Stanley N. Salthe

Ph.D. Zoology, 1963, Columbia University.

Professor Emeritus, Brooklyn College of the City University of New York

Visiting Scientist in Biological Sciences, Binghamton University

Associate Researcher of the Center for the Philosophy of Nature and Science Studies of the University of Copenhagen.

e-mail address: ssalthe [ at ]
Telephone: 607-467-2623
Mail Address:
    42 Laurel Bank Avenue
    Deposit, New York 13754

On-line papers:

Fields of Interests

     Biology theory
     (Non-mathematical) Biology theory, focusing on development and evolution, and their relationship. I use operational definitions for development (predictable directional change) and evolution (the irreversible accumulation of historical information = individuation), which allows these concepts to be generalized.
      I am a critic of Darwinian evolutionary theory -- which was my own erstwhile field of specialization in biology. My opposition is fundamentally to its sole reliance on competition as an explanatory principle (in a background of chance). Aside from being a bit thin in the face of complex systems, it has the disadvantage, in the mythological context of explaining where we come from, of reducing all evolution to the effects of competition. I see this as morally vicious, if understandable in the genealogical sense that it serves as a myth congenial to Capitalism. Motivated thus, I have found that upon close examination there are many limitations on the power of Darwinian explanations. For example, it would appear that population genetics theory has been (for over 60 years) limited, IN GENERAL, to modeling changes only in single traits (see "Analysis and Critique of the Concept of Natural Selection" [here]). This limitation is no conceptual problem if we place Darwinian explanation in the context of developmentalism (see below), but then natural selection can no longer be the sole factor in evolution, but must function as a handmaiden to self-organizing processes, as suggested by David Depew and BruceWeber in Darwinism Evolving.
      I note further that the idea of natural selection must be among the fittest of ideas in our social climate. It has spread from evolutionary biology to immunology, developmental biology, psychology, economics, philosophy of science, sociology, information science, etc. It appears to be an idea that can adapt to any material whatever, driving out, in the process, ideas that were native in the various discourses (like instructional models in immunology). Being materially empty, it appears capable of explaining almost anything, and so we need to be cautious about its use. Is it a Borgesian cognitive poison?

      The perspective that all material systems undergo a development from immature through mature to senescent (which is followed by recycling or rejuvenation). In order to see this, one has to look at very general aspects of systems, such as thermodynamic and information theoretic properties. A key supposition of developmentalism is that if a material system is interpreted as evolving, then it must be undergoing developmental changes as well. I use the following general definitions: development is made up of predictable directional changes (or, deleting the observer, constitutive changes); evolution is the accumulation of historical information. The dialectical model of Fichte and Hegel offers a general approach to development in the context of natural philosophy, where it may for some purposes be useful to construct development as a subjective process -- see internalism, below.

      This neologism (for information dynamics) refers to a combination of thermodynamics and information theory. Based in the formal identity of Boltzmann's interpretation of physical entropy (as disorder) and the Shannon / Wiener formulation of information carrying capacity (as variety) (see "The Mutual Implication of Physical and informational Entropies" [here]), my own version of it advances the plausible inference (supported by data from many different fields) that the number of informational constraints necessarily increases during the development of dissipative structures as they mature and senesce. Thermodynamically, development of individual dissipative structures follows a canonical pattern of mass-specific energy dissipation increase followed by a decrease into senescence, as systems appear to become entrained by the minimum entropy production principle of Ilya Prigogine (A.I. Zotin, and of Sven Jørgensen as well). I postulate this decline to result from an increased rigidity imposed upon systems by information overload, thus interpreting senescence fundamentally as a general constraint of materiality.

      Thermodynamics also has a role in evolutionary theory, signaled by the maximum entropy production principle (MEP) of Rod Swenson (or, equally, the maximum energy gradient dissipation principle of Eric Schneider and James Kay), which has now been shown to be a basic physical principle by Roderick Dewar. My own way of putting this is that form facilitates entropy production increase locally by way of catalyzing the degradation of energy gradients. Thus: In the material world, gradients, to the extent that they are steep, tend to generate, or attract and associate with, dissipative structures that will degrade them.) So then the presence of form in the universe can be explained as a result of entrainment by the Second Law of Thermodynamics (here I am bearing in mind Aristotle's complex model of causality, by seeing the Second Law as the ultimate final cause of form -- see the figure [here ]: Where? What? When? Why?). This should be viewed in light of the cosmological views of David Layzer, Stephen Frautschi and Peter Landsberg, which posit that matter precipitated from energy because the expansion of the universe in the Big Bang was too fast for energy to maintain equilibrium distribution. In its own random search for equilibrium distribution, matter then collides contingently, forming larger chunks that are even further away from global equilibrium, raising the intensity of the universal tendency towards thermodynamic equilibrium even further. Form appears next, prevailing according to its ability to facilitate entropy production (viz. Bénard convection). So, we have, using set theoretic formalism: {energy -> {matter -> {form -> {organization}}}}.(See the figure [in pdf here] "Levels of Reality and their Production").

