Proponents of the standard evolutionary biology paradigm explain human “altruism” in terms of either nepotism or strict reciprocity. On that basis our underlying nature is reduced to a function of inclusive fitness: human nature has to be totally selfish or nepotistic. Proposed here are three possible paths to giving costly aid to nonrelatives, paths that are controversial because they involve assumed pleiotropic effects or group selection. One path is pleiotropic subsidies that help to extend nepotistic helping behavior from close (...) family to nonrelatives. Another is “warfare”—if and only if warfare recurred in the Paleolithic. The third and most plausible hypothesis is based on the morally based egalitarian syndrome of prehistoric hunter-gatherers, which reduced phenotypic variation at the within-group level, increased it at the between-group level, and drastically curtailed the advantages of free riders. In an analysis consistent with the fundamental tenets of evolutionary biology, these three paths are evaluated as explanations for the evolutionary development of a rather complicated human social nature. (shrink)

Even today, a century after the publication of the “Origin of Species”, current zoological literature often reveals an insufficient grasp of the implications of the now generally accepted view that it is natural selection that confers direction on the evolutionary process.This is, in part, due to a reaction against oversimplified teleology and against Lamarckism. In rejecting Lamarck's thesis that the activities of an animal directly affect its hereditary characters it is frequently assumed that this implies that such activities (...) are irrelevant to the study of evolution. This is a non-sequitur, for activities may affect evolution not directly, through heredity, but indirectly, by influencing the direction of the selective forces impinging on the organism. Reasons are given for concluding that changes in habits and behaviour frequently precede structural change and, in fact, determine the direction of the latter.As an example of a concept which deserves a more evolutionary treatment than it commonly receives, the subject of neoteny is considered. It appears that failure to think in terms of the selective forces involved has frequently led to error. An analysis in functional terms is made of the theory that the chordates represent secondarily glorified sea-squirts and it is concluded that this idea is unlikely to be correct. The characteristics of man that are commonly considered to be neotenous are also discussed. It is concluded that a facile and unanalytical application of the label “neoteny” to many of the evolutionary changes involved has tended to obscure rather than to clarify their significance: the neotenous features of man are not those that have been of primary importance in human evolution, but are secondary to the acquisition of new characters which are not to be found in either the adult or the young stages of any other primate.Aujourd'hui, un siècle après l'apparition de l'Originedes Espèces, la conviction est presque générale que la sélection naturelle dirige le procès de l'évolution. Néanmoins, les publications zoologiques actuelles révèlent souvent une compréhension insuffisante de ce qui en résulte.Ceci doit en partie être considéré comme réaction contre une téléologie simpliste et contre le Lamarckisme. En rejetant la thèse de Lamarck, que les activités d'un animal ont une influence directe sur ses caractéristiques héréditaires, on admet fréquemment que de pareilles activités n'ont rien à voir avec l'étude le l'évolution. Cependant, une telle conclusion n'est pas justifiée, car les activités peuvent influer sur l'évolution non pas directement, par la voie de l'hérédité, mais indirectement en agissant sur la direction des forces sélectives que l'organisme rencontre. Des raisons ont été données qui mènent à conclure que des changements dans les habitudes et dans le comportement précèdent maintes fois le changement structural et même déterminent la direction de celui-ci.Comme exemple d'un concept qui mérite un traitement plus évolutionniste qu'il ne reçoive en général, la néoténie a été examinée. Il paraît que l'on a fait beaucoup d'erreurs en ne tenant pas compte des forces sélectives engagées. Une analyse au pointde-vue de la fonction a été appliquée à la théorie que les chordées ne sont que des ascidies néoténiques transfigurées par après, et il s'ensuit que cette idée n'est probablement pas correcte. Aussi les caractéristiques de l'homme généralement regardées comme neoténiques ont été discutées. Il en résulte que, en désignant légèrement et sans analyse plusieurs changements évolutionnaires comme néoténie, on a plutôt obsurci qu'éclairci leur signification. Ce ne sont pas les traits néoteniques de l'homme qui ont joué le rôle principal dans l'évolution humaine; au contraire, ils n'apparaissent qu'après l'acquisition de quelques nouvelles caractéristiques qui ne se trouvent ni dans l'adulte ni dans les phases plus jeunes des autres primates.Sogar heutzutage, ein Jahrhundert nach dem Erscheinen der „Origin of Species”, zeigt die jetzige zoologische Literatur oft eine unzulängliche Einsicht in die Folgerungen, zu denen die jetzt allgemein akzeptierte Annahme leitet, dass die natürliche Selektion die Richtung des Evolutionsprozesses bedingt.Dies ist teilweise zu sehen als eine Reaktion gegen eine einseitige Teleologie und gegen das Lamarckismus. Bei der Ablehnung der TheseLamarck's, dass die Aktivitäten eines Tieres einen direkten Einfluss ausüben auf seine erbliche Konstitution, nimmt man oft an, dass dies bedeutet, dass derartige Aktivitäten demnach nichts zur Sache tun bei dem Studium der Evolution. Zu einer derartigen Konklusion ist man jedoch nicht berechtigt, denn, obwohl die Aktivitäten die Evolution nicht direkt beeinflussen können mittels der Erblichkeit, so können sie dies jedoch indirekt, weil sie die Richtung der selektiven Kräfte, welche auf das Organismus einwirken, bestimmen. Es werden Argumente gegeben, welche die Konklusion rechtfertigten, dass Änderungen in Gewohnheit und Verhalten oft Strukturänderungen vorhergehen und tatsächlich die Richtung dieser letztgenannten bestimmen. Die Neotenie wirdt als ein Beispiel eines Begriff betrachtet, welcher eine mehr evolutionäre Behandlung verdient als bisher geschehen ist. Es ergibt sich dass man viele Irrtümer hat gemacht, indem man den betreffenden selektiven Kräften keine Rechnung getragen hat. Eine Analyse der Theorie, welche die Chordaten als neotenische Ascidien betrachtet, wird von einem funktionellen Gesichtspunkt aus durchgeführt. Daraus scheint der Schluss berechtigt, dass diese Theorie falsch ist. Auch werden die menschlichen Kennzeichen, welche gewöhnlich als neotenische betrachtet werden, besprochen. Die Konklusion lautet, dass, wenn man leichtfertig und ohne genügende Analyse den Zettel „Neotenie“ für mancherlei evolutive Änderungen anwendet, man die richtige Bedeutung dieser Erscheinung vielmehr verdunkelt als aufklärt: nicht die neotenische Kennzeichen des Menschen sind am wichtigsten in seiner Evolution; in Gegenteil sie erscheinen nur sekundär, nachdem die neuen Kennzeichen, welche sich weder in den Erwachsenen noch in den jüngeren Stadien von den anderen Primaten finden lassen, erschienen sind. (shrink)

