Teleology and reduction in biology

Teleology and Reduction in Biology

JONATHAN JACOBS

Philosophy Dept.State University of New YorkPlattsburgh, NYI12901, U.S.A.

ABSTRACT: The main claim in this paper is that because organisms have teleologicalconstitutions, the reduction of biology to physical science is not possible. It is argued thatthe teleology of organisms is intrinsic and not merely projected onto them. Many organicphenomena are end-oriented and reference to ends is necessary for explaining them.Accounts in terms of functions or goals are appropriate to organic parts and processes.This is because ends as systemic requirements for survival and health have explanatorysignificance with respect to the processes that contribute to and constitute them. Reduc-tionism cannot accommodate this sort of higher-level to lower-level explanation and socannot account for why lower-level phenomena are as they are. Reductionism, it isclaimed, is ultimately descriptive and not explanatory because it cannot regard teleologicalrequirements as themselves basic. In seeking to explain them away it forfeits explanatorypower.

KEY WORDS: Teleology, reduction, hierarchy, intrinsic end.

INTRODUCTION

Reductionism as a strategy of scientific explanation is motivated by boththe desire for and the promise of a unified science that economizes ontypes of entities and laws. The desire is widely shared and the promisewidely regarded as fulfillable. As a strategy, reductionism is admirable.Unity and economy are hard to object to, and the search for underlyingmechanisms and fundamental entities that account for grosser phenomenais a central task of producing the scientific picture of the world. But theappeal of the promise should not blind us to circumstances that canundermine it. I will argue here that there are objective teleologicalcircumstances, involving functionality and end-directedness, for example,that block reduction of biology to the physical sciences. The overallsystemic good of an organism is a property of it which has a central placein explaining the parts and processes that constitute an organism, at a timeand over time.'

Before presenting this case I should say something about just what Imean by teleology. The issue is a very old one, traceable to antiquity.It is a commonplace that Aristotle's natural philosophy is somehowpre-scientific and obsolete for being teleological. And a familiar note of

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praise heard about early modern science is that it eliminated teleologyfrom vast portions of theorizing about natural phenomena. But teleologyhas proved remarkably adaptable. It is a notion that persists in biology. Itis not a crystal clear, rigorously defined notion but its most familiarassociations are goal-directedness, functionality, purposiveness, preferredstates and a few other concepts, all at least loosely having something to dowith attaining and/or maintaining ends. That is, the common partialmeaning of these notions is that if a process or system is teleological, it isoriented or structured and operates with reference to some end, which isexplanatorily important, even if not temporally final.

Phenomena regarded as teleological are much more familiar and readilyrecognized than the notion itself is clear. The intentional behavior ofhuman agents is teleological. Biological phenomena such as homeostasis,immunological response, or lactation are teleological. The operations ofartifacts, such as the arm on a record turntable or a fuel-distributionsystem in an aircraft, are teleological. In each case, part of the explanationof what is occurring refers to the state or condition brought about.Aristotle called this the "that-toward-which." We tend to call it the goal,function or purpose.

While intentional, organic and artifact teleologies are all related throughthis notion of end-orientation, there are important differences betweenthem. The teleology of intentional agents involves purposes in the mental-istic sense, the conception of a goal or end. Neither organic nor artifactteleology involves this. And it was the assimilation or at least analogy toconscious purposiveness that made teleology in natural science seem soout of place and obscurantist. Artifacts are not naturally occurring entities.They are designed and made, and what they are for and how well theyfunction is explained with reference to an external agent's purposes. Theteleology of artifacts is in this sense not intrinsic. The teleology oforganisms, as I shall argue, is intrinsic; though it does not involve mental-istic entities or conscious purposes.

Organic teleology has proved especially difficult and controversialbecause it seems to occupy this intermediate position between being anagent and being an artifact. The problem is not so much in recognizingwhat phenomena are teleological, but in supplying an analysis of just whatit is that makes them so. Analogies to intentionality are not scientificallyhelpful. Analogies to thermostats and other purely physical artifacts andsystems leave out the intrinsic character of organic teleology.