In this understanding aspects of organic evolution can be explained which have no neoDarwinian explanation (other than chance) -- e.g., the evolution of homeothermy, or why mammals and birds generally succeeded reptiles, and why teleost fishes succeeded more primitive forms, as well as why invertebrates developed mouthparts. As an evolutionary principle, MEP posits that forms that tend to replace others in evolution are those, ceteris paribus, which better enhance the degradation of energy gradients. This applies to the immature stages of dissipative structures, not to their senescence, which is characterized instead by specific entropy production minimization and gross entropy production levelling-off.  For more see [here ] text, The Natural Philosophy of Entropy

      Natural Philosophy
      Natural Philosophy (or the philosophy of nature), is a developmental view of evolutionary processes, from cosmic evolution to organic (biological) and cultural evolution (see "Natural Philosophy: Developmental Systems in the Thermodynamic Perspective" [here]), now including, e.g., MEP (see "The Natural Philosophy of Ecology" [here]). Its antecedents lie in the Nineteenth Century -- with Comte, Goethe, Peirce, Schelling, Spencer, etc. It is a perspective that constructs a science-based story of where we came from and what we are doing here (see text, Becoming, Being and Passing). It is sometimes known as General Evolution, and encompasses cosmic, organic and cultural evolutions. Its goal is an intelligible creation myth (using "myth", not as a pejorative term, but as it is used in ethnography).

      Postmodernism: by this I mean a viewpoint critical of the realist pretensions of any universalist, totalizing discourse, including science, natural philosophy, and the Abrahamic faith religions. It takes seriously the dichotomy: actual / real. That is, while the actual world is that which you can bump into, or feel as a toothache, or as a frisson during a ritual, the real world is a global product of discourse, and consists in texts, inscriptions, models (like MEP and hierarchy theories), films, equations, experimental setups, simulations, computer software, symbols, etc. It is the home of the laws of Nature and the laws of matter, as well as of the gods. This real world has been the concern of externalist discourses, from theology to science and postmodernism itself -- wherever the observer sits outside the system being studied. The actual world is of concern to internalist discourse -- see below.

      I take materialism to be a perspective at the intersection of, e.g., phenomenology, operationalism, autopoiesis discourse, pragmatism. It seeks intelligibility. I believe that the primary phenomena that motivate materialism are those of restriction and limitation. The material world imposes friction, delay upon messages, ageing -- in short, material embodiment is the reason why nothing can be obtained, constructed or cognized instantaneously, or preserved forever. The material world is not co-extensive with the physical world, which, as a more general integrative level (or more generally present realm), can involve superconductivity, global conservation (as in the first law of thermodynamics), quantum vacuums with frictionless communication between electrons, and so on. Indeed, electrons (and black holes, genes, and chemical bonds) would be systems conceived of as if in the physical world, but not of the material world, which has connections to internalism. Materialism is a perspective taken by active, subjective agents, therefore its categories are in no way projected upon the 'real' world 'out there', which is the object of externalizing physical discourse. And materialism has nothing to say about whether or not there is a spiritual world, as is usually thought. Perhaps dissatisfaction with the material world (as I have described it here) is itself a clue to why we have the presence of spirituality! In other words, classical materialism -- the metaphysical stance that there is nothing in the world but matter in motion -- is not entailed by the view of materialism embraced here.

