2 For a philosophical response to ‘the new messiness,’ see for example John Dupre’s provocative new book, The Disorder of Things (Cambridge, MA: Harvard University Press 1993). But while Dupre and I both urge major surgery on our ontologies, methodologies, and epistemological assumptions, and make movements in many of the same directions, I believe that my surgery is ultimately more conservative, particularly in defending a liberalized (and non-eliminative) descendant of classical mechanistic materialism, and is also more in accord with actual scientific practice. (Our differences on the former but I think not on the latter point may be in part ideological or rhetorical rather than substantive.) Dupre could urge in return that I haven’t paid sufficient attention to the social determinants and aspects of our practice. To this I plead guilty, though I think the view argued here can both deal with and in part explain those complexities.

3 See Levins, R. “The Strategy of Model Building in Population Biology,’ American Scientist (1966) 421-31Google Scholar, reprinted in E. Sober, ed., Conceptual Issues in Evolutionary Biology (Cambridge, MA: MIT Press 1984); see Wimsatt, W. ‘Robustness, Reliability, and Overdetermination,’ in Brewer, R. and Collins, B. eds., Scientific Inquiry and the Social Sciences (San Francisco: Jossey-Bass 1981)Google Scholar for an extensive analysis and review of the concept and methodology; and for relevant case studies, see Wimsatt, W. ‘Randomness and Perceived Randomness in Evolutionary Biology,’ Synthèse 43 (1980) 287-329CrossRefGoogle Scholar and ‘Reductionistic Research Strategies and Their Biases in the Units of Selection Controversy,’ reprinted in Sober, Conceptual Issues. See also Campbell, D.T. ‘Pattern Matching as an Essential in Distal Knowing,’ in Hammond, K.R. ed., The Psychology ofEgon Brunswik (New York: Holt, Rinehart, and Winston 1966)Google Scholar. Campbell’s concept of ‘triangulation’ captures most of the ideas central to the notion of robustness; his work with Don Fiske on the ‘multitrait-multimethod matrix’ brought this methodology to the social sciences. See Campbell, D.T. and Fiske, D.W. ‘Convergent and Discriminant Validation by the Multitrait-Multimethod Matrix,’ Psychological Bulletin 56 (1959) 81-105CrossRefGoogle ScholarPubMed.

4 Hacking, I.Representing and Intervening (Cambridge: Cambridge University Press 1983)CrossRefGoogle Scholar

5 See my ‘Robustness, Reliability, and Overdetermination,’ for the fullest treatment, but also my ‘Complexity and Organization,’ in Schaffner, K. and Cohen, R.S. eds., PSA 1972, Boston Studies in the Philosophy of Science 20 (1974) 67-86Google Scholar; and ‘Reductionism, Levels of Organization, and the Mind-Body Problem,’ in Globus, G.G.Maxwell, G. and Savodnik, I. eds., Consciousness and the Brain (New York: Plenum 1976), 199-267CrossRefGoogle Scholar.

6 Simple mathematical models of this and other related reliability calculations are worked out in my ‘Robustness, Reliability, and Overdetermination.’ If the probabilities of being correct, or of introducing error through an inference are both bounded between zero and one, then serial dependencies always reduce reliability and parallel redundancies always increase it.

7 The apparent robustness of the ‘result’ that group selection could not be causally efficacious is one such case, where the various supposedly independent considerations supporting this conclusion turned out not to be after all. Similarly, the once highly touted ‘validity’ of IQ scales is seriously compromised by the fact that agreement with older tests was used as a criterion for the inclusion of questions in newer tests, so the tests — even as composed with entirely different questions failed to be causally or probabilistically independent in the relevant sense. See my ‘Reductionistic Research Strategies’ and ‘Robustness, Reliability, and Overdetermination.’