Human intentional action, including the design and use of artifacts, involves the prior mental representation of the goal (end) and the means to achieve that goal. This representation is part of the efficient cause of the action, and thus can be used to explain both the action and the achievement of the end. This is intentional teleological explanation. More generally, teleological explanation that depends on the real existence of a representation of the goal (and the means to achieve it) can (...) be called representational teleological explanation. Such explanations in biology can involve both external representations (e.g., ideas in the mind of God) and internal representations (souls, vital powers, entelechies, developmental programs, etc.). However, another type of explanation of intentional action (or any other process) is possible. Given that an action achieving a result occurs, the action can be explained as fulfilling the necessary conditions (means) for that result (end), and, reciprocally, the result explained by the occurrence of those necessary conditions. This is conditional teleological explanation. For organisms, natural selection is often understood metaphorically as the designer, intentionally constructing them for certain ends. Unfortunately, this metaphor is often taken rather too literally, because it has been difficult to conceive of another way to relate natural selection to the process of evolution. I argue that combining a conditional teleological explanation of organisms and of evolution provides such an alternative. This conditional teleology can be grounded in existence or survival. Given that an organism exists, we can explain its existence by the occurrence of the necessary conditions for that existence. This principle of the 'conditions for existence' was introduced by Georges Cuvier in 1800, and provides a valid, conditional teleological method for explaining organismal structure and behavior. From an evolutionary perspective, the conditions for existence are the range of boundary conditions within which the evolutionary process must occur. Moreover, evolutionary change itself can be subjected to conditional teleological explanation, because natural selection theory is primarily a theory about the relation between the conditions for the existence of organisms and the conditions for the existence of traits in populations. I show that failure to distinguish representational from conditional teleological explanation has confused previous attempts to clarify the relation of teleology to biology. (shrink)

Social learning mechanisms are usually assumed to explain both the spread and the persistence of cultural behaviour. In a recent article, we showed that the fidelity of social learning commonly found in transmission chain experiments is not high enough to explain cultural stability. Here we want to both enrich and qualify this conclusion by looking at the case of song transmission in song birds, which can be faithful to the point of being true replication. We argue that this high fidelity (...) results from natural selection pressure on cognitive mechanisms. This observation strengthens our main argument. Social learning mechanisms are unlikely to be faithful enough to explain cultural stability because they are generally selected not for high fidelity but for generalisation and adjustment to the individual’s needs, capacities and situation. (shrink)

Abstract. Since Darwin, scholars have contemplated what our growing understanding of natural selection, combined with the fact that great suffering occurs, allows us to infer about the possibility that a benevolent God created the universe. Building on this long line of thought, I develop a model that illustrates how undesirable characteristics of the world (stylized “evils”) can influence long-run outcomes. More specifically, the model considers an evolutionary process in which each generation faces a risk from a “natural (...) evil” (e.g., predation, disease, or a natural disaster) subsequent to a basic resource allocation game. This allows both resource allocation and the natural evil to influence the number of surviving offspring. As the model shows, when the risk from the natural evil can be mitigated through the benevolent behavior of neighbors, the population may have increasing benevolence as a result of (1) greater risk from the natural evil and (2) a greater degree to which selfish individuals transfer resources to themselves in the resource allocation game. The main implication is that a world with evolutionary processes (in contrast to a world of static design) can allow two factors that have traditionally been considered “evils”—namely, the indiscriminate cruelty of the natural world and the capacity for humans to harm each other—to promote desirable long-run outcomes. (shrink)

Selected-effects theories provide the most popular account of biological teleology. According to these theories, the purpose of a trait is to do whatever it was selected for. The vast majority of selected-effects theories consider biological teleology to be introduced by natural selection. We want to argue, however, that natural selection is not the only relevant selective process in biology. In particular, our proposal is that biological regulation is a form of biological selection. So, those who (...) accept selected-effects theories should recognize biological regulation as a distinctive source of biological teleology. The purposes derived from biological regulation are of special interest for explaining and predicting the behavior of organisms, given that regulatory mechanisms directly modulate the behavior of the systems they regulate. This explanatory power, added to the fact that regulation is widespread in the biological world, makes the idea that regulation gives rise to its own form of teleology a substantial contribution to the debate on biological teleology. (shrink)

In lieu of an abstract, here is a brief excerpt of the content:Philosophy, Psychiatry, & Psychology 12.4 (2005) 343-348 [Access article in PDF] Doomed by Nature: The Inevitable Failure of our Naturally Selected Functions Andreas De Block Keywords psychoanalysis, Darwinism, evolutionary psychiatry, pathogenic metaphysics In their very thoughtful and stimulating replies, the three commentators foreground several topics crucial for both psychoanalysis and philosophical psychiatry. In my short response, I focus primarily on what the commentators believe to be the paper's main (...) shortcomings. The first critique reads as follows: Freud never claimed that the Homo sapiens is a fundamentally sick animal, but in fact thought that normalcy is possible and that normal behavior need not be interpreted as neurotic, perverse or psychotic. The second is that current Darwinian psychiatry does not substantiate the view that Homo sapiens is essentially an ill animal, whatever Freud's position might be. Third and last, the proposal that all human beings are ill to the core seems to be more of a religious slogan than a scientifically useful description. What Freud Really Said A transhistorical approach to Freud's work is far from simple, considering that it spans a period of over forty years and that it underwent considerable changes during that time. Not only did Freud introduce some radically new concepts during that time, such as narcissism and the death drive. Also, he regularly changed his position on the aim of psychoanalytic therapy, the ontogenesis of anxiety, and the nature of human sexuality. That Freud sometimes saw homosexuality as an inborn drive did not keep him on other occasions from thinking that homosexual desire was a result of the repression or projection of an oedipal (heterosexual) drive. Examples like these show that any exegesis of Freud's writings inevitably has to deal with some tensions. Freud's work contains numerous apparent, as well as real, contradictions, so that it is no surprise at all that Katherine Morris can produce textual evidence "proving" that Freud never held the view I attribute to him. According to her, Freud thought that we are not all neurotics and that normalcy is possible.I do not deny that several passages in Freud's work underscore the possibility of non-neurotic normalcy. Indeed, Freudian theory even describes processes—sublimation, the transformation from Id to Ego, the resolution of the oedipal complex, among others—that explain how human beings can escape neurosis and other mental disorders. But Freud's illustrations of these mechanisms or processes make clear that he could not conceive [End Page 343] of a nonpathogenic psychodynamics. Consider, for instance, how Freud emphasizes throughout his study of Leonardo da Vinci that Leonardo's sublimations make him extremely vulnerable to psychic exhaustion or "neurasthenia" (1910). Freud never tires of repeating that there is only a gradual difference between a neurotic patient and Leonardo da Vinci, the sublimating ("healthy") artist and scientist.Morris (2005) is right, of course, in arguing that a gradual difference between normality and mental illness does not imply that there is no difference at all. Quantity should not be thought the opposite of quality, because small quantitative differences can transform an "articulation" into a "breach." To use Hegel's famous example, there is a continuum between 110° C and -10° C, but everybody knows that that water evaporates above 100° C and freezes below 0° C. Applied to mental disorders, quantitative differences in levels of testosterone and serotonin may lead to qualitative differences in behavior; in other words, categorical and dimensional approaches to mental illnesses are not mutually exclusive. Having established that, we now need to take a closer look at how Freud articulated the differences between seemingly normal individuals and the mentally ill.Freud held that neurosis, psychosis, and perversion are caused by the interplay between instincts and defense mechanisms. Further, he thought that the pathogenic instincts were almost exclusively sexual. Now, although it is true that he sometimes recognized that the fear of death and the death drive are important factors for psychic life (Deeley 2005) and for the etiology of psychosis, more often than not he interpreted the fear of death as a symbolization of... (shrink)