     Hierarchy Theory:
      Hierarchy Theory (see also "Principles of Hierarchy Theory" [here]) encompasses both the scalar hierarchy of nested extensions (represented as scalar levels, as in [ecosystem [population [organism ]]]), and also the specification hierarchy of ordered intensional complexity, modeled as integrative levels, as in the following example:

{ physical world  { chemical world { biological world { social world { mental world }}}}}

Differences in scale of objects or processes are generally measured in orders of magnitude, while integrative levels are apprehended when it is discovered that some discourse is insufficient to deal with certain phenomena, as when we find it impossible to understand biological systems using only chemical discourse. This requires us to make a new discourse, signifying a new integrative level.
      The specification hierarchy is fundamentally a pattern of thought, congenial to Natural Philosophy, and requires that we stipulate an observer in the inmost level, to whom the system is relevant. So it is not an objective approach, as the scalar hierarchy can be.  The scale hierarchy could even be said to have a satisfactory mechanistic interpretation.
      The specification hierarchy also supplies a model of development, with the inmost level then being a unique individual material embodiment of the various classes in the outer levels, as in {dissipative structure { organism { animal { mammal { hominoid { human { male { white { middle class { ageing { Stan Salthe }}}}}}}}}}}
This form, as a model of development, originated with Aristotle, but it was used prominently by Linnaeus merely to signify new taxonomic levels. As a model of development, it can also serve as the basis for a generation myth associated with Natural Philosophy, when the integrative levels are taken as stages of development of the universe, as in {physical process -> {chemical affinities -> {biological form -> societal organization}}}}.

       Another view of causal complexity comes from Aristotle, with his four causal categories (see figure "Where? What? When? Why?" [here]).