8 N. Rasmussen, ‘Facts, Artifacts, and Mesosomes: Practising Epistemology with the Electron Microscope,’ Studies in History and Philosophy of Science 24

9 Sylvia Culp, ‘Defending Robustness: The Bacterial Mesosome as a Test Case’ (unpublished ms)

10 See further discussion below, and see my ‘Reductionistic Research Strategies’ and ‘Robustness, Reliability, and Overdetermination’ for discussions of cases of spurious or pseudo-robustness in population biology and psychology; also see S. Culp, ‘Objectivity in Experimental Inquiry: Breaking the Data-Technique Circle’ (unpublished ms) for a careful and enlightening dissection of degrees of independence and interdependence among experimental techniques in molecular genetics, and contrary arguments by Rasmussen (‘Facts, Artifacts, and Mesosomes’) and Culp (‘Defending Robustness’) about the use of robustness in the analysis of an artifactual ‘entity,’ the mesosome, in recent cell biology.

11 See Campbell,’Pattern Matching.’

12 Thus, in fascinating work in the late 1960s, on the interactions of visual and tactile modalities, Rock, I. and Harris, C.S. ‘Vision and Touch,’ Scientific American 216 (1967) 96-104CrossRefGoogle ScholarPubMed, found a complex conditional dependency in which sense we trusted when both were used. When no disparity in judgment between the two was noticed, vision was taken over touch — a judgment justified evolutionarily by the fact that we can make higher-resolution and more accurate discriminations (for shape, pattern, texture, and the like) with vision than with any of the other spatial modalities. When a disparity between the judgment of the senses is noticed, however, touch is taken over vision — again a reflection of the fact that vision is more subject to systematic distortion than touch (witness the ‘bent stick’ illusion). The accuracy and reliability of our different scientific instruments are related and interdigitated in ways which are at least as complex as this case, and we have to learn which to trust, under what conditions, and why.

13 A serious obstacle to both activities occurs if we cannot discover how the means of access (our instruments) work and how they can be biased or break down. In a review of work in the thirty years since the appearance of their classic and widely cited paper recommending a variant of this methodology in the social sciences, Donald Fiske and Donald Campbell conclude that its limited success there is due to the much greater complexity of processes affecting measurement in the human sciences, and the lack of an adequate ‘theory of the instru-ment.’(Fiske, D.M. ‘Citations do not Solve Problems,’ Psychological Bulletin 122 [1992] 393-5.CrossRefGoogle Scholar) A key part of the ‘theory of the instrument’ (such things as questionnaires, interviews, participant observation, and the like) must be how it interacts with the object, and this is crucial to telling whether a result is a property or product of the object, the instrument, the testing situation, or some complex relation among some or all of the above.

14 W. Wimsatt, ‘Golden Generalities and Co-opted Anomalies: Haldane vs. Muller and the Drosophila Group on the Theory and Practice of Linkage Mapping,’ in Sarker, S. ed., Fisher, Haldane, Muller, and Wright: Founders of the Modern Mathematical Theory of Evolution (Dordrecht: Martinus-Nijhoff 1992), 107-66Google Scholar

15 As Sergio Martinez points out in ‘Robustness and Objectivity’ (draft in English; Spanish version in Dianoia [1992]), it was also often argued that primary qualities were aggregative, which would further increase the tendency to locate the ‘real’ properties at the lowest level of aggregation—a close cousin to foundationalism. Martinez points to interesting historical connections between ideas of realism, robustness, and aggregativity. See Wimsatt, W. ‘Forms of Aggregativity,’ in Donagan, A.Perovich, N. and Wedin, M. eds., Human Nature and Natural Knowledge (Dordrecht: Reidel 1986), 259-93CrossRefGoogle Scholar and ‘Emergence as non-Aggregativity,’ in P.J. Taylor and j. Haila, eds., Natural Contradictions: Perspectives on Ecology and Change (forthcoming) for further discussion of aggregativity.

16 We will see examples of this below in the level-relativity of explanation, illustrated using the example of Brownian motion: between-level phenomena are always referred up or down in level for explanation.