Is the adaptive complexity of living organisms the result of evolutionary processes alone? or does it give evidence of intentional design? Michael Ruse appears to argue that we can have it either way. As a scientist I find the argument from design unnecessary. Yet it has great appeal to humans, whose behavior is largely intentional and who look for patterns in events and for the intentions that may have produced them.

We treat meaning as nonphysical connection and potential organization. Meaning is a resource that can be used by animals to improve survival and reproduction. The evolu­tion of brains to exploit meaning occurred in two heuristic steps. First, solitary brains developed mental representations of patterns for learning and guiding adaptive action. Second, humankind greatly expanded the usefulness of meaning by using it collectively, such as by deliberately communicating information, creating a body of shared beliefs and understandings, and using meaning to organize (...) social life. The intentional application of meaning to life, as in the quest for a meaningful life, is a later development linked to ways of organizing behavior to maximize future outcomes and relate the individual to societal systems. (shrink)

This article takes an evolutionary “reverse engineering” standpoint on Homo discens, learning man, to track down the mechanisms that played a pivotal role in the natural selection of human being. The approach is “evolutionary sociological”—as opposed to gene-centred or psychologising—and utilises notions of co-evolutionary organism–environment transactions and niche construction. These are compatible with a Deweyan theory of action, which entails that in action one cannot but learn and one can only learn in action. Special attention is paid to (...) apprentice-like learning-by-doing peculiar to human socio-cultural niches since the Pleistocene, which has permitted each subsequent generation to learn the many habits and skills needed in utilising the affordances of action that constitute their ecological niche. Affordances and actions have changed over the history of human–environment transactions, but the core mechanisms of human learning have not changed much. It is increasingly important to appreciate these mechanisms now in the global age “knowledge society,” which is in a way similar to the Pleistocene era: characterised by uncertainty and life-determining problem-situations without any ready-made solutions, it calls for capacities to adapt to changing circumstances, and thus apprentice-like learning in action supported by savvy epistemological engineering of learning environments. (shrink)

Population-level theories of evolution—the stock and trade of population genetics—are statistical theories par excellence. But what accounts for the statistical character of population-level phenomena? One view is that the population-level statistics are a product of, are generated by, probabilities that attach to the individuals in the population. On this conception, population-level phenomena are explained by individual-level probabilities and their population-level combinations. Another view, which arguably goes back to Fisher but has been defended recently, is that the population-level statistics are sui (...) generis, that they somehow emerge from the underlying deterministic behavior of the individuals composing the population. Walsh et al. label this the statistical interpretation. We are not willing to give them that term, since everyone will admit that the population-level theories of evolution are statistical, so we will call this the emergentist statistical interpretation. Our goals are to show that: This interpretation is based on gross factual errors concerning the practice of evolutionary biology, concerning both what is done and what can be done; its adoption would entail giving up on most of the explanatory and predictive projects of evolutionary biology; and finally a rival interpretation, which we will label the propensity statistical interpretation succeeds exactly where the emergentist interpretation fails. (shrink)

In 1975, the English evolutionist William Donald Hamilton held in Brazil a series of lectures entitled “Population genetics and social behaviour”. The unpublished notes of these conferences—written by Hamilton and recently discovered at the British Library—offer an opportunity to reflect on some of the author’s ideas about evolution. The year of the conference is particularly significant, as it took place shortly after the applications of the Price equation with which Hamilton was able to build a model that included several levels (...) of selection. In this paper I mainly analyse the inaugural lecture in which Hamilton proposes a simple model to disprove the hypothesis supported by the British zoologist C. Vero Wynne-Edwards regarding mechanisms to prevent “over-exploitation of the food supply” in “the interests of the survival of the group”. The document presented here is of great historical interest. Not only because manuscript offers a model that—since it was intended for teaching purposes—had never before appeared in the published version, but also because of the general index of the lectures that accompanies it. The latter allows us to make some hypothetical considerations on the relationship and differences between kin-selection, group-selection and inclusive fitness that Hamilton wanted to present to the attentive, well-prepared audience of the foreign university that had invited him. (shrink)

The role of behaviour in biological evolution is examined within the context of Darwinism. All Darwinian models are based on the distinction of two mechanisms: one that permits faithful transmission of a feature from one generation to another, and another that differentially regulates the degree of this transmission. Behaviour plays a minimal role as an agent of transmission in the greater part of the animal kingdom; by contrast, the forms it may assume strongly influence the mechanisms of selection regulating (...) the different rates of transmission. We consider the decisive feature of the human species to be the existence of a phenotypical system of cultural coding characterized by precision and reliability which are the distinctive features of genetic coding in animals. We examine the consequences for the application of the Darwinian model to human history. (shrink)