      On the problem of conflating hierarchies in particular examples. [This section added November 2002].
      It must be stated first that scalar and specification hierarchies are theoretical constructs coming from particular historical backgrounds -- the former from Middle European systems thinking, via Bertalanffy and Paul Weiss, the latter from the Marxist tradition, notably through Joseph Needham. Most actual systems can be analyzed from either point of view, and this has led to conflating these structures, and even to statements that actual examples do not clearly exemplify either of these systems. In the interest of clarity of thinking, we should examine an example that invites this problem.
      Consider the scale hierarchy: [ population [ organisms [ cells ]]]. [ ] means screening off by size and dynamical rate differences -- it is a cutting off or delimiting marker of dynamical boundaries in the formalism of parts and wholes. In this model of extensional complexity we see that a population contains organisms, which contain cells, nested within them. It is also implied here that organism dynamics are constrained by boundary conditions established by population dynamics (that is, are indirectly affected by results of these dynamics), and that organism dynamics in turn impose boundary conditions upon cell dynamics, but the dynamics at each scalar level are screened off from each other by order of magnitude differences in rates of change, and so cannot directly interact. As well, constraints from higher to next lower level are not functionally transitive to the next level below that. Each level mediates information between contiguous levels, but filters and reworks it. So the scale hierarchy is characterized only by first order constraint effects (except for perturbations, as when lightning from a much larger scale strikes a tree, whose dynamics occur at a lower scale).
      Now consider the specification hierarchy: { chemical dynamics { organism dynamics { social dynamics }}}. In this model of intensional complexity { } implies the local addition of new constraints upon the dynamics of the lower levels (which would be more generally present in the world). The symbol { } shows the presence of a subclass in the model. The creation of a new subclass is an increase in the specification of local constraints because, formally (from set theory), some of what is the case at the most general level continues to be so in all subclasses, but not the reverse. That is, some of the lower level dynamics here are transitive in toward the higher levels. In this model of intensional complexity we see that some chemical dynamics (at some locale) become integrated under biological constraints, and while some biological dynamics get to be integrated under social constraints, so do the chemical ones. Chemistry is directly present at both the organism and social levels.
      So, both systems have the same higher levels imposing constraints on the dynamics of the same lower levels. Conflation is a danger here. Yet the logic of each hierarchy is different, and so we need to consider what we are trying to accomplish with our hierarchical model. In the scalar system, [ ] is a black box to all higher levels -- a barrier between, or chunking, of processes, with only non-dynamic, informational constraints impinging from one level to the next, via some process of transduction. In the specification system, { } is a selector such that some of the lower level dynamics pass through to the next (and some further) higher level(s). { } is a selectively transparent one-way filter. For example, at the level where social dynamics are taking place, selected chemical dynamics are also "visible", in their effects upon the social dynamics, along with the promotion or harnessing of these dynamics by social ones.
      Note that in the scalar system new levels would emerge between existing ones whenever some constraints from the higher level have the effect on a receptive lower level of selecting (entraining) some of the lower level dynamics to chunk into patterns that change more slowly than do the lower level dynamics themselves (but not as slowly as the upper level ones), and where some orders of magnitude still separate all three. This is a differentiation model, with levels potentially being intercalated as long as there is sufficient rate difference between the dynamics of any upper and lower level. The three level image here is crucial to the sense of stability that inheres in the scale hierarchy. No level's dynamics can be reduced to those of any other level because of anchoring by the third level that was involved in its emergence and which continues to exert maintenance constraints. This signals a major difference from the specification hierarchy.
      In the specification hierarchy new levels emerge at the top of the hierarchy ( { chemical dynamics --> { biological dynamics --> {social dynamics}}}). This is functionally a two level hierarchy, with any level being ready to either collapse back into a lower one, or to give rise to a new one. Development of new, higher levels is mediated by the inevitable acquisition of new informational constraints in material systems -- a process favored by the Second Law of thermodynamics (and which some call a Fourth Law).
      So, the scalar hierarchy embodies stability, models ongoing processes, and forms a kind of Minkowski block universe of nested, differently scaled moments, where interpolation of a new level serves the continued stability of the whole, as a homeostatic mechanism. Instead, the specification hierarchy models change, as some lower level dynamics become harnessed by emerging higher level constraints, and then some of these dynamics might be pulled into affairs at even higher levels. The levels partially interpenetrate from the bottom up, with scale difference not acting as a functional category, as processes at the lower levels become entrained by (integrated into) processes at newly emerging higher levels (as, for example, when the physical process of diffusion becomes regulated by the circulatory systems of living systems). So we see that the two hierarchical formalisms do not serve a single function; one models stability, the other change. Therefore, it is not a matter of which one is more veridical to actual systems, but of what a modeler is interested in understanding. We should now examine a randomly chosen particular example of the above hierarchies.
      Suppose we examine a celebration (or ritual of some kind). Social dynamics impose various rules of behavior upon the individual biological people. That is , some biological urges and needs are suppressed for the duration of the celebration, while others, perhaps digestion, continue as they would under most routine social constraints. For the most part, the organism, we might say, is "unaware" of the event as such. Not entirely, however, as some non-routine activity may be required, such as, say, dancing -- an entrainment by socially approved rhythms (and not others -- no minuets at a rock concert!). Whatever special requirements are imposed upon the organism will become reflected in the mix of constraints (by way of hormones, nerve entrainments, etc.) imposed upon some of the organism's cells. Going the other way, after some dancing, the oxygen debt incurred by muscle cells, gets reflected in heavy breathing as its mass effect within the organism triggers various sensors and actions. This is likely to be reflected as well at the social level in the traditional duration of given dances. If social use of "stimulants" is involved, these will have effects upon the neurons from the chemical level, as well as on other cells and tissues, leading to altered behaviors by way of changing the mix of possibilities generated at the cellular level. We could go on and on, but we need to reflect upon the purpose of our inquiry before getting lost in details.
      The scale hierarchy is primarily concerned with system stability, with understanding an event like this as a structure of relations at the different levels during some representative moment. How is the whole event held together from level to level? Why doesn't it just fly apart? Analysis in this mode would result in a fairly mechanistic model, with dynamical possibilities generated at the cellular level being selected at the organism level, and behavioral possibilities generated there being selected by the social level. Lower levels propose a mix of possibilities, higher ones dispose, by deploying some of the possibilities in an organized way. Higher ones may also attempt to bias the mixes of possibilities at lower levels by deploying, say (in this case), stimulants. One concern of the scalar approach is to oppose reductionism, by showing that all levels are fully required for any manifestation to occur.
      The specification hierarchy is more concerned with change. How does one stage in the celebration develop into the next? How does information from a lower level make itself felt at increasingly higher levels, thereby explaining why the social system has drawn in the likes of stimulants, fragrances and other low level biasing devices? The system might be examined from just the cellular vantage point, showing how general cellular behavior is increasingly entrained into narrower and narrower sets of possibilities by the context of the celebration, or how chemical properties are elicited and focused by the social event. The analysis would result, not in a nested set of events or dynamics at different scales, but in a series of arrows indicating what influences what, with feedbacks between levels, and so on, generally moving irreversibly. It would try to show the points of introduction of new constraints that destabilize the system, which then reorganizes around the next stage (rather than collapsing back to an earlier one)