The analysis of teleology has been undertaken along a number of lines,including negative feedback processes, preferred state systems, informa-tional programs, directive organization and other interpretations. 2 None ofthese has clearly prevailed. They are attempts to explicate how systems orprocesses persist in either bringing about certain states within a restrictedrange of variability, or a series of such states in a specific temporal

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order (as in embryological development, for example). The systems andprocesses exhibit self-regulation and adaptation to overall systemic andenvironmental change. It is these sorts of internally-regulated, adaptableprocesses that achieve and maintain certain states to which teleologicalnotions apply in a way that strictly mechanico-causal accounts are inade-quate to. Thus, teleology is an important character in the story of whetheror not biological science is reducible.

It is not my purpose here to try to solve the problem of teleology or topresent a logic or semantic for teleological accounts. Rather, I will indicatethe general features of the teleological character of organisms and whythese features are neither eliminable nor reducible to non-teleologicalphenomena.

I. WHAT IS THE PURPOSE OF TELEOLOGY?

Advocates of the reduction of biological science to physio-chemicalscience often make two allowances to the peculiarity of biological phe-nomena. One is that it makes sense to study them as parts of wholes orsystems rather than individually. The second is that teleological languageand concepts are useful in formulating questions and getting answers. Buta completed reductionist program would terminate both allowances. Nospecial organizational principles that could not be rendered in the terms ofthe reducing theory would appear in it. No teleological language differentin sense or cognitive content from non-teleological language would figurein it. This is not a result that can be legislated a priori. But advocates ofthe reductionist program, such as Nagel and Schaffner for example, haveargued that there are no decisive reasons to think it cannot succeed. Theobstacles are many and difficult, but empirical.

Claims like these, which appear perfectly reasonable, make any anti-reductionist argument sound like a delaying action by a side which won'tadmit inevitable defeat. I will argue here that organisms are systems whichare intrinsically teleologically organized and that this fact is a permanentobstacle to reduction. This is not to say that organisms are made of anyspecial matter or that biological phenomena cannot be fruitfuly studied inphysio-chemical terms. But even a completely physio-chemical account of(at least some) biological phenomena will not be a complete account. Theclaim I will explicate is that because of the teleological organization oforganisms there is an explanatory relation that goes from the level oforganization of the entire entity as a system to the subsystems and partsand processes that constitute the entity. There is an intimate relationbetween the character of organisms as complex, developing wholes andtheir being teleologically organized. An organism involves a hierarchy ofmaterial components and sub-systems, from the molecular level through

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the cellular and physiological levels to the level of the persisting individualof a particular species. Most scientific explanation goes in a direction fromlower to higher levels in the sense that underlying mechanisms and theirmaterial components are explanatory with reference to grosser character-istics. My claim here is that this preferred direction of explanation isreversed in the biological context. Hierarchical organization is explanatorywith respect to (at least some of) its components and not merely con-sequent upon them.

I am concerned with the question of whether, for example, teleologicalfacts at the level of cell division explain facts about nuclear mitoticprocesses. It is because higher level teleologies explain lower levelphenomena that reduction is thwarted.

A recurrent objection to teleological accounts is that they are notexplanatory. This claim is based on the notion that their idiom involvesreference either to future states, or purposiveness and both of theseoffend against the metaphysic and semantics of scientific method. Ifgoal-directedness or function-ascription are scientifically acceptable, this isbecause their distinctively teleological dimension can be stripped awayand translated into or replaced by mechanistic substitutes. But the errorof this position lies in its miscontrual of teleology. Teleology manifests,as I remarked above, in (at 'least) three varieties. The teleology of self-determining agents involves mentalistic entities and conscious purposes.But this is not organic teleology. The teleology of artifacts is conferredupon them. They are teleological entities in a manner dependent uponintentional agents. Organic teleology is real but does not involve consciouspurpose. It is intrinsic and not merely conferred. But it should not bedenied on the basis of a misleading comparison to intentionality. Teleo-logical accounts, explanations in terms of goals or functions apply toorganisms because they are organized and develop in a distinctivelyteleological way. By this I mean that what it is to be an organism is for theentity to undergo a multi-stage, internally-regulated history of develop-ment. Development is not mere alteration or change. It is an end-orientedprocess. But biological development and ends can be empirically specified.They are not immaterial processes. But neither are they material processesthat can be accounted for exhaustively in non-teleological terms. Organi-zation and interaction of parts and processes at a time as well as over timerequire a teleological account because they are teleological phenomena.

