only is hisleading conclusion, SBT, a conclusion about a balancing, a movingequilibrium, arising from the interactions of homogenising andheterogenising factors; he says that we can appreciate how naturalselection can be sometime heterogenising and sometimes homog-enising, according to conditions, only if we view evolution itself asa ‘moving equilibrium.’ And obviously enough a moving equilib-rium is what he will later call a shifting balance. Again in talkingof this moving equilibrium view of evolution he talks of homogen-ising and heterogenising factors as, in another pair of terms, con-servative and radical, thus bouncing off traditions in politicaltheory that look for progress through changes in balances. Intelli-gible is Wright’s own term, as too is his talk of intermediate de-grees of ‘plasticity,’ the intermediate condition between nochanges at all and unintelligibly fluent change. The plasticity pointhe connects with the breeders’ talk of molding a herd like clay, aherd whose heredity is, with the SBS, intermediate in its plasticity,as clay is between frozen mud and flowing, unmoldable muddywater. So what makes it possible to understand a change is alsowhat makes it possible to control it reliably and predictably. Thereis the requisite balance of homogenising and heterogenising fac-tors. Again, Wright says that a species is like an organism, in thatan organism only thrives as long as it is constantly reequilibriating-ly shifting in its successive balances, and so likewise a speciesevolves best when the heterogenising and homogenising factorsare in the proper reequilibriating balances.16

Almost all that we have just reviewed can be confirmed just byreading the 31 paper, but what we can now do is to relate theseWrightian themes to themes in Herbert Spencer. Note for a startthat, as Lotka says, in his 1925 book on physical biology (a book ci-ted by Wright in 1931), it was Spencer who had made movingequilibrium a catch phrase. So, Spencer is responsible for the veryname of SBT, Wright’s later variant on his 31 use of the movingequilibrium phrase; and Spencer is responsible too for the ratio-nale for SBT as a moving equilibrium theory. A caution needs tobe recorded here. What Spencer says, in his First Principles, and inhis Principles of Biology, about the distinctive properties of movingequilibria, does not match up exactly with Wright’s use of theterm. For Spencer the decisive difference is between a rock restingon the ground, as a case of static equilibrium, and a spinning topowing its balance to its motions, as a case of a moving equilibrium.What is distinctive for Wright about a moving equilibrium, or shift-ing balance, is that the balance between the balanced factors islightly balanced enough, sufficiently finely poised (his word), toreadily allow change on to another balance, in a rebalancing ofthe factors making for homogeneity and heterogeneity. In taking

36 J. Hodge / Studies in History and Philosophy of Biological and Biomedical Sciences 42 (2011) 30–39

this view Wright is not echoing exactly the precise way Spencermakes his distinctions among equilibria, but he is broadly echoingSpencer’s view of how an organism’s continued life in a changingenvironment depends on its constantly rebalancing its successiveinner equilibrations. As for Lotka on moving equilibria, again Lotkadeparts from the Spencerian distinctions themselves even whileacknowledging the precedents they have set for his explicationsof what a moving equilibrium is; and it is Lotka’s explications thathave since been followed up by economists and other social theo-rists since.17

To see that these echoes of Spencer in Wright are no mere mat-ter of words and phrases, one needs to stand back and take in somelarger issues; for we need to see how the thermodynamics of Fish-er’s hero Boltzmann—Darwin was his only other top hero in naturalscience—had constituted a direct challenge to Spencer’s most gen-eral generalisation of all. Recall that Spencer’s most general gener-alisation, his universal law of evolution, said that all systems—whether societies, organisms or nebulae—tend (just because allcauses have multiple effects) to move from homogenous states toheterogenous ones, these being Spencer’s own terms. Think of dif-ferentiation in growing embryos or nebular condensation in theheavens or increasing division of labour in advanced societies.Spencer’s original preoccupation with homogeneity moving alwaysto heterogeneity traced decisively if not exclusively to his readingabout Karl Ernst von Baer’s views on comparative embryology,views von Baer had himself seen as consilient with the philosopherSchelling’s concerns with nature’s upward movements from mat-ter and the massive to form and the individual, concerns encour-aged by Schelling’s early study of the late Greek PlatonistPlotinus. Where Spencer went beyond these antecedents was inascribing the universal differentiationary tendency to the persis-tence of force, subsequently reinterpreted as the conservation ofenergy. In doing so, Spencer—as Beatrice Webb would later ob-serve—had the bad luck to construct a theory of everything justafter the first law of thermodynamics was announced in the1840s (the good news: energy is conserved), but before the secondlaw was announced in the 1850s (the bad news: the energy avail-able for work in any closed system decreases). In the final decadesof the nineteenth century, with Boltzmann’s statistical interpreta-tion of the second law, it became even more obvious that the Spen-cerian doctrine was becoming difficult to uphold. In any closedsystem, Boltzmann said, the tendency is from heterogeneous tohomogeneous states. So, at least for the physical world, if not theliving and the social, Spencer had it the wrong way round.