Although all natural languages are spoken, there is no accepted account of the evolution of a skill prerequisite to language—control of the movements of speech. If selection applied at sexual maturity, individuals achieving some command of articulate vocal behavior in previous stages would have enjoyed unusual advantages in adulthood. I offer a parental selection hypothesis, according to which hominin parents apportioned care, in part, on the basis of their infants’ vocal behavior. Specifically, it is suggested that persistent (...) or noxious crying reduced care to individuals who would have had difficulty learning complex behaviors, and that cooing and babbling increased social interaction and care as well as control over complex oralmotor activity of the sort required by spoken language. Several different tests of the hypothesis are suggested. (shrink)

Many evolutionary models assume that behaviors are caused directly by genes. An implication is that behavioral uniformity should be found only in groups that are genetically uniform. Yet, the members of human social groups often behave in a uniform fashion, despite the fact that they are genetically diverse. Behavioral uniformity can occur through a variety of psychological mechanisms and social processes, such as imitation, consensus decision making, or the imposition of social norms. We present a series of models in which (...) genes code for social transmission rules, which in turn govern the behaviors that are adopted. Transmission rules can evolve in randomly formed groups that concentrate phenotypic variation at the between-group level, favoring the evolution of altruistic behaviors and other group-advantageous traits. In addition, a direct bias toward adopting altruistic behaviors can evolve. Our models begin to show how group selection can be a strong force in human evolution, despite the absence of extreme genetic variation among groups. (shrink)

The combinatory restriction known in linguistics as ‘selection restrictions’ are generally assumed to be a kind of linguistic structures, either syntactic or semantic, or at best cognitive structures. The idea discussed in this paper is that selection restrictions, although relevant for the description of complex meanings of linguistic expressions, do not belong to the structure of either language or cognition in any reasonable sense. Instead, they are criteria for conceptual consistency. They form a layer of shared presuppositions that (...) lie at the grounds of consistent human behaviour and therefore of consistent thought and expression and belong to a natural ontology shared far beyond the boundaries of a given linguistic community. (shrink)

Human behavior is the joint product of (i) contingencies of survival responsible for natural selection, and (ii) contingencies of reinforcement responsible for the repertoires of individuals, including (iii) the special contingencies maintained by an evolved social environment. Selection by consequences is a causal mode found only in living things, or in machines made by living things. It was first recognized in natural selection: Reproduction, a first consequence, led to the evolution of cells, organs, and organisms (...) reproducing themselves under increasingly diverse conditions. The behavior functioned well, however, only under conditions similar to those under which it was selected.Reproduction under a wider range of consequences became possible with the evolution of processes through which organisms acquired behavior appropriate to novel environments. One of these, operant conditioning, is a second kind of selection by consequences: New responses could be strengthened by events which followed them. When the selecting consequences are the same, operant conditioning and natural selection work together redundantly. But because a species which quickly acquires behavior appropriate to an environment has less need for an innate repertoire, operant conditioning could replace as well as supplement the natural selection of behavior.Social behavior is within easy range of natural selection, because other members are one of the most stable features of the environment of a species. The human species presumably became more social when its vocal musculature came under operant control. Verbal behavior greatly increased the importance of a third kind of selection by consequences, the evolution of social environments or cultures. The effect on the group, and not the reinforcing consequences for individual members, is responsible for the evolution of culture. (shrink)

Hull et al.'s analysis of operant behavior in terms of interaction and replication does not seem consistent with a genuine selection model. The putative replicators do not replicate, and the overall process is more reminiscent of directed mutation than of natural selection. General analogies between natural selection and operant reinforcement are too superficial to be of much scientific use.

Many analogies exist between the process of evolution by natural selection and of learning by reinforcement and punishment. A full extension of the evolutionary analogy to learning to include analogues of the fitness, genotype, development, environmental influences, and phenotype concepts makes possible a single theory of the learning process able to encompass all of the elementary procedures known to yield learning.

Natural selection is the populational process whereby, for instance, the relative number of a variant better suited to a given environment’s attributes increases over generations. In other words, a population’s makeup is altered, over generations, to suit the requirements of a particular environment. Niche construction is the process whereby an environment’s attributes can be stably modified by organisms, over generations, to suit requirements of those organisms. Should the latter process, when it occurs, be considered as significant for the (...) complementary fit between organism and environment as the former? According to mainstream evolutionary theory, random genetic mutation is the only source of novel, unlearned, trans-generationally persistent behavior. A growing number of biologists and philosophers of science, however, maintain that organisms are capable of generating such behavior, in response to, for instance, trans-generationally persistent environmental change, by way of phenotype-mediated, developmentally plastic mechanisms that do not require mutation. Should mechanisms of this sort be more generally recognized as the source of the selectable variation that selection operates on? Niche construction theory answers “yes” to both these questions, and the result is a debate over the comprehensiveness of mainstream evolutionary theory. (shrink)