17 I do not think this results in the demise of deductive arguments, or of philosophy, or in the fusion of philosophy and science, though there are clearly some activities which could be viewed as either or both. It does suggest a broader critique of philosophical methodologies which urge formulation of each argument in deductive form, come what may, and heaps scorn on other styles of argument, without concern for what is the appropriate argument for the context. A valid but unsound argument, or even an argument which is both valid and sound, but whose conditions of soundness are extremely restrictive, may sometimes wisely be replaced by a broader but less fragile argument, or by a number of mutually supporting though individually weaker arguments. We are similarly sometimes ill-served by the search for exceptionless laws. In both of these, we have been misled by our concerns with logic. This is not to deny that there are contexts for which deductive arguments are the tool of choice —but only to deny that they have a priority or preferability over all other tools in all contexts, or have a particular foundational significance. Robustness also gives qualitatively plausible ways of dealing with structures which contain contradictions and approximations — two features which are difficult to handle naturally with deductivist tools.

18 See Wimsatt, ‘Heuristics and the Study of Human Behavior,’ in Fiske, D.W. and Shweder, R. eds., Metatheory in Social Science: Pluralisms and Subjectivités (Chicago: University of Chicago Press 1985), 293-314Google Scholar; and ‘Golden Generalities and Co-opted Anomalies.’

19 See Wimsatt, ‘Reductionism, Levels of Organization, and the Mind-Body Problem’; and ‘Reductive Explanation: A Functional Account,’ PSA 1974 (Dordrecht: Reidel 1976), reprinted in Sober, Conceptual Issues.

20 McClamrock, Ron ‘Marr’s Three Levels: A Re-Evaluation,’ Minds and Machines 1 (1991) 185-96CrossRefGoogle Scholar; D. Marr, Vision (Cambridge, MA: MIT Press 1982)

21 For those for whom this matters, I have deliberately picked cases where the replicator is also an interactor.

22 They are represented in a compositional manner — and may be compositionally related to other mentalistic entities. This does not imply, however, that they or any mental objects would map to physical objects (as opposed to physical configurations, stable dynamical patterns, or whatever) in a successful material theory of the mind — any more than we would expect the objects of ‘object-oriented programming’ to do so. In fact, there is reason (suggested in part by examples like this) to believe that they wouldn’t. See my ‘Reductionism, Levels of Organization, and the Mind-Body Problem,’ part III, for further discussion.

23 Levels are probably most frequently discussed in conjunction with accounts of hierarchical organization, of which there is an enormous literature, much of it suggestive and useful for present purposes. While many of the systems with multiple levels are hierarchical in character, I don’t wish to couple levels talk to hierarchies, since I will also be interested in situations where the conditions required to define hierarchies are violated. For more on hierarchical organization, see Partee, H.H.Hierarchy Theory: The Challenge of Complex Systems (New York: Braziller 1973)Google Scholar, and for a more recent work which draws particularly broadly on the literature, see Salthe, StanleyEvolving Hierarchial Systems: Their Structure and Representation (New York: Columbia University Press 1985)CrossRefGoogle Scholar.

24 I would urge, however, that it is reductionistic, or at least broadly mechanistic, as those terms would be understood by most scientists. See Wimsatt, ‘Reductive Explanation,’ or ‘Reduction and Reductionism,’ in Kyberg and Asquith, eds., Current Problems in Philosophy of Science (East Lansing, Ml: Philosophy of Science Association 1979), 251-77.

25 There is a significant epistemological parallel here with the research program of Kauffman’s, StuartThe Origins of Order: Self-Organization and Selection in Evolution (Oxford: Oxford University Press 1993)Google Scholar, where Kauffman seeks to argue that many adaptive ‘emergent’ properties of systems emerge relatively directly as ensemble properties of classes of systems. Since they are in effect high entropy properties of such systems, we get them ‘from the physics’ for free, and we don’t have to invoke special selective processes at higher levels to explain them. Indeed, Kauffman’s research program turns out to be a particularly revealing special case of this which merits substantial further study for its methodological lessons.