Consider next what Fisher did on this big issue. As an under-graduate he seems to have been a one worlder: natural selectionor something like it is at work among stars no less than organismsand is making for progress rather than degeneration. But Fisherhad a postgraduate year with James Jeans, a high priest of thenew Boltzmannian thermodynamics; and after that, and certainlyby 1930, and after reading Eddington, Fisher is a two worlder, ormore precisely has a two way universe. Boltzmann is right aboutthe way down; entropic decline rules everywhere. The only excep-tion is the living world which thanks to natural selection (the onlycounterentropic cause in the universe) is always on the way up,going from more probable to less probable states, in exact opposi-tion to the physical world which goes from less to more probablearrangements. (Civilisations, Fisher holds, tend to decline, todegenerate also, socially, but eugenic intervention can counterthat).

How does Wright’s thinking map onto all these options? Henever says so directly in one place, but if we piece together the rel-

17 Lotka (1925). On Spencer’s importance for Wright the pioneering treatment is in Ruse18 Wright (1931a), p. 89 and Wright (1948), p. 538.

evant passages in several places his position is pretty clear. He goeswith neither Spencer nor Boltzmann-Fisher. Instead of holdingwith Spencer that all systems go from homogeneity to heterogene-ity, or holding with Boltzmann that all physical systems at least gofrom heterogeneity to homogeneity, he says that what they all do—whether physical, organic or social—is to have both tendencies al-ways going on in them. There is then just one kind of ordering: thephysical, the organic, the social are all in one world order for allhave both of those two tendencies. And so all causal scientific the-ory—physical, organic and social—is the study of how those twotendencies do or do not balance each other, or rather how theydo, because a system doing only one of these tendencies is notan object of such inquiry being either too rigidly frozen or toowildly fluid. The relevance to what Wright saw himself achievingwith the SBT should now be plain. The 31 paper is presented asan exemplification of this third option: seriously-modified-Spence-rian natural philosophy of change, but without the direct opposi-tion to Boltzmann’s position that is in Spencer himself; although,obviously, with plenty of conflict with any Boltzmannian positionsuch as Fisher’s.

We will be passing shortly to Wright’s panpsychism, but beforedoing so we need to discuss three complications in Wright’s rela-tions with these Spencerian and Boltzmannian issues. For a start,we need to watch Wright opening his short 1931 paper, on ‘Statis-tical Theory of Evolution’ in the Journal of the American StatisticalAssociation, by reflecting on Fisher’s comparisons and contrast be-tween evolution in biology and the second law of thermodynamics.Both concern irreversible processes that mark a direction of timeand both conform to statistical laws, Fisher has emphasised. But,Wright also reports, Fisher sees a basic contrast: evolution goesfrom lower to higher levels of organisation, and from more proba-ble to less probable states, while the entropic tendency runs theother way. Wright does not agree or disagree here, but he contin-ues by sketching three options: first, that ‘evolution is a mere eddy’in the general running down of the universe; second, that, on thecontrary, ‘the developmental side of nature so conspicuous to biol-ogists is an aspect of reality more basic than increase of entropy inphysical systems;’ third, that time is without any direction oneway or another. Deciding among these three options is a philo-sophical task that he will not undertake, he says, accepting thatas with entropy so with evolution: statistical theorising is the onlyway to better understanding. And he then moves on to biologicalevolution. Now no known smoking text allows us to be sure asto which of these three options is closest to Wright’s own. How-ever, the phrasing here, and a cryptic closing to a later EncyclopediaBrittanica piece on evolution, strongly suggest at least that the sec-ond is closest. Certainly the talk of a mere eddy seems to be a dis-tancing move. Notice, too, that he ascribes the first option to thephysicist Eddington and the third to the chemist, G. N. Lewis; whilethe second is identified more with what comes naturally to biolo-gists, people like himself he seems to be saying.18

Next: we need to be cautious when we seek some general sum-mative formula in contrasting Fisher and Wright. It may be tempt-ing to categorise them as an English Darwinian and an AmericanSpencerian, and so as one more case of Darwin having more follow-ers in his own country, while Spencer has more across the ocean.But, it is surely more accurate to label them both as Darwinians,with the English one labelled a Boltzmannian Darwinian and theother, the American, a neo-Spencerian Darwinian.