In late September 1838, Darwin read Malthus's Essay on Population, which left him with “a theory by which to work.”115 Yet he waited some twenty years to publish his discovery in the Origin of Species. Those interested in the fine grain of Darwin's development have been curious about this delay. One recent explanation has his hand stayed by fear of reaction to the materialist implications of linking man with animals. “Darwin sensed,” according to Howard Gruber, “that some would object to (...) seeing rudiments of human mentality in animals, while others would recoil at the idea of remnants of animality in man.”116 With this link closed, Darwin hung the materialist chain around his own neck, where it rested most uncomfortably. Stephen Gould, supporting Gruber's argument, finds evidence for this reconstruction in Darwin's M and N notebooks, whichinclude many statements showing that he espoused but feared to expose something he perceived as far more heretical than evolution itself: philosophical materialism-the postulate that matter is the stuff of all existence and that all mental and spiritual phenomena are its by-products. No notion could be more upsetting to the deepest traditions of Western thought than the statement that mind-however complex and powerful-is simply a product of brain.117The proferred hypothesis suggests, then, that Darwin was acutely sensible of the social consequences of equating men with animals and therefore mind with brian, and that he thus shied from publically revealing his views until the intellectual climate became more tolerant.The history I have examined makes this hypothesis implausible. Even if Darwin warily explored the implications of his emerging theory in his notebooks, his subsequent study of Fleming, Wells, Brougham, and Kirby should have quieted any trepidation. If these natural theologians did not flinch at seeing human reason prefigured in the mind of a worm, should Darwin have? Moreover, he recognized in his M notebook that the thesis of evolutionary continuity between men and animals did not require an explicit avowal of his conviction that brain was the agent of thought.118 And in any case, his materialism was of a rather benign sort; at least he so expressed it in an annotation in Abercrombie's Inquiries concerning the Intellectual Powers (1838): “By materialism I mean, merely the intimate connection of thought with form of brain — like kind of attraction with nature of element.”119 This belief would have held little terror for British intellectuals, who were quite familiar — some even comfortable-with Locke's anti-Cartesian argument that there was nothing contradictory in supposing God could make matter to think.120 Finally, even if the intellectual atmosphere of early nineteenth-century Britain were inhospitable to Darwin's brand of materialism, there is little reason to believe he breathed a different air at mid-century while preparing his manuscript.That Darwin should not have feared suspicions of materialism, of course, does not mean that he did not. But I think there were other, more persistent sources of anxiety that kept him from rushing to publish: namely, the several conceptual obstacles he had to overcome if his theory of evolution by natural selection were to be made scientifically acceptable. Prominent among these were the problems surrounding his changing notions of instinct.The inertia of his older ideas about instinct at first made it hard for Darwin to gauge how far the theory of natural selection might be applied to behavior. By the early 1840s he finally felt ready to meet the challenge of the natural theologians by providing a naturalistic explanation for the wonderful instincts of animals. In his “Essays” of 1842 and 1844 one sort of instinct is, however, not considered-that of neuter insects. Yet Darwin seems to have appreciated the difficulties such instincts entailed at least by 1843, when he read Kirby and Spence. He simply required time to work out a solution to a problem he initially perceived as “fatal to my whole theory.” Even while writing the “Species Book” in the summer of 1857, he was still juggling several possible solutions compatible with natural selection. It was only a short time before he actually turned to work on the Origin of Species that he appears to have settled on a single explanation for the difficulties posed by the instincts of worker bees and ants. The force of his theory of community selection snapped the last critical support of the creationist hypothesis and, conveniently enough, also fractured the generalized Lamarckian account of the evolution of behavior. These results were worth waiting for. (shrink)

As the principle of natural selection is generalized to explain (adaptive) patterns of human behavior, it becomes less clear what the selective environment empirically refers to. While the environment and individual are relatively separable in the non-human biological context, they are highly entangled in the context of moral, social, and institutional evolution. This chapter brings attention to the problem of generalizing the selective environment, and argues that it is ontologically disunified and definable only through its explanatory function. What (...) unifies the selective environment is that it explains adaptation in a non-agential way, by screening off various forms of agency, whether divine, organismic, or human. This explanatory function of the selective environment helps avoid some sources of confusion when the theory of natural selection is applied to humanities and social sciences. (shrink)

Darwin hypothesized that some animals, when selecting sexual partners, possess a genuine “sense of beauty” that cannot be accounted for by the logic of natural selection. This hypothesis has been notoriously controversial. In this chapter I propose that the concept of agency can be useful to operationalize the “sense of beauty”, and can help identify the conditions under which one can infer that animals are acting as (aesthetic) agents. Focusing on a case study of the behavior of the (...) Pavo cristatus, I identify the types of evidence that would allow for the inference of agency through aesthetic choice. (shrink)

Natural selection is often envisaged as the ultimate cause of the apparent rationality exhibited by organisms in their specific habitat. Given the equivalence between selection and rationality as maximizing processes, one would indeed expect organisms to implement rational decision-makers. Yet, many violations of the clauses of rationality have been witnessed in various species such as starlings, hummingbirds, amoebas and honeybees. This paper attempts to interpret such discrepancies between economic rationality and biological rationality. After having distinguished two kinds (...) of rationality we introduce irrationality as a negation of economic rationality by biologically rational decision-makers. Focusing mainly on those instances of irrationalities that can be understood as exhibiting inconsistency in making choices, i.e. as non-conformity of a given behaviour to axioms such as transitivity or independence of irrelevant alternatives, we propose two possible families of Darwinian explanations that may account for these apparent irrationalities. First, we consider cases where natural selection may have been an indirect cause of irrationality. Second, we consider putative cases where violations of rationality axioms may have been directly favored by natural selection. Though the latter cases seem to clearly contradict our intuitive representation of natural selection as a process that maximizes fitness, we argue that they are actually unproblematic; for often, they can be redescribed as cases where no rationality axiom is violated, or as situations where no adaptive solution exists in the first place. (shrink)

In both biology and the human sciences, social groups are sometimes treated as adaptive units whose organization cannot be reduced to individual interactions. This group-level view is opposed by a more individualistic one that treats social organization as a byproduct of self-interest. According to biologists, group-level adaptations can evolve only by a process of natural selection at the group level. Most biologists rejected group selection as an important evolutionary force during the 1960s and 1970s but a positive (...) literature began to grow during the 1970s and is rapidly expanding today. We review this recent literature and its implications for human evolutionary biology. We show that the rejection of group selection was based on a misplaced emphasis on genes as “replicators” which is in fact irrelevant to the question of whether groups can be like individuals in their functional organization. The fundamental question is whether social groups and other higher-level entities can be “vehicles” of selection. When this elementary fact is recognized, group selection emerges as an important force in nature and what seem to be competing theories, such as kin selection and reciprocity, reappear as special cases of group selection. The result is a unified theory of natural selection that operates on a nested hierarchy of units.The vehicle-based theory makes it clear that group selection is an important force to consider in human evolution. Humans can facultatively span the full range from self-interested individuals to “organs” of group-level “organisms.” Human behavior not only reflects the balance between levels of selection but it can also alter the balance through the construction of social structures that have the effect of reducing fitness differences within groups, concentrating natural selection (and functional organization) at the group level. These social structures and the cognitive abilities that produce them allow group selection to be important even among large groups of unrelated individuals. (shrink)

In this paper, I argue for two main hypotheses. First, that self-control is not a natural mental kind and, second, that there is no dedicated mechanism of self-control. By the first claim, I simply mean that those behaviors we label as “self-controlled” are a somewhat arbitrarily selected hodgepodge that do not have anything in common that distinguishes them from other behaviors. In other words, self-control is a gerrymandered property that does not correspond to a natural mental or psychological (...) kind. By the second claim, I mean that self-controlled behaviors are not produced by a mechanism that is not utilized in the production of other behaviors. Not only is there no natural mental property of self-control, there is no mechanism that is dedicated to producing self-controlled behavior. I further evaluate whether this account of self-control has enough explanatory power to account for a range of phenomena related to self-control. I argue that my account does a better job of explaining these phenomena than accounts which appeal to a dedicated self-control mechanism. (shrink)