The idea of teleology is normative and perhaps this is the mostunacceptable aspect of it to reductionism. But it is normative in a mannerwhich is altogether amenable to empirical and nomological specification.The good of an organism or the well-functioning of a part of it can beobjectively explicated with reference to what we know to be its require-ments for survival health and growth, for example. What counts assurvival, health or successful growth for an organism is not a reflection of

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our decisions about it. It is intrinsic to the entity, because of the distinctivetypes of careers of development organisms undergo. I join with Woodfieldin defending "the view that a biological end of an organism is essentially astate or activity that is intrinsically good for the organism" (Woodfield1976). I also hold with him that "the crucial feature of organic functions isthat they do the organism good".... "S's bodily functions do S good bypromoting S's natural ends, where 'ends' means states or processes oractivities that are intrinsically good for S" (Woodfield 1976).

Because organisms have intrinsic goods, and their development is end-oriented, parts and processes are properly accounted for teleologically.Such accounts are genuinely explanatory because they render intelligiblethe plasticity, persistence, integration and alteration of biological processesand parts. While reductionism excludes teleology because it is notexplanatory, my claim is that reductionism is frustrated because it leavesteleological phenomena unexplained. How does the reductionist caseproceed?3

II. THE REDUCTIONIST STRATEGY

A typical reduction would involve showing how statements about genesfor example, have counterparts which are statements about molecules; andhow statements about processes like recessive epistasis or characteristicsat the phenotypic level can be completely characterized and explicatedchemically. The counterpart statements must satisfy certain conditions thathave been variously formulated in order to count as satisfying the relationof reduction. We need not be concerned here with the intricacies ofdefinability and reduction functions. We can assume that a satisfactorygeneral formula for reduction is available. The principle of reduction, asstated by Schaffner, is as follows:

... given an organism composed out of chemical constituents, the present behavior ofthat organism is a function of the constituents as they are characterizable in solationplus the topological causal interstructure of the chemical constituents. (The environ-ment must of course in certain conditions be specified.) (Schaffner 1976)

He goes on to add that this does not entail "that living organisms can onlybe fruitfully studied as chemical systems" (Schaffner 1976).

As I remarked, it is surely possible to give physio-chemical accounts ofbiological phenomena. But a negative answer to the question whether theyare complete accounts motivates my argument against reductionism. Whyshould we think such accounts are somehow incomplete?

Some stage-setting is necessary to answer this question. First, while it iswidely believed that an organism's properties and history are governed (ifnot determined) by a genetic program, this is a simplification that falsifies.

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The role of nucleic acids is justifiably celebrated but the road from DNAto RNA to protein to cell to tissue to organism is exquisitely complex.Nucleic acids initiate and control a good deal of the traffic but they areonly part of the story. Protein synthesis, cell division and differentiationand organic maintenance and development involve a manifold andheterogeneous hierarchy of components and processes not all of whichare controlled by genetic material. An account of say, endosteum orepithelium may refer to specific segments of genetic material and theproducts of their molecular activity through a long interlocking chain ofreactions. But this does not explain why cells of certain types replicate injust the way they do at just the places they do in the overall system.Similarly for the physiology of embryological development. This is aprocess of which all parts are composed of materials familiar to chemistry.But the meticulously ordered development of a hierarchy of interactingsubsystems is not itself a process accounted for in terms of the lawsgoverning the chemical constituents. We might distinguish between "con-stitutive" reduction and "dynamic" reduction; the former referring toreduction to certain types of materials, the latter to the articulation ofstructure and function reduced to a lower level theory. It is the secondtype of reduction that I believe cannot go through. Explaining the "why" ofdifferentiation, development and maintenance requires that our explana-tions go from "top" to "bottom."