26 Simon, H.A. ‘The Architecture of Complexity,’ reprinted in his The Sciences of the Artificial (Cambridge, MA: MIT Press 1981)Google Scholar

27 Philosophical constructs like Wilfred Sellars’s ‘manifest image’ beg to be analyzed in terms of levels of organization, though the mixture of psychological and physical properties in Sellars’s construct render the analysis not straightforward, and unlike the ‘folk psychology’ which some writers have derived from Sellars’s ‘manifest image,’ levels are not eliminable through conceptual revolutions. (Of course, ‘folk psychology’ may not be either!) See Sellars, WilfredPhilosophy and the Scientific Image of Man (London: Routledge 1963)Google Scholar.

28 To go up a level, a lower-level process must in effect be a deviation-amplifying process (at least under those conditions) and more generally if it is an adaptation, it must presumably be such under a suitably broad range of conditions. This suggests that a fuller exposition of this condition may require reference to the concepts of canalization and of deterministic chaos. One important way (and perhaps the only systematic way) for an event to have effects which go down in level, is through a selection process.

29 The fortuitous term ‘level leakage’ I owe to my former student Stuart Glennan, whose inventive and highly original work on causation and mechanism provides important further explication of both notions which support the central role that a mechanistic perspective plays in this account. See his ‘Mechanisms, Models, and Causation’ (PhD diss., University of Chicago 1992).

The ways in which we exploit ‘level leakage’ to gain access to other levels became much clearer to me through my involvement in 1979-81 (as part of a users’ group) in helping to program a custom ROM module for the Hewlett-Packard HP-41C programmable calculator. The calculator was designed to be programmed in RPN (for ‘Reverse Polish Notation’), a sort of assembly-level language which allowed direct manipulation of program instructions, numbers, and alphabetical characters in a controlled region of the calculator’s memory, and prevented access to other regions of memory used by the calculators ‘system software,’ on the other side of a ‘curtain.’ A ‘bug’ in the definition of some of the keyboard functions on some of the early calculators gave unintended ways of creating new ‘synthetic instructions’ which gave ways of moving the ‘curtain’ and of directly manipulating the contents of control registers behind the curtain on all HP-41 calculators, whether they had that bug or not. This led to a new machine-specific discipline, called ‘synthetic programming,’ which gave the synthetic programmer control over many things on the HP-41 that Hewlett-Packard engineers never intended (e.g., control over individual elements in the LCD display, and individual pixels in the printer output, and the ability to do all sorts of bit manipulations to compose new kinds of instructions). ‘Synthetic programming’ thus gave new capabilities, and sometimes striking increases in efficiency, speed, or power. On the down side, it also gave new and dangerous ways of ‘crashing’ the calculator, and exploiting this new resource required much greater knowledge of the details of the machine, such as the Hexadecimal code for all machine instructions, and greater knowledge of how they worked, and how they interacted with the hardware. See the 500+ page PPC ROM Users’ Manual (The Personal Programmable Calculator Users’ Group, Affiliated with Hewlett Packard 1981) for the section on the history and description of ‘Synthetic Programming,’ and also a later (1982) book of that same title by its main developer, William Wickes.