We need also to be clear about how far Wright has departedfrom Spencer, in no longer privileging heterogenising tendencies,in rejecting Spencer’s Lamarckism and also on the central evolution

(1996), pp. 379–384.

J. Hodge / Studies in History and Philosophy of Biological and Biomedical Sciences 42 (2011) 30–39 37

question itself. For Spencer, the evolution of life and of society wasreversible, indeed inevitably so in the long run. For Wright, all evo-lutions are essentially irreversible and hence cumulative changes.This stance, shared with Lotka and others with an eye on thermo-dynamics, Wright may well have owed to physicists. For Wright itwas a quite general stance. Writing later in his life, under the head-ing ‘Evolution in General,’ he briefly suggested that the irreversible,cumulative evolution of culture is independent of Mendelianheredity, but that here too it is the balance of persistence andchange that makes evolutionary change intelligible. Here, indeed,the process goes best with a subdivided social structure with cul-tural isolation and cross-communication kept in proper balance:in a word a social shifting balance scenario.19

We may say of Wright that his biological evolutionary theory isplaced between physical theory and social theory, between physi-cal and cultural irreversibilities, because ultimately his biologicaltheory is worked out to conform to principles common to all suchattempts to understand the roles in shifting balances between fac-tors for change and persistence. At least, then, it does perhapstransform our view of Wright’s shifting balance theory, surely asinfluential as any genetical theory of evolution science has yet gi-ven us, just to recognise that it was given that name by its authoras a variant on a Spencerian phrase, ‘moving equilibrium;’ and per-haps recognising this can transform, if only just a little, our pre-sumptions about how biology in the twentieth century hasdrawn on its authorial ancestors and conceptual antecedents inthe nineteenth century.

4. Roles for the panpsychism?

Where then does the panpsychism come in? That is the view,held as Wright knew, by Leibniz and Wundt to name but two,and adopted by Wright in graduate school—that mind goes allthe way down from us to electrons, and that matter is just theway those minds appear to our minds, mind being then the moreultimate of the two aspects of reality: mind (the inner aspect)and matter (the outer).Wright always insisted (see in 1931) thathis commitment to this metaphysics did not effect his science.20 Ionce thought he was wrong to say that. The wording of his 32 paper,in talking of control by natural selection, and in talking of randomdrift as freeing the population to go higher adaptively and so on, re-minded me of Wright on free will, on the side of mind in an individ-ual human agent; for it reminded me of Wright’s view that thismental freedom of choice, will and action in a human individual, de-pends physically on systems with very plentiful feedback mecha-nisms and very sensitive amplifying mechanisms allowinginfinitesimally small physical changes to have indefinitely large ef-fects.21 I now think that such parallels are not signs of influence.For Wright, any system may tend to get stuck going nowhere andthen later be caused to be moved on to new states. And, as he saysmany times, causation in the physical world is the analogue of willin the realm of mind; or, more precisely, causal determination,including probabilistic or statistical determination, in the observedphysical world is how the deeper mental determination (choosingand willing) appears to us.

So, to think that Wright’s SBT talk—about controlling actions byselection being countered by random drift—is somehow directlyrequired or dictated by his panpsychism can be misleading; andit is so for two reasons. First, to seek a connection between theSBT and the pansychism in this particular way is to make, once

19 Wright (1951), p. 596.20 Wright (1931b), pp. 155–156, Provine (1986), p. 96. For Wright’s panpsychist views,

(2007).21 Hodge (1992), pp. 275–277.22 Wright (1931b), p. 147.