"Top" and "bottom" here are not simply epithets for macro and micro.The latter terms are appropriate for purely aggregative entities. Theformer pair of terms has a different sense, appropriate to hierarchicalproperties.

Hull states that:

If one examines actual physical theories, and not the usual textbook examples, onediscovers that the differences between biological and purely physical phenomena do notlook so great. Biologists do not have a corner on organization. Graphite and diamondare extremely different gross substances. Yet they are both made out of one and thesame element - carbon - and nothing else. All their gross differences stem solely fromdifferences in the organization of their constituent molecules. (Hull 1974)

Biologists do not have a corner on organization. But they do have acorner on naturally occurring teleological organization. The fact that thereis a complete physio-chemical characterization of say, bone marrow, livercells or neurons does not exclude or eliminate a teleological explanation oftheir coming to be and behavior. Nagel, for example, has tried to dis-charge teleology in favor of a non-teleological characterization of directiveorganization compatible with the mechanico-reductionist program. But theformulation he gives of the relations between independent state variablesis, in essence, descriptive not explanatory. It would report how a certaincausal substructure in a system operates. But it does not explain why that

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substructure operates as it does when in that type of system. His formulafor goal-directedness can be a basis for generating laws. But my point isthat these laws are not adequately explanatory.4

The reason for this is that the complete explanation of the behavior of asubsystem involves reference to the wider corporate system of which it is acomponent. This point can be misinterpreted. I do not mean the widersystem just in the sense of the physio-chemical make-up of the entireorganism. That would be compatible with reductionism. I mean widercorporate system in the sense of the overall hierarchical structure of theentity, its different, heterogeneous levels. Why insist on this?

Consider growth.

Organic growth is not a process of accretion, nor does it build upon an enduring frame.The molecular fabric of the body enjoys no substantive permanence whatsoever....(Medawar 1981)

Most growth is articulation, elaboration and integration. One of the crucialphenomena of growth is differential activities of genetic material in theproduction of behaviorally differentiated cells, tissues and organs and soon. Some have fixed locations, like liver cells; some move around thesystem, like leucocytes. One kind of differentiation is that whereinimmunological capabilities develop at different times. Immunologicaltolerance and rejection are not realized all at once. The dynamic of thispattern of development is fully explicable only with reference to thecomplete system in which it occurs. There are higher level constraintson lower level activity. Each level of description and explanation isconstrained by the next higher level, the last of which is the overallteleological form of the developed system.

My point is not just that because organisms are complex systems ofinterrelated parts amenable to different levels of description we can adoptcertain attitudes toward them. I am arguing that there is a real teleology tothe system as a whole, both synchronically and diachronically - that isexplanatory with reference to the various levels and activities that con-tribute to it.

There is a tendency to identify minuteness with fundamentality ofexplanatoriness. But at least in the biological context, this is just not thecase. The activities of constituents are at least sometimes determined bythe wholes (at various levels) to which they belong. Consider stimulusreceptivity. There are various types of receptor specificity, mechanical,photic, chemical and mixed types, with different thresholds of stimulusadequacy. For many receptors steady stimulation will result in decliningexcitability. This is called adaptation.

The tactile stimulation of clothing quickly ceases to be noticed after dressing; a delicateodor is detected only briefly in spite of repeated attempts to recapture the experience... The slowly adapting receptor is equally important biologically for it continuously

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monitors where a failure of input information would lead to disastrous results. Thebalance in groups of contracting muscles must be constantly regulated if equilibrium isto be maintained; if tension receptors adapted quickly, they would be quite useless.Different receptors are nicely specialized to meet these varied demands. (Hoar 1975)

Consider a second case. Depending upon whether an animal is acontinuous feeder or a periodic feeder the activities involved in digestionand absorption must be coordinated and regulated in different ways.