30 Identity theories are now out of fashion. Token identities seem too weak since they seem to claim nothing more than spatio-temporal coincidence, and say nothing about how the upper level phenomena are explained by the lower level characterization. And type identities seem to be subject to a myriad of possible counterexamples — both of the ordinary garden variety derived by considering how two different people with two different and presumably differently wired brains can think the same thought, and also of the more Procrustean variety preferred by philosophers — stimulated by images of the mental life of the population of China or a cerebral Martian plant, both of which are supposed to have the same functional architecture as you or I. (I find the first kind of case much more convincing and important than the two of the latter, because we have an existence proof in the first case that it is indeed possible, whereas it is not clear what if anything follows from such unconstrained ‘thought experiments’ as are imagined in the latter two.) These people like to talk about instantiation rather than identity. On the other hand, more scientifically motivated accounts rooted in biology such as that of Darden or Bechtel and Richardson favor talk of functional localization rather than identity. See Darden, L.Theory Construction in Science: The Case of Genetics (Oxford: Oxford University Press 1991)Google Scholar; and Bechtel, W. and Richardson, R.C.Discovering Complexity: Decomposition and Localization as Scientific Research Strategies (Princeton: Princeton University Press 1992)Google Scholar. I am sympathetic with the latter kind of approach, but still feel the need for a kind of identity which falls somewhere in between type and token identities in its logical characteristics. What you want to know is what this (and other similar) instance(s) of this type is (are) identical with, but we are not committing ourselves to unqualified generalizations over all possible worlds which preserve the same functional equivalence classes. For a realistic account of scientific theorizing, we want a kind of context-bound type identity: not one that is expected to be valid across all possible worlds, but neither one which is bound rigidly to this particular single instance. It is a contextual generalization of uncertain but not too narrow scope, where the properties of the upper level thing are explained, ceteris paribus, by the operation of the spatio-temporally coincident lower level causal machine. The generalization has exceptions, as do all generalizations relative to their lower-level instantiations. (Donald Davidson was too parochial in boasting about the anomalousness of the mental — it’s anomalous at each level of organization, all of the way down).

31 It is tempting to think that this can’t be true for natural kinds, but I think it is rather true that we haven’t paid enough attention to the right kinds of more complex cases — and along with this (though I won’t do so here) to ask more carefully what functions we want our concept of a ‘natural kind’ to serve. An example of the complexities 1 would wish to consider is provided by ecological definitions of species types — where the type of organism is defined by the ecological niche that it fills — a kind of functional equivalence. Thus there are both marsupial and placental ‘squirrels’ and ‘dogs’ — though the distance to their common ancestors are great, and the two marsupials (or the two placentals) are closer relatives by evolutionary genealogy (and DNA sequence) than the two squirrels or the two dogs. Nor will it do to say that terms ‘squirrel’ and ‘dog’ only refer to categories of folk psychology and can’t be natural kinds, for these terms would enter into many regularities of behavior, and have genuine predictive and explanatory import — indeed, probably more — for most aspects of their behavior than any characterization derived from their genealogy or distances in a DNA sequence space. Finally, to say that natural kinds must have definitions in terms of intrinsic rather than functional properties would beg all of the most important questions. See also the last part of the discussion of the Brownian motion case in item 1 below for further discussion of what makes intrinsic properties important and their apparent absence for Brownian motion particles.

32 It obviously would not be for a functionally defined entity.

33 See Wimsatt, ‘Teleology and the Logical Structure of Function Statements,’ Studies in the History and Philosophy of Science 3 (1972) 1-80.

34 See my ‘Reductionism, Levels of Organization, and the Mind-Body Problem.’ See also H.A. Simon, ‘The Architecture of Complexity.’

35 See Haldane, J.B.S. ‘On Being the Right Size,’ reprinted in Nagel, E. and Newman, S.The World of Mathematics (New York: Simon and Schuster 1957)Google Scholar.

36 For a systematic discussion of the importance of size in the biological realm, see Knut Schmidt-Nielsen’s fine book, Scaling: Why is Animal Size So Important? (Cambridge: Cambridge University Press 1984).

37 See Piarceli, R. ‘Life at Low Reynolds Number,’ American Journal of Physics 45 (1977)3-11CrossRefGoogle Scholar.

38 This criterion is different from the compositional one, but has related presuppositions, and like any statistical property of collections, is further indirect evidence of the importance of the compositional criterion. It isn’t necessary because system properties — indeed, most of the interesting ones — needn’t be purely additive or aggregative functions of the properties of the parts, like an average is. The property of aggregativity — or its denial — is crucially connected with an important concept of emergence in which the higher level properties depend upon how the parts are strung together. This concept of emergence is consistent with reductionism or mechanism. (The conditions required for a system property to be an aggregate of the properties of the parts of the system — conditions on the ‘composition function’ relating system and parts’ properties — associativity, commutativity, inter-substitutability, linearity, and invariance under decomposition and reaggregation, turn out to be very useful tools in describing the modes of organization of complex hierarchically organized systems. See my ‘Forms of Aggregativity’ and ‘Emergence as non-Aggregativity.’)