      From Charles Peirce, this is the general study of signs and their interpretation, as well as of the process of semiosis, or, indeed -- the study of the construction of meaning. It is not restricted to linguistic signs, as in the semiology of Saussure. The adjective "general" implies that semiosis is more general than human sign use (anthroposemiosis), and many thinkers have extended the doctrine of signs to biology (biosemiosis), encouraged especially by the inviting situation of genetic systems (as in the works of Jesper Hoffmeyer and Marcello Barbieri), as well as by the more obvious animal behaviors (initiated in the seminal work of Jacob von Uexküll). A few of us have suggested that semiosis must be even more general, on the principle that nothing that exists at one integrative level, say the biological, was without precursors, and so we can postulate physiosemiosis (of John Deely) as well, applying to any dissipative structure, giving us a general pansemiotic position. While digital signs operate in a fully semiotic situation, analog signs may function in vaguer semiosic systems. The key here is to seek relevant systems of interpretance (see figure: System of Interpretance [here ]). Physiosemiosis interprets the world as triadic relations, even in the absence of referentiality. Basically this means that its analysis takes into account not only an object (or system), but its interactions with others as mediated by a context. All three aspects -- Peirce's Firstness, Secondness and Thirdness -- must be taken into account.
      Peircean semiotics is irreducibly triadic -- sign / object / interpretant -- the latter being the product of a system of interpretance, with the sign being a co-product of the object and the system of interpretance. This means that semiotics is a subjective discourse, stipulating particular observers. There can be no general meanings. A sign means something to someone. So, if we, as observers, postulate that some chemical signifies food to a snail, not only do we realize that it may not do so to other animals, but it also may not seem do so for another kind of observer of snails (say thrushes who eat them).
      Taking this approach implies a critique of science as it has been, the purpose (social role) of which has been to deliver knowledge that could be used in the control or prediction of natural phenomena -- in the search for power over Nature. In that context, Nature is best seen as a meaningless spin of matter in motion (as in traditional materialism), leaving us a free hand, unencumbered by gods or traditional values. Bringing semiotics into science makes sense, in my view, only as part of an attempt to use science instead as an avenue for understanding the world -- that is, in order to bring it closer to Natural Philosophy.
      As noted by Floyd Merrell, signs grow. That is, they are qualified by other signs in an indefinite chain of interpretants-as-new-signs. In this way semiosis intersects development (as described above). Semiosis is a developmental process.

      Natural phenomena are similar to each other in some respects, and differ in others. Difference is a conceptually trivial concept. One can always find differences between any two discriminated items, and, failing this, can mark one to make it different from the other. In Biology, cladistics provides techniques for determining precedence in respect to the acquisition of differences, and neoDarwinism attempts to provide a kind of explanation for how such differences might have been acquired. In both of these discourses, and, I believe, in any historicist discourse, similarity is reduced to just the absence of difference. That is, it is trivialized. But similarity is, I think, the deeper problem.
      Similarity is semiotic, in that it necessarily involves an observer or system of interpretance (SI). Iconic signs, like shadows, possess similarity to their objects for a given SI. Like all signs, they are co-produced by object and SI. But similarity as a general problem has to do with whether two objects in themselves are similar, not whether a sign happens to be iconic. Semiotically, this would mean that two objects must have the same counterstructures (von Uexküll) with respect to a given SI. Such objects may serve as metaphors of each other.
      When this is the case there arises a need to explain the similarities. The historicist explanation is that, if things are similar now, they must have been the same in the past, since history is the acquisition of difference. This does not explain the primordial sameness unless it can be attributed to a single ancestral individual, whose properties then need no explanation other than chance. This kind of explanation fails utterly in the face of, e.g., similar cloud formations, or similarities among any other abiotic dissipative structures -- tree forms and vortices, for example. With these, as everywhere, history just produces differences. The physical approach to these similarities is to claim that such phenomena were informed by the same initial and/or boundary conditions (that is to say, the same external environmental conditions) during their formation, and so turned out similar. For very simple systems under experimental conditions, this is an adequate explanation, but becomes increasingly implausible as similarity unites more complex objects in natural situations, many of which are found in biology. Also, the physical approach begs the question as to why systems in the same environment may become similar from different beginnings. In biology this is the problem of convergent evolution, producing ecological vicariance, as well as similar vegetations and biomes, in different regions.
      What is needed is a positive tendency toward similarity. We have good mathematical models of such tendencies in the attractors of dynamical systems. These can also serve to model the structures of classical structuralism. My view of structures is that they are unchanging universal tendencies with similar ontological status to universal physical constants. Like these, they would have been frozen in early in the Big Bang, and will not change for its duration. In a Bang / Crunch scenario, each succeeding Bang would organize its own structures and constants. Structures neither develop nor evolve, but material systems that can access them do. So some structures may never become accessed because material systems that could become entrained by them have been excluded by history. Some structures, like the branching tree, can be accessed by quite simple systems, but others would require both complexity and complication. Deep structures are universal potentialities which reflect the global organization of a particular universe. They are internal to a given universe, and so could not be reviewed or enumerated externally (see Internalism, below). One way to think of them would be as sets of informational constraints, many of which were reduced early in the Universe. When material systems develop that have reduced constraints that are like some of those in a deep structure, that system is then entrained toward reducing, by materially constructing, constraints that would complete the form in question during its development.
      So, any given material phenomenon or system has some similarity to others that are entrained by the same structural attractors, as well as differences that can be attributed to historical accidents. The task is to separate these by way of comparative study. As an individual system continues to endure, it is likely that its own history comes to be more important to its form, and so it becomes increasingly individuated from others attracted by the same structures. It is also possible, however, that, because information gradually accrues to a system as it ages, it may at some point become complicated enough to access a previously dormant (for it) or weak attractor, pulling it in a new direction. For any given material system the pull of structures ranges from strong to very weak, depending on its form and behavior. Structural attractors act as one kind of final cause. (See text "Purpose in Nature" [here ])