The continuous feeder thus avoids the problems of storage between meals and thepotential hazards of fluctuations in the blood levels of digested foods. A periodicfeeder, however, may obtain large volumes of food during a relatively brief period, andthese must be digested, absorbed and stored to avoid excess flooding of the tissues withnutrients. At the upper level of phylogeny, a complex interaction of the autonomicnervous system and endocrmines initiates enzyme secretion, regulates the discharge ofaccumulated juices and governs the motility of the gut and the passage of food throughit. (Hoar 1975)

The two cases are chosen to illustrate the multi-level complexity ofregulated, coordinated biotic function. The complexity itself is no argu-ment against reduction. The processes described can surely be spelled outin physio-chemical terms. But the physio-chemical regularities do notaccount for the fact that certain processes are systemic requirements orexactly how they should occur. These regularities instantiate those re-quirements and many of the control mechanisms are molecular. Yet areductionist account of stimulus receptivity or digestion or innumerableother biological behaviors explicates the compositional substructure with-out expressing why those behaviors are as they are in systems of the typesthey are in.

III. THE EXPLANATORY ROLE OF TELEOLOGY

As an analogy consider how the rules and procedures of an institutionsuch as the U.S. Senate define constraints on and requirements of thecommittees and individuals it comprises. The rules and proceduresconstrain and explain the behavior of those they apply to at a time andover time; where certain bills can originate, how appointments areapproved, what counts as censure, passage of a resolution or a law and soon. Once an individual is "taken up" into the system, though he may act onhis own initiative and direct his own behavior, what counts as Senatorialbehavior is defined by a system he is part of but not exhaustivelyaccounted for in terms of the totality of his behavior and that of all theother individual senators. The organizational and dynamic principlescriterially account for well-ordered and disordered behavior. And analo-gously to organisms, the behavior of the Senate is plastic, persistent andeven irritable.

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The Senate case is only an analogy, not a model. But it does indicate byanalogy the logical character of top to bottom explanation, wherein formaland structural constraints of an overall system taken over time determineat any time significant activities of its components. This is not backwardcausation. The product of a process does not determine it. The overallsystemic condition of being a member of a certain species determines atany time the permissible ranges of state variables for the subsystems andprocesses that constitute the entity. Some of these ranges are homeostaticand some homeorhetic. Vital activities are never simply at one level, asjust between cells or between tissues or between macromolecules. Theyare always vertically integrated throughout levels of the organizationalhierarchy. Photosynthetic reactions may involve mechanical change in theplant's bending toward the source of radiant energy, genetic activity in theregulation of the process, chemical change in the energy conversionprocess and the electron exchange involved in the series of reactions.

My strategy has been to note how while the reductionist programallows us to say what happens at a privileged level of analysis it cannotcapture and express (at least some of) why it should be happening thatway. To account for that we must know the character of the overall systemas an enduring entity with a kind-specific integrity. At this point it willbe objected that the species-specific systemic requirements are merelyphysical boundary conditions that can be reductively accommodated byreduction functions and correspondence rules. As Nagel puts it:

Accordingly, a necessary requirement for the mechanistic explanation of the unifiedbehavior of organisms is that boundary and initial conditions bearing on the actualrelations of parts of hving organisms be stated m physico-chemical terms. (Nagel 1970)

This is unexceptionable as a fact about how reductionism would have toproceed. But it does not, by virtue of its correctness, indicate that suchreduction could be carried out. My claim is that the boundary conditionsand systemic requirements are not just more of what must be reduced.Consider the Senate analogy again. The Senators (among others) formu-late, enact and implement the rules and procedures that criterially governtheir actions. But those are not reducible to the behavior of Senators at atime or over time. Moreover, there is no relation of antecedence andconsequence obtaining between the application of the formulae and thebehavior. They are coeval, though the former are essential to explainingthe latter. In the characteristic species-specific activities that constitute anorganism there is an analogous explanatory relation between relativelyhigher and relatively lower levels. Constituents and their arrangements donot exist prior to and as antecedent causes of the systems they figure in.All of this is simultaneous. Adequate explanation of the lower levelactivities and arrangements counting as constitutive of the organisminvolves reference to the overall systemic requirements of the entity at that