Natural selection is commonly interpreted as the fundamental mechanism of evolution. Questions about how selection theory can claim to be the all-sufficient explanation of evolution often go unanswered by today's neo-Darwinists, perhaps for fear that any criticism of the evolutionary paradigm will encourage creationists and proponents of intelligent design.In Biological Emergences, Robert Reid argues that natural selection is not the cause of evolution. He writes that the causes of variations, which he refers to as (...) class='Hi'>natural experiments, are independent of natural selection; indeed, he suggests, natural selection may get in the way of evolution. Reid proposes an alternative theory to explain how emergent novelties are generated and under what conditions they can overcome the resistance of natural selection. He suggests that what causes innovative variation causes evolution, and that these phenomena are environmental as well as organismal.After an extended critique of selectionism, Reid constructs an emergence theory of evolution, first examining the evidence in three causal arenas of emergent evolution: symbiosis/association, evolutionary physiology/behavior, and developmental evolution. Based on this evidence of causation, he proposes some working hypotheses, examining mechanisms and processes common to all three arenas, and arrives at a theoretical framework that accounts for generative mechanisms and emergent qualities. Without selectionism, Reid argues, evolutionary innovation can more easily be integrated into a general thesis. Finally, Reid proposes a biological synthesis of rapid emergent evolutionary phases and the prolonged, dynamically stable, non-evolutionary phases imposed by natural selection. (shrink)

This paper examines the history of animal behavior studies after the synthesis period. Three episodes are considered: the adoption of the theory of natural selection, the mathematization of ideas, and the spread of molecular methods in behavior studies. In these three episodes, students of behavior adopted practices and standards developed in population ecology and population genetics. While they borrowed tools and methods from these fields, they made distinct uses that set them relatively apart and led them to contribute, (...) in their own way, to evolutionary theory. These episodes also highlight some limitations of “conjunction narratives” centered on the relation between a discipline and the modern synthesis. A trend in conjunction narratives is to interpret any development related to evolution in a discipline as an “extension,” an “integration,” or as a “delayed” synthesis. I here suggest that this can lead to underestimate discontinuities in the history of evolutionary biology. (shrink)

When we think of theories that attempt to root capitalism in nature, the one that comes most readily to mind is Social Darwinism. In this theory, nature - driven by Darwinian natural selection (the struggle for existence and the survival of the fittest) - is interpreted to imply, when applied to human activities, that extreme competition will allow the most "fit" competitors to rise to the top and to survive in this "struggle for existence," and this process of (...) dog-eat-dog competition leads to both material and social progress. Not only has this theory been shown to be seriously flawed, the putative social implications of Darwinian natural selection do not accord with the findings of contemporary neoDarwinists who maintain, for example, that the behavior of monkeys and apes reveals a blend of competition and cooperation and, generally, a close connection to human moral behavior. Adam Smith provides a more helpful view of the connection between nature and capitalism. He maintains that nature's wisdom, as seen in its harmony and balance, is displayed in economics and human nature. Competitive free enterprise, as a vehicle for exchange, functions within a cooperative context and exhibits virtues and values such as mutual help and benefit, trust, harmony, and friendship. I shall show that neoDarwinists agree with Smith's view that nature supports a connection between competition and cooperation, and they maintain that moral activity, rather than destructive dog-eat-dog competition, is necessary to achieve the goals of natural selection. (shrink)

The generic account of selection proposed by Hull et al. readily fits operant learning where, by comparison with natural selection, the process is well understood but little is known about the mechanism. Objections within psychology, that operant learning ignores internal processes, fail to recognise the general significance of behaviour-environment interactions. Variation within operant response classes requires further investigation.

In both biology and the human sciences, social groups are sometimes treated as adaptive units whose organization cannot be reduced to individual interactions. This group-level view is opposed by a more individualistic one that treats social organization as a byproduct of self-interest. According to biologists, group-level adaptations can evolve only by a process of natural selection at the group level. Most biologists rejected group selection as an important evolutionary force during the 1960s and 1970s but a positive (...) literature began to grow during the 1970s and is rapidly expanding today. We review this recent literature and its implications for human evolutionary biology. We show that the rejection of group selection was based on a misplaced emphasis on genes as "replicators" which is in fact irrelevant to the question of whether groups can be like individuals in their functional organization. The fundamental question is whether social groups and other higher-level entities can be "vehicles" of selection. When this elementary fact is recognized, group selection emerges as an important force in nature and what seem to be competing theories, such as kin selection and reciprocity, reappear as special cases of group selection. The result is a unified theory of natural selection that operates on a nested hierarchy of units. The vehicle-based theory makes it clear that group selection is an important force to consider in human evolution. Humans can facultatively span the full range from self-interested individuals to "organs" of group-level "organisms." Human behavior not only reflects the balance between levels of selection but it can also alter the balance through the construction of social structures that have the effect of reducing fitness differences within groups, concentrating natural selection (and functional organization) at the group level. These social structures and the cognitive abilities that produce them allow group selection to be important even among large groups of unrelated individuals. (shrink)

This commentary is an attempt to sharpen some of the issues raised in the paper and thereby increase the generality of the proposal. Some implications of an exact definition of behavior for strategies of measurement and hence behavioral variability are discussed. The role of both respondent and operant behavior in natural selection is emphasized.