39 There is an interesting and suggestive relation here between ‘average’ and ‘stereotype’ (an abstraction depicting an ‘average’ or distorted average) and level, where in this case level is broadened to include not only quasi-compositional level, but also social status or power relations. Different compositional or quasi-compositional levels are involved when a member or representative of a corporation relates stereotypically to an individual — say a customer, while the individual is forced to relate to the corporation according to its individual characteristics. The differential behavior of members of different (‘upper’ and ‘lower’) classes towards one another is legendary, and the stuff of novels. If the stereotypic or stereotyped object relates to the agent as an individual, this puts that individual at a “higher level.’ If both individuals are stereotyping each other, they are just ‘cogs’ in their respective institutional or social ‘machines,’ or ‘acting out their roles.’ There is an oft-observed confusion between ‘average’ and ‘stereotype’ or between statistical norm and some sort of evaluative norm in common thought, but what is interesting is how this maps onto the compositional, power, or status levels distinctions.

40 Lest one believe that any reduction in dimensionality should lead to a simplification in the observed behavior, I suggest a visit to Edwin Abbott’s classic Flatland, in which 2-dimensional creatures see very complex and confusing behavior of 3-dimensional objects passing through their 2-dimensional world. In fact, the predictive accuracy of a model is usually increased by increasing the dimensionality of the model — which is part of which makes levels such remarkable beasts. See also my discussion of Lewontin’s ‘dimensionality’ argument in the units of selection controversy (‘Reductionistic Research Strategies’).

41 Leo Buss and Walter Fontana, in “The Arrival of the Fittest: Towards a Theory of Biological Organization’ (unpublished ms), have recently been working on simulations of the evolution of life using symbolic biochemistries based upon expressions and rules of the X-calculus — expressions which can combine and operate one another. After a time, they found the spontaneous evolution of a subset of expressions which occupied a small (i.e., lower dimensional) subspace of the space of possible ^.-expressions, and whose interactions were governed by a grammar. Neither the expressions nor the rules for their interaction were built into their simulation at the start. What they have in effect done is generated the evolution of a level of organization, complete with entities and laws, in a different (and in this case, abstract) material, which has the important properties described here of a level of organization. This suggests that compositional levels of organization may in fact be an extremely general property of spontaneously evolved complex systems.

42 This suggests that ontological changes of centrally located thoeretical entities at a given level should differentially affect other entities and properties at that level most strongly, and be more weakly connected with other changes at other levels. This suggests interesting constraints on theoretical changes affecting superven-ience-like relations.

43 Of course, with intentional agents, categories in theories can acquire a causal role in the generation of behavior, and if the behavior involves the production of material systems, such categories or decisions using them can result in the generation or creation of physical, biological, psychological, social, and cultural order. But in this way, theories become parts of the physical world as well as lenses through which it is viewed. The interests and needs of human agents can become materialized in similar fashion, becoming instantiated through hardware and software technology, our choice of research projects, and of how they are to be pursued, producing (in Stuart Glennan’s fortuitous words) ‘changes both in the lens and in the picture it presents.’ In this way, the picture I urge combines elements of a constructivism in a broader-based realism. In this picture it may be extremely hard — not to mention, in most cases, pointless — to tease the aspects of construction and realism apart. Nonetheless, it is plausible to assert that theories will become more causally efficacious in that world to the extent that theoretical categories map accurately onto natural categories in the world — or onto cost-benefit approximations to them.

44 But see Waismann, F. ‘Verifiability,’ in Flew, A.G.N. ed., Logic and Language first series (London: Blackwell 1951), 117-44Google Scholar, for a rich and perceptive paper on levels written from the linguistic perspective, which (particularly in his accounts of the limitations of inter-level translation) makes many points I would agree with.