again, the mistake of privileging the 32 paper and its concerns withthe topping problem. Second, it is to overlook what Wright himselfpoints to, in the 31 paper, as his own view of how the connectionmight be made. As he insists, in the passage sketching his panpsy-chism and his view of free will, in the 31 paper, his account of thephysical world, and of our scientific theories about it, is mechanis-tic, even deterministic, where determination includes probabilisticdetermination; and if there is a physical analogue of free will it isnot found in causes and effects of changes in species or popula-tions; but in the adaptability of individual organisms. By individualadaptability, Wright indicated a property of organisms that he as-sumed to be recognised by geneticists generally, and so not a prop-erty he alone was claiming to acknowledge. The property arisesbecause genotypes do not determine phenotypes in a one to onedetermination; for any one genotype can have many different phe-notypes in various conditions; and, conversely, various genotypescan give rise to the same phenotype. So, Wright suggests, if oneis looking, for the locus of what is metaphysically seen as freedom,not in human actions, but in the processes of evolution as under-stood scientifically by the SBT, then that locus is in the evolution-ary consequences of the physiological genetics of this individualadaptability. For, he says, the entities above the individual organ-ism in the organisational hierarchy—populations and species andso on,—are not intricately enough organised physically to bejudged, metaphysically, to have minds and so freedom in theiractions.

Now, he had already explained that, thanks to individual adapt-ability, selection can not be completely homogenising, nor there-fore completely determining and controlling, in its populationaleffects; because individual organism adaptability ensures thatenvironmental selections among phenotypes do not entail one toone determinations of selections among genotypes. The decisivepassage has been alluded to more than once already; but it willbe worth quoting here more fully, because it throws such indis-pensable light on how Wright’s general theory of change, and soof causal science, intersected with his panpsychism. Environmentalpressure, that is selection pressure exerted by the environment, ‘onthe species as a whole’ is, he says a ‘factor of homogeneity’. But it iswrong to say that, because natural selection reduces variability,especially by eliminating extreme variants, ‘it cannot be the guid-ing principle in adaptive evolution.’ He explains that from ‘theviewpoint of evolution as a moving equilibrium . . . the guidingprinciple can be found on the conservative as well as on the radicalside.’ The value of any selection coefficient depends on ‘the bal-ance’ between environmental pressure making for homogeneityand individual adaptability making for heterogeneity. High devel-opment of individual adaptability allows ‘survival of genetically di-verse types in the face of severe pressure.’ He might have addedhere, what he had emphasised already: that past selection oftenwill have favored more adaptive over less adaptive individuals,so that its controlling and determining action at any time is limitedby the consequences of its past effects. Here, then, the prospect ofany stopping of evolution due to selection making for stagnantequilibrial homogenisation is implicitly countered, by consideringhow selection and individual adaptability interact, so as to makefor continued, moving equilibria, constant reequilibriations, thanksespecially to the factor in evolution which is the locus of freedommetaphysically considered.22

Having concluded his philosophical excursus in his 31 paper bytracing freedom in evolution, metaphysically considered, to indi-

see Hodge (1992), Ruse (1996) and, for much the most extensive treatment, Steffes

38 J. Hodge / Studies in History and Philosophy of Biological and Biomedical Sciences 42 (2011) 30–39

vidual adaptability, Wright closes by insisting that this is a ‘subjec-tive interpretation’ that has ‘no place in the objective scientificanalysis’. It should be clear now why he would take that line.When, as a panpsychist metaphysician, he asks where in evolutionis freedom to be located, he is indeed asking where does our sub-jective mental sense of free will find a lesser version of itself inevolving plant and animal life; and that question is not one aboutphysical causation and so not one coming within any scientifictheorising. So, it should not surprise us that the quest for unmedi-ated, direct and directive influences running from the panpsychismto the SBT yields no positive outcome. But, equally, it should alsobe clear that indirect, permissive influences, especially as mediatedby the general theory of change, do surely show themselves if webegin from the right point of departure. That point is one more in-stance, already familiar to us, of a contrast between Wright andFisher. We saw how Fisher—at least after studying with Jeans—was a two worlder; and we saw that Wright was not; for Wrightthere was always only one world, influenced throughout by twokinds of causal factors. Obviously, the homogenising and heterog-enising factors an evolutionary geneticist studies are inbreeding ormutation and the rest; while the homogenising and heterogenisingfactors a physicist studies, or again a sociologist, are quite differentfactors; it is only the contrast between the two kinds of factors thatholds across all these domains.