      This is a newly emerging point of view in science, with few antecedents, which include phenomenology, the thinking of J.J. von Uexküll, and the autopoiesis model of Maturana and Varela. Current major thinkers include Koichiro Matsuno, Yukio-Pegio Gunji, Otto Roessler and George Kampis. My own perspective on this is that internalism becomes necessary if we try to make a science which begins with the fact that we are inside, as participants in, the universe that we are studying. Internalism applies to such advanced technological situations as cosmological knowledge in the face of the finite speed of light (we cannot get outside the universe, or see it whole) and operationalism, as well as to the situation of a newborn infant trying to manage in the world. Internalism is a viewpoint that accepts in advance limits to knowledge, and any viewpoint expressing limitations, like Herbert Simon's "bounded rationality" is internalist. The problem of waste disposal is an important currently visible internalist predicament.
      Matsuno has been trying to examine the most reduced internalist situations possible in a search for principles. Here we can place the internal predicament of a newborn infant, living in the present progressive tense, with little stored record to aid it. I focus on this situation because it brings to the fore the important notion, from Charles Peirce, of vagueness. All aspects of nature are to some degree vague, while our discourses -- especially natural science and mathematics -- try to be as explicit as possible. This mismatch is another reason to try to advance an internalist science. This has been begun in a small way using logics that forgive the law of the excluded middle, like fuzzy logic, dialectical and trialectical logics. But in these logics, while set membership is unclear, set definition is still crisp (second order fuzziness begins to atteck this limitation). This is not vague enough to model the actual world as it appears.
      Stated in other words, the internalist project can be viewed as an attempt to model immature systems, for which the explicit descriptions of science are inadequate. The immature situation is vague, generative, and with relatively large evolutionary potential. The importance of this latter fact may be grasped by considering that, biologically, humans can be viewed as neotenic apes. Evolution has here not taken off from, or extended, mature stages, but has backed up and worked from the fetal situation. Some have even argued that most organic evolutionary progress (a notion rejected by neoDarwinians) has come about in this way. I believe that we will have poor understanding of evolutionary progress without an internalist science.  For more see text, Internalism Summarized [here ]

Major Publications:

Evolutionary Biology (a textbook). New York, 1972; Holt, Rinehart and Winston.

Evolving Hierarchical Systems: Their Structure and Representation. New York, 1985; Columbia University Press. (book description)

Development and Evolution: Complexity and Change in Biology. Cambridge, MA, 1993; MIT Press. (book description)

Evolutionary Systems: Biological and Epistemological Perspectives on Selection and Self-organization. Dordrecht, 1998; Kluwer Academic Publishers. (co-editor with Gertrudis Van de Vijver and Manuela Delpos). (book description)

The Evolution Revolution: What Evolution Means for Biology, Science, and Metaphysics.  (co-author with Horace L. Fairlamb).