45 Indeed, I would argue that almost all robust entities are at levels, for reasons given in the next section. Here as elsewhere when I use terms like ‘most,’ or ‘almost all,’ I do not assume that the entities are counted, or even countable. (They could fail to be countable to a fallibilist either by being of a non-denumer-able infinity in number, or more paradoxically, by being finite, but not orderable in any compact rule-governed way, so that the only way to tell would be by doing an exhaustive survey of all cases.) In this or in most other such cases, when I say ‘most,’ I refer to the proportion among the cases sampled, on the assumption that they are representative — a judgment subject to the normal array of availability biases discussed by Tversky, A. and Kahneman, D. ‘Judgment Under Uncertainty: Heuristics and Biases,’ Science 185 (1974) 1124-31CrossRefGoogle ScholarPubMed.

46 Levins, R.Evolution in Changing Environments (Princeton: Princeton University Press 1968)Google Scholar

47 It does of course in the human realm, and for parallel reasons: counter-predictive purposive agents are the stuff of game theory, and not surprisingly, the one place game theory has found a home outside of the realm of human behavior is in evolutionary biology; for which, see Maynard-Smith, JohnGame Theory and Evolution (Cambridge: Cambridge University Press 1982)CrossRefGoogle Scholar.

48 Matching levels involves most obviously matching size scale and frequency dynamics parameters so that the main desiderata of the niche that the organism has chosen can be fulfilled. This will mean evolving with the behavior of the other organisms which are evolutionary factors as constraints — something which may sometimes call for matching size and frequency (most often for conspecifics), and sometimes for mis-matching one or the other or both (most often with prey or predators).

49 See Schoener, T. “The Ecological Niche,’ in Cherritt, J.M. ed., Ecological Concepts: The Contribution of Ecology to an Understanding of the Natural World (London: Blackwell 1990), 79-113Google Scholar, for a recent review.

50 Cf. the ‘constructional’ view of the relationship between organism and environment of Levins, R. and Lewontin, R. in The Dialectical Biologist (Cambridge, MA: Harvard University Press 1985)Google Scholar, the concept(s) of the ecological niche (T. Schoener, ‘The Ecological Niche’), and for an important and instructive extension of the concepts of niche and species to the evolution of theories and research traditions, see Douglas Allchin, ‘An Ecological Model of Theory Change: The Case of Oxidative Phosphorylation’ (PhD diss., University of Chicago 1991).

51 For a more technical exposition of some of the details, see Jeans, JamesAn Introduction to the Kinetic Theory of Gases (Cambridge: Cambridge University Press 1960)Google Scholar.

52 The still much shorter half-life of elementary particles should make it clear that the lifetime required for an object to count as a good object is level-relative. With this observation, then, we can formulate the problem more precisely as that the lifetime of the ‘clusters’ is not appropriate to — it is too short for — entities of that size scale. See item (n) below.

53 The converse does not follow — that anything given a functional definition is necessarily between levels. Chuck Dyke has also argued (in a personal conversation) that if we accept functional definitions of objects, there is nothing wrong with speaking of Brownian motion particles and their colliding assemblages as constituting a level. This seems to suggest either that functional definitions alone are not enough, or alternatively (perhaps suggested by the mental realm) that we need a more strongly connected set of interlocking functional definitions to be willing to reify a level on that basis alone.

54 In a recent unpublished paper, ‘Time for Less Essence? Intrinsic Properties, Time-Dependent Measurement, and the Concept of Molecular Structure,’ Jeffrey Ramsey has argued to a strikingly similar conclusion. His paper supports in a variety of ways the perspective urged here.

55 The usefulness of this kind of measure depends upon the widespread scale-in-variance of these fractions for different reactions over different size deviations from equilibrium — producing a recognizable exponential approach to the equilibrium state. The best known example is the ‘half-life’ of different radio-isotopes — the time it takes for half of their nuclei to decay, a different measurable constant for different isotopes. There are other measures (e.g., the infamous LD-50 — that dose which kills half of the relevant type of test organisms) which don’t have this exponential character: two LD-50s will probably kill all or nearly all of the organisms, not 3/4 of them.