Now, plainly, panpsychism is a strong one world theory: thewhole point is that life, including mind—and its material, physicalcondition, organisation—goes all the way down to electrons. Thereis no discontinuity twixt social, living and physical. So, Wright’spanpsychism certainly sanctioned, even if it did not generate, hisviews of the unity of science as a unified search for the interactionbetween innovative and conservative causation in physical, organ-ic and social systems. And the panpsychism could sanction such aunified search, despite the main limitation it sets on relations be-tween the physical and the mental. According to this limitation,only very coherent physical systems have a mind of their own,Wright holds, rather than just having the minds of their compo-nents. Wright reckons that organisms are the highest systems inthe organisational hierarchy to have such coherence; so a deme,or a species or an ecosystem or indeed the universe as a whole—he is explicit about the universe—does not have a mind of itsown. So, as Wright says, he is not a theist.23

To recapitulate, then: these rapid samplings of Wright’s generaltheory of change and of his panpsychism are designed to suggest,at least, that neither of these two commitments sufficed on itsown to direct his evolutionary theorising by determining its dis-tinctive content and so the particular conclusions, especially, thatmark that theorising off from Fisher’s. What they do show, I wouldsubmit, is that the shifting balance theory was conformed to thegeneral theory of change and that this conforming was sanctionedby the panpsychism; so that if we do allow ourselves to talk ofinfluences we should have them running from the panpsychismto the general theory of change and then on to the shifting balancetheory, rather than running directly from this panpsychist meta-physics of mind and matter to the understanding of evolutionarycausation.

5. Concluding remarks

Wright’s life and work have been featured here in a very selec-tive way, with the emphasis very much on two early decades,roughly 1912–32, from his entry into graduate school to the pub-

23 Hodge (1992), pp. 273–275.24 Bowler (2003), Delisle (2009), Depew & Weber (1995), Gayon (1998) and Ruse (1996)25 Lotka (1925).

lishing of his first evolutionary papers. Anyone concentrating onthe next five decades from then on would rightly insist that variousthemes developed here may look much less pertinent when one istrying to understand the receptions and uses given Wright’s evolu-tionary theorising from then on. Were we to go on to take in thoselater decades, various detachings and lumpings would have to beacknowledged. Subsequent writings by Wright himself, and byhis supporters and critics, usually detached his shifting balancetheory from his general theory of change, and even more obviouslyfrom his panpsychism. As for lumpings, it has been routine to focuson what is common to the 31 and 32 papers: namely, their givingthe same shifting balance theory (SBT) answer to the same centralevolutionary question. A more detailed account of how thesedetachings and lumpings have proceeded could throw light onthe complexities of Wright’s later interactions with, for example,E. B. Ford and the Oxford school. But it suffices here to reiteratethe commonplace that authors often lose control of their writingsonce they are published, and that detachings and lumpings such asoccurred with Wright’s theorising are matched in many anothercase.

The value of going back to those early decades before thosedetachings and lumpings get made is obviously that we can dowhat biographical studies often make possible; and that is to bringinto the narrative and the analysis anything of any kind that seemspertinent to our understanding of how it was for our subject then,rather than how it was for others later. By being holistic and plu-ralistic in this biographical way, we can get insights, no less obvi-ously, into a whole range of issues and topics—scientific, religious,political, and so on and so forth—that are otherwise not so easilyengaged, and which can greatly enhance our more synoptic andintegrative efforts in comprehending those larger pictures and big-ger stories that concern us when we want to clarify the histories ofDarwinism, say, or the New Synthesis. Many historians—PeterBowler, Jean Gayon, Michael Ruse, David Depew, Bruce Weberand Richard Delisle, to name only a few of the more prominent—have confronted that whole range of issues and topics and shown,once and for all, that, as in the nineteenth so in the twentieth andtwenty-first centuries, there has always been more to evolutionarybiology than the mere biology of evolution.24 Familiarly enough,the most inescapable examples of this truism are found perhaps un-der the rubrics of science and religion or science and metaphysics;others—remember eugenics—come under the heading science andsociety. No less inescapably, but less familiarly, yet others belongwith those themes—the sciences and theories of order and chaos(cosmologies)—that are encountered whenever evolutionary the-ory’s relations with thermodynamics, rather than quantum and rel-ativity physics, come into play (recall Spencer, Kelvin, Helmholtz,Boltzmann or Lotka, or countless other authors, just in the decadesfrom the aging Darwin to the youthful Wright). Darwin did not seemto many people to have offered them a general theory of order. So,some went to Spencer or to Boltzmann in seeking a more completeaccount of the physical and perhaps too the social world. It is now acommonplace or should be that the Christian theist, Fisher, with hisDarwinian biology placed knowingly between his thermodynamicsand his eugenics, is not anomalous but typical. Just exactly howand how much the placings differ for Wright is no less open to dis-cussion. And, as for what was, at the time, open for discussion andwhat not: it is salutary to find an author as authoritative as Lotkawas taken to be, still, in his 1925 book, countering throughout thatdictum that Fisher was embracing: namely, the one saying that,thanks to entropic law, the physical world moves from less to moreprobable states, whereas the evolution of life runs the other way.25