We critically examine a number of aspects of Grafen’s ‘formal Darwinism’ project. We argue that Grafen’s ‘selection-optimality’ links do not quite succeed in vindicating the working assumption made by behavioural ecologists and others—that selection will lead organisms to exhibit adaptive behaviour—since these links hold true even in the presence of strong genetic and developmental constraints. However we suggest that the selection-optimality links can profitably be viewed as constituting an axiomatic theory of fitness. Finally, we compare Grafen’s project (...) with Fisher’s ‘fundamental theorem of natural selection’, and we speculate about whether Grafen’s results can be extended to a game-theoretic setting. (shrink)

Computational functionalism [5] fails to understand the embodied and situated nature of behaviour by taking steady state functions as theoretical primitives, and by interpreting cognitive behaviour from a language-like, observer dependant framework without a naturalized normativity. Evolutionary functionalism [28, 27], on the other hand, by grounding functional normativity on historical processes fails to give an account of normative functionality based on the present causal mechanism producing behaviour. We propose an alternative autonomous dynamical framework where functionality is defined as contribution to (...) self-maintenance [15, 10, 35] and normativity as satisfaction of closure criteria. We develop this framework by a set of formal definitions in the framework of dynamical system theory and propose the hypothesis of an homeostatic-plasticity [31, 40] based general purpose value system as an internalized normative mechanism that selects between internal state trajectories to produce adaptive functionality under different environmental conditions. To test the hypothesis we develop a simulation model where lower level specifications of a control arquitecture (an homeostatic plastic DRNN) give rise (through a simulated evolutionary process) to adaptive behaviour in a foraging task where food sources can be poisonous or profitable. Analysis of the evolved agent show that plastic changes occur when the agent produces salient adaptive interactions, those plastic changes determining the adaptive strategy. The embodied and interactive adaptive functionality is dynamically analysed, illustrating the autonomous dynamical framework. (shrink)

This paper discusses the relations between three forms of altruism: behavioural, evolutionary and motivational. Altruism in a behavioural sense is an act that benefits another person. It can range from volunteering to a charity and helping a neighbour, to giving money to a non-profit organisation or donating blood. People often dedicate their material and nonmaterial resources for the benefit of others to gain psychological, social and material benefits for themselves. Thus, their altruistic acts are driven by egoistic motivation. Also, the (...) final goal of an altruistic act may be the increase in the welfare of a group or adherence to a certain moral principle or a social norm. However, at least sometimes, the welfare of others is the ultimate goal of our actions, when our altruistic acts are performed from altruistic motivation. In evolutionary sense, altruism means the sacrifice of reproductive success for the benefit of other organisms. According to evolutionary theories, behaviour which promotes the reproductive success of the receiver at the cost of the actor is favoured by natural selection, because it is either beneficial for the altruist in the long run, or for his genes, or for the group he belongs to. However, altruism among people emerges as a distinctly human combination of innate and learned behaviours. Not only do we benefit the members of our own group, but we are capable of transcending our tribalistic instincts and putting the benefit of strangers at our own personal expense as our ultimate goal. (shrink)

Using criteria of relative plausibility, it is possible to make a case for significant group selection over the 100,000 years that Anatomically Modern Humans have been both moral and egalitarian. Our nomadic forebears surely lived in egalitarian communities that levelled social differences and moralistically curbed free-riding behaviour, and this egalitarian syndrome would have had profound effects on levels of selection. First, it reduced phenotypic variation at the within-group level. Second, it increased phenotypic variation at the between-group level. Third, (...) and crucially, moral sanctioning also permitted groups to sharply curtail free-riding tendencies at the level of phenotype. The result was group selection strong enough to support altruistic genes, and a human nature that was set up for social ambivalence: that nature was mainly selfish and strongly nepotistic, but it was at least modestly and socially significantly altruistic. The effects on human social and moral life were pervasive, both in hunting bands and in more recent manifestations of human society. (shrink)

I begin this article with an increasingly accepted claim: that emotions lend differential weight to states of affairs, helping us conceptually carve the world and make rational decisions. I then develop a more controversial assertion: that environments have non-subjective emotional qualities, which organize behavior and help us make sense of the world. I defend this from ecological and related embodied standpoints that take properties to be interrelational outcomes. I also build on conceptions of experience as a cultural phenomenon, one that (...) coheres around shared environmental contours and public emotional concerns, introducing normative constraints (or what might be called “world grammars”). Endorsing this outlook suggests an argument for the view that cultural spaces have affectively charged, non-subjective, normative openings and closures. These openings and closures engender selectively permeable barriers which cordon space without physically preventing entry, as seen with decorative half walls and elevation changes. An area with such barriers may look emotionally hostile to, say, the dispirited homeless who are in fact less welcome there. Outcomes like these might be thought of as “political affordances.” These affordances can be regarded as normative openings and closures that implicitly filter, and hence segregate, according to various social divisions. Although registering political affordances requires more than the detection of ambient arrays, the notion retains core Gibsonian ideas: that affordances are values, that these values are linked with how a space can be used, and that the existence and nature of such affordances is not a subjective matter. (shrink)

In the first part of this paper, I try to clear the ground from frequent misconceptions about the relationship between fact and value by examining some uses of the adjective “natural” in ethical controversies. Such uses bear evidence to our “natural” tendency to regard nature (considered in a descriptive sense, as the complex of physical and biological regularities) as the source of ethical norms. I then try to account for the origin of this tendency by offering three related (...) explanations, the most important of which regards it as the outcome of an adaptation: if any behaviour that favours our equilibrium with the environment is potentially adaptive, nothing can be more effective for this goal than developing an attitude toward the natural world that regards it as a dispenser of sacred norms that must be invariably respected. By referring to the Aristotelian notion of human flourishing illustrated in the first part of the paper, in the second I discuss some ethical problems raised by mini-chips implantable under in our bodies. I conclude by defending the potential beneficial effects of such new technological instruments. (shrink)

This root-and-branch reevaluation of Darwin's concept of sexual selection tackles the subject from historical, epistemological and theoretical perspectives. Contributions from a wealth of disciplines have been marshaled for this volume, with key figures in behavioural ecology, philosophy, and the history of science adding to its wide-ranging relevance. Updating the reader on the debate currently live in behavioural ecology itself on the centrality of sexual selection, and with coverage of developments in the field of animal aesthetics, the book details (...) the current state of play, while other chapters trace the history of sexual selection from Darwin to today and inquire into the neurobiological bases for partner choices and the comparisons between the hedonic brain in human and non-human animals. Welcome space is given to the social aspects of sexual selection, particularly where Darwin drew distinctions between eager males and coy females and rationalized this as evolutionary strategy. Also explored are the current definition of sexual selection (as opposed to natural selection) and its importance in today's biological research, and the impending critique of the theory from the nascent field of animal aesthetics. As a comprehensive assessment of the current health, or otherwise, of Darwin's theory, 140 years after the publication of his Descent of Man, the book offers a uniquely rounded view that asks whether 'sexual selection' is in itself a progressive or reactionary notion, even as it explores its theoretical relevance in the technical biological study of the twenty-first century. (shrink)