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stage in its career. And these requirements are distinctively teleological. How the entity must be to persist and develop is explanatorily prior to what happens in order to bring it into that condition. This yields an altered picture of the relation of levels in the descriptive/explanatory hierarchy. The hgher levels are not connected to the lower levels by rules of synthetic identity or derivation. Instead they express constraints that are explanatory with respect to lower levels. The explanations are teleological because the lower level activities satisfy systemic requirements determined by the higher level constraints. They are the that-toward-which the lower level activities are directed. This is so in a dual sense, both synchronically and diachronically. The first is that at any given time in order to be the kind of thing the entity is it must satisfy a hierarchical set of conditions. For example, an organ in a certain kind of animal must meet molecular, cellular, histological and mechanical requirements. In any interval there is a class of compositional, structural and behavioral conditions it must meet. Also, across a series of intervals it must meet a temporally ordered class of changing conditions of those types.

To regard this temporarily-extended teleological hierarchy as a method- ological device without a real correlate is to opt not to expand the explanatory program to regard the facts of systematization as themselves basic. It would see them as derivative and consequent upon facts about components of the systems.

My claim is that facts of systematization are explanatorily significant in their own right. They are essential to accounting for the regularities and their coordination that obtain at lower levels. This is so because they impose teleological determinants that order those regularities.

NOTES

' 1 owe a debt of thanks to James Anderson of the University of Pennsylvania and Simon Saunders of Oxford Univers~ty for thelr helpful criticisms and remarks. Also, anonymous referees for this journal. and the Edltor, Michael Ruse, made a number of valuable suggestions and insistences. None of these indwiduals is responsible for any unclarities or errors that remain in the paper.

See chapter 4 of D. Hull's Phzlosophy of Biological Science for a d~scuss~on of various interpretations of teleology and a good synopsis of the merits and defects of the different analyses. ' I should make it clear that I am concerned here only with the teleology involved in an organism's history, not w~th the teleology of populations or the evolutionary process.

See E. Nagel's 'Teleology Revisited', m Journal of Philosophy, pp. 261-301, May 1977. In that plece Nagel explicates and evaluates a number of important treatments of teleolog~cal explanation. Towards the close, he states that "goal-ascriptions can be explicated without employing any teleological notlons . . ." and that "functional statements, as well as the presuppositions of functional ascriptions, can also be rendered without using functional concepts, . . ." (p. 229). These results are taken to have the effect of removing obstacles to reduction. If I am right, teleological accounts are, in fact, explanatorily necessary.

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REFERENCES

Hoar, W. S.: 1975, General and Comparatlve Physiology, Prentice-Hall, Englewood Cliffs,NJ. Ch. 3, Ch. 16.

Hull, D.: 1974, Philosophy of Biological Science, Prentice-Hall. Englewood Cliffs, NJ, Ch.5.

Medawar, P. B.: 1981, The Uniqueness of the Individual, Dover Publications, Inc., NewYork, p. 88.

Nagel, E.: 1970, 'Teleological Explanations and Teleological Systems', m B. Brody (ed.),Readings in the Philosophy of Science, Prentice-Hall, Englewood Cliffs, NJ, pp. 106-120.

Nagel, E.: 1977, 'Teleology Revisited', Journal of Philosophy 74, No. 5.Ruse, M.: 1973, Philosophy of Biology, Hutchinson's University Library, London.Schaffner, K.: 1976, 'The Watson-Crick Model and Reductionism', M. Grene and E.

Mendelsohn (eds.), Topics in the Philosophy of Biology, D. Reidel, Dordrecht, p. 121.Woodfield, A.: 1976, Teleology, Cambridge University Press, Cambridge, Eng., p. 111, p.

130.

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Teleology and reduction in biology