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J. Hodge / Studies in History and Philosophy of Biological and Biomedical Sciences 42 (2011) 30–39 39

What historians want to do with Darwinism or the New Synthe-sis, in or out of quotation marks, depends (to echo an earlier, open-ing truism) on who and what they are and when and where:seconding scientists’ celebratory motions at centennial confer-ences or seeking sceptical, critical stances in the service of moreautonomous historians’ histories of science, or perhaps undertak-ing (if this seventies jargon is not now hopelessly passé)deconstructive analyses to make spaces for genealogies and arche-ologies replacing all possible histories. No single contributor to acollective symposium can speak for other contributors, let alonefor any wider circle of participants in these matters; but it may justbe permissible to reflect that, as many thoughtful scientists them-selves would agree, at centennial moments alternatives to celebra-tory rituals are even more timely than usual.

Acknowledgements and bibliographical points

Anyone studying Wright is massively, constantly indebted tothe masterly biography by William Provine. I am indebted too toconversations and correspondence with him. He has a paper inpreparation on the whole issue of drift from Wright to Kimurawhich will require reinterpretations of many issues and authors.Michael Ruse’s book, Monad to Man, opened up the Spencer-and-Wright relationship. I am often drawing on that book here andhave many debts to discussions with its author. Over the years, Ihave learned way too much to be acknowledged summarily in talk-ing with my Leeds colleague John Turner. David Steffes’s recent pa-per argues for Wright’s panpsychism being an influence on his pathanalyses. Even not-fully-persuaded readers can garner a great dealfrom his valuable paper. I wrote earlier on Wright and Fisher, theirscience and their philosophy, in the volume edited by Sahotra Sar-kar on The Founders of Evolutionary Genetics. That paper of mine isnow reprinted in a collection of my papers, Before and After Darwin.As explained in the present paper, I now take a different view ofthe relations between Wright’s panpsychism and his evolutionarygenetics.

Wright’s unpublished papers are at the American PhilosophicalSociety in Philadelphia. Historians should regard as provisional anyinterpretations of Wright put forward by those like myself whohave yet to get themselves there. Finally, a suggestion to anyonewho does get the opportunity to explore those papers: the 1932paper with its captivating (and, according to Wright’s harshest crit-ics, deeply superficial, muddled and misleading) adaptive land-scapes—recently a whole issue of Biology and Philosophy wasdevoted to them (vol 23, number 5, November 2008)—is surelynot the best published textual preparation for that exploration. Abetter preparation is to ask why Wright formulated his generalevolution question about irreversible changes in species heredities

exactly as he did, why he took up those three main challenges ta-ken up in his answering that question: the whopping, choppingand stopping challenges, those three challenges that dominate in1931, and why some dozen terms are associated with almost allhis leading idées fixes, above all with his SBT in 1931 if not alwaysthereafter—balance, heterogeneity and homogeneity, moving equi-librium, plasticity, cumulativity, irreversibility, intelligibility, lev-els, organisation and so on.

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Cain, J. (2009). Rethinking the Synthesis Period in Evolutionary Studies. Journal ofthe History of Biology(42), 621–648.

Delisle, R. (2009). Les Philosophies du Néo-Darwinisme. Paris: Presses Universitairesde France.

Depew, D., & Weber, B. (1995). Darwinism evolving: Systems dynamics and thegenealogy of natural selection. Cambridge, Mass: MIT Press.

Gayon, J. (1998). Darwinism’s struggle for survival: Heredity and the hypothesis ofnatural selection. Cambridge: Cambridge University Press.

Hodge, C. (1874). What is Darwinism? New York: Scribner and Armstrong.Hodge, J. (1992). Biology and philosophy (including ideology): A study of Fisher and

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