The group selection controversy is about whether natural selection ever operates at the level of groups, rather than at the level of individual organisms. Traditionally, group selection has been invoked to explain the existence of altruistic behaviour in nature. However, most contemporary evolutionary biologists are highly sceptical of the hypothesis of group selection, which they regard as biologically implausible and not needed to explain the evolution of altruism anyway. But in their recent book, Elliot Sober (...) and David Sloan Wilson [1998] argue that the widespread opposition to group selection is founded on conceptual confusion. The theories that have been propounded as alternatives to group selection are actually group selection in disguise, they maintain. I examine their arguments for this claim, and John Maynard Smith's arguments against it. I argue that Sober and Wilson arrive at a correct position by faulty reasoning. In the final section, I examine the issue of how to apply the principle of natural selection at different levels of the biological hierarchy, which underlies the dispute between Sober and Wilson and Maynard Smith. (shrink)

In nature, gregarious animals, insects, or bacteria usually exhibit paradoxical behaviors in the form of group fission and fusion, which exerts an important influence on group’s pattern formation, information transfer, and epidemiology. However, the fission-fusion dynamics have received little attention compared to other flocking behavior. In this paper, an intermittent selective interaction based control algorithm for the self-organized fission-fusion behavior of flocking system is proposed, which bridges the gap between the two conflicting behaviors in a unified fashion. Specifically, a hybrid (...) velocity coordination strategy that includes both the egalitarian and selective interactions is proposed, where the egalitarian interaction is to maintain the flock’s order and achieve the fusion behavior while the selective interaction strategy is for the response to external stimulus information and generates the fission behavior. Numerical simulations demonstrate that the proposed control algorithm can realize the self-organized fission-fusion behavior of flocking system under a unified framework. The influences of the main control parameters on the performance of the fission-fusion behavior are also discussed. In particular, the trade-off parameterαbalances the exploration and exploitation behaviors of flocking system and significantly enhances its movement flexibility and environmental adaptivity. (shrink)

In the Origin of Species (1859), Darwin argued that his revolutionary theory of evolution by natural selection represented a significant breakthrough in the understanding of instinctive behaviour. However, many aspects in the development of his thinking on behavioural phenomena indicate that the explanation of this particular organic feature was by no means an easy one, but that it posed an authentic challenge – something that Darwin himself always recognized. This paper explores Darwin’s treatment of instincts within his theory (...) of natural selection. Particular attention is given to elucidate how he tackled the difficulties of explaining instincts as evolving mental features. He had to explain and demonstrate its inheritance, variation, and gradual accumulation within populations. The historical and philosophical aspects of his theory are highlighted, as well as his study of the case in which the explanation of instincts represented a ‘special difficulty’; that is, the sterile castes of social insects. (shrink)

Variation or rearrangement of regulatory genes is responsible for cellular malignant change. These types of chromosomal variations also produce heterochrony or paedomorphic evolution at the organismal level. Analogously, neoplasia represents a cellular macroevolutionary event, and a tumour can be said to be an evolved population of cells. To understand this cellular evolution to malignancy, it may be necessary to go beyond a clonal selection (adaptationist) explanation of neoplastic alteration. In the pericellular environment natural selection consists of the (...) organizational restraints of surrounding cells as well as the host's immunological surveillance and non-specific monocyte-macrophage systems. Indirect evidence suggests that success for the neoplasm depends not upon clonal selection, but solely upon a genetic methodology—the function of which is to elude selection.The author has coined the term cellular heterochrony to illustrate analogic similarities in the molecular modes of speciation between anaplastic cancer cells and the heterochronic evolution of organisms. By reverting to a juvenile (embryonic) repertoire of cellular behaviour a tumour secures its own tenure or niche by usurping the host's armamentarium of selection forces, employing many of the same or similar methods by which implanting and invading tissues of the mammalian embryo forestall maternal detection and rejection. A number of ways by which the tumour blocks, subverts or evades selection are discussed. (shrink)

According to kin selection theory, indirect reproductive advantages may induce individuals to care for others with whom they share genes by common descent, and the amount of care, including self-sacrifice, will increase with the proportion of genes shared. Twins represent a natural situation in which this hypothesis can be tested. Twin pairs experience the same early environment because they were born and raised at the same time and in the same family but their genetic relatedness differs depending on (...) zygosity. We compared the degree of willingness to fight and sacrifice for the co-twin among monozygotic and dizygotic pairs in a sample of 1443 same-sex and opposite-sex twins. We also analyzed the effect of the subject’s gender and that of the co-twin on those altruistic behaviors. Results partly supported the postulated explanation. MZ twins were significantly more likely than DZ twins to self-sacrifice for their co-twins, but zygosity did not affect willingness to fight for him/her. The genders of the subject and of the co-twin, not genetic relatedness, were the best predictors of aggressive altruistic intentions. (shrink)

According to kin selection theory, indirect reproductive advantages may induce individuals to care for others with whom they share genes by common descent, and the amount of care, including self-sacrifice, will increase with the proportion of genes shared. Twins represent a natural situation in which this hypothesis can be tested. Twin pairs experience the same early environment because they were born and raised at the same time and in the same family but their genetic relatedness differs depending on (...) zygosity. We compared the degree of willingness to fight and sacrifice for the co-twin among monozygotic and dizygotic pairs in a sample of 1443 same-sex and opposite-sex twins. We also analyzed the effect of the subject’s gender and that of the co-twin on those altruistic behaviors. Results partly supported the postulated explanation. MZ twins were significantly more likely than DZ twins to self-sacrifice for their co-twins, but zygosity did not affect willingness to fight for him/her. The genders of the subject and of the co-twin, not genetic relatedness, were the best predictors of aggressive altruistic intentions. (shrink)

Anderson and Rosenberg’s guidance theory of representation offers an analysis of mental content that strongly emphasises the influence that intentional states have upon the production and modulation of bodily behavior. On this view, a mental state gains both its status as a representation, and its content, in virtue of occupying a particular role in the guidance of action. I present three related challenges for the guidance theory, before defending an alternative model that is grounded not in action-guidance, but in action- (...) class='Hi'>selection. Firstly, I argue that the guidance theory fails to explain an important category of perceptual misrepresentation. Secondly, I propose that the content ascriptions predicted by the theory are not sufficiently determinate. Thirdly, I propose that the contents implicated by the guidance view do not match those that are naturally ascribed in the explanation of intentionally-directed behavior. The modified account that I develop responds to these concerns, and suggests that representational states depict affordance properties: the opportunities and obstacles that the subject’s environment offers for the pursuit of goals and plans. (shrink)