56 See Lewontin, R. ‘Adaptation,’ Scientific American 239 (1978)CrossRefGoogle ScholarPubMed; reprinted in Sober, Conceptual Issues, on ‘quasi-independence’; and my ‘Units of Selection and the Structure of the Multi-Level Genome,’ in Asquith, P. and Giere, R. eds., PSA 1980 vol. 2 (East Lansing, MI: Philosophy of Science Association 1981), 122-83Google Scholar, for further discussion.

57 This is not quite true. I give conditions — characterized both formally and informally — under which going to the lower level is explanatory and conditions under which it is not in ‘Reductive Explanation.’ See especially the definition of ‘effective screening off in the appendix.

58 Van Valen, Leigh ‘A New Evolutionary Law,’ Evolutionary Theory 1 (1973) 1-30Google Scholar

59 See Maull, N. ‘Unifying Theories without Reduction’ (PhD diss., University of Chicago 1976)Google Scholar; my ‘Reductive Explanation’; and L. Darden and N. Maull, ‘Interfield Theories,’ Philosophy of Science 43 (1977) 44-64.

60 At still higher (e.g. planetary, solar, or cosmologica!) levels, this process seems to be reversed, for several complex reasons: many of the still higher level processes are driven by bulk or average processes at lower levels and thus tend to produce regular behavior, but some represent divergent processes producing chaotic irregularities whose effects we cannot characterize except in terms of fractal, and thus scale-independent patterns. Perhaps the absence of differential selection processes and predator-prey and parasitism networks, which ferret out any usable order while simultaneously generating designed unpredictabilities (h above) allows a less complicated dynamics, or perhaps it is equally or even more complicated, and we simply do not have yet the motivations to understand it or the tools to see it.

61 This is a qualitative remark. There is of course no reason to suppose that there should be this kind of relation.

62 Hugh R. Wilson, personal conversation.

63 Derived originally from ecology. Cf. Schoener, and also Allchin.

64 This is called ‘descriptive complexity’ in my ‘Complexity and Organization,’ and the preceding kind of complexity is called ‘interactional complexity.’

65 This is perhaps just a first approximation: I am unhappy with the implicit claim that ecological niches are confined to a single level. See item (i) above. Whether ‘predominately to a single level’ would do is another question; cf. Schoener.

66 von Üxkull, Jacob ‘A Stroll Through the Worlds of Animals and Men: A Picture Book of Invisible Worlds,’ in Schiller, Claire H. ed., Instinctive Behavior: The Development of a Modern Concept (New York: International Universities Press 1957), 5-80Google Scholar; and Nagel, T. ‘On What It’s Like to be a Bat,’ The Philosophical Review 83 (1974) 435-50CrossRefGoogle Scholar, are the best (and remarkably close) exemplars of this position.

67 See F. Lighthall, ‘Social Psychological Adaptation: Structures, Agendas, and Problems’ (unpublished ms).

68 The terms ‘descriptive complexity’ and ‘interactional complexity’ refer to the complexity of mappings of object boundaries from one perspective to another, and to the strength and structure of causal interactions between variables and parts in different perspectives. They are defined and discussed in detail in my ‘Complexity and Organization.’

69 The path here is fraught with error and tempting but dangerous inferences. I think that the tendencies are real, but that there are exceptions to everything said in the rest of this paragraph. All of the kinds of qualifications about finding genuinely aggregative properties in nature urged in my ‘Emergence as non-Ag-gregativity’ apply here. At present, it is important to regard this claim as a statement about discovery heuristics or as a statement of psychological tendencies. I think that more can be said which is sound, but a lot more careful exploration is required first.

70 Nancy Cartwright, ‘Fundamentalism vs. the Patchwork of Laws,’ lecture and draft ms, The University of Chicago, 22 October 1993.