There are theoretical limitations to what can be implemented by a computer program. In this paper we are concerned with a limitation on the strength of computer implemented deduction. We use a version of the Curry paradox to arrive at this limitation.

There is significant interest in type-free systems that allow flexible self-application. Such systems are of interest in property theory, natural language semantics, the theory of truth, theoretical computer science, the theory of classes, and category theory. While there are a variety of proposed type-free systems, there is a particularly natural type-free system that we believe is prototypical: the logic of recursive algorithms. Algorithmic logic is the study of basic statements concerning algorithms and the algorithmic rules of inference between such statements. (...) As shown in [1], the threat of paradoxes, such as the Curry paradox, requires care in implementing rules of inference in this context. As in any type-free logic, some traditional rules will fail. The first part of the paper develops a rich collection of inference rules that do not lead to paradox. The second part identifies traditional rules of logic that are paradoxical in algorithmic logic, and so should be viewed with suspicion in type-free logic generally. (shrink)

We develop a functional abstraction principle for the type-free algorithmic logic introduced in our earlier work. Our approach is based on the standard combinators but is supplemented by the novel use of evaluation trees. Then we show that the abstraction principle leads to a Curry fixed point, a statement C that asserts C ⇒ A where A is any given statement. When A is false, such a C yields a paradoxical situation. As discussed in our earlier work, this situation leaves (...) one no choice but to restrict the use of a certain class of implicational rules including modus ponens. (shrink)

In this note, we consider constraints on the physical possibility of transfinite Turing machines that arise from how one models the continuous structure of space and time in one's best physical theories. We conclude by suggesting a version of Church's thesis appropriate as an upper bound for physical computation given how space and time are modeled on our current physical theories.

How do people decide what category an artifact belongs to? Previous studies have suggested that adults and, to some degree, children, categorize artifacts in accordance with the design stance, a categorization system which privileges the designer’s original intent in making categorization judgments. However, these studies have all been conducted in Western, technologically advanced societies, where artifacts are mass produced. In this study, we examined intuitions about artifact categorization among the Shuar, a hunter-horticulturalist society in the Amazon region of Ecuador. We (...) used a forced-choice method similar to previous studies, but unlike these studies, our scenarios involved artifacts that would be familiar to the Shuar. We also incorporated a community condition to examine the possible effect of community consensus on how artifacts are categorized. The same scenarios were presented to university student participants in the UK. Across populations and conditions, participants tended to categorize artifacts in terms of a creator’s intent as opposed to a differing current use. This lends support to the view that the design stance may be a universal feature of human cognition. However, we conclude with some thoughts on the limitations of the present method for studying artifact concepts. (shrink)

The Shape of Thought: How Mental Adaptations Evolve presents a road map for an evolutionary psychology of the twenty-first century. It brings together theory from biology and cognitive science to show how the brain can be composed of specialized adaptations, and yet also an organ of plasticity. Although mental adaptations have typically been seen as monolithic, hard-wired components frozen in the evolutionary past, The Shape of Thought presents a new view of mental adaptations as diverse and variable, with distinct functions (...) and evolutionary histories that shape how they develop, what information they use, and what they do with that information. The book describes how advances in evolutionary developmental biology can be applied to the brain by focusing on the design of the developmental systems that build it. Crucially, developmental systems can be plastic, designed by the process of natural selection to build adaptive phenotypes using the rich information available in our social and physical environments. This approach bridges the long-standing divide between "nativist" approaches to development, based on innateness, and "empiricist" approaches, based on learning. It shows how a view of humans as a flexible, culturally-dependent species is compatible with a complexly specialized brain, and how the nature of our flexibility can be better understood by confronting the evolved design of the organ on which that flexibility depends. (shrink)

Modularity has been the subject of intense debate in the cognitive sciences for more than 2 decades. In some cases, misunderstandings have impeded conceptual progress. Here the authors identify arguments about modularity that either have been abandoned or were never held by proponents of modular views of the mind. The authors review arguments that purport to undermine modularity, with particular attention on cognitive architecture, development, genetics, and evolution. The authors propose that modularity, cleanly defined, provides a useful framework for directing (...) research and resolving debates about individual cognitive systems and the nature of human evolved cognition. Modularity is a fundamental property of living things at every level of organization; it might prove indispensable for understanding the structure of the mind as well. (shrink)

Intent and mitigating circumstances play a central role in moral and legal assessments in large-scale industrialized societies. Al- though these features of moral assessment are widely assumed to be universal, to date, they have only been studied in a narrow range of societies. We show that there is substantial cross-cultural variation among eight traditional small-scale societies (ranging from hunter-gatherer to pastoralist to horticulturalist) and two Western societies (one urban, one rural) in the extent to which intent and mitigating circumstances influence (...) moral judgments. Although participants in all societies took such factors into account to some degree, they did so to very different extents, varying in both the types of considerations taken into account and the types of violations to which such considerations were applied. The particular patterns of assessment characteristic of large-scale industrialized societies may thus reflect relatively recently culturally evolved norms rather than inherent features of human moral judgment. (shrink)

Currently, there is widespread skepticism that higher cognitive processes, given their apparent flexibility and globality, could be carried out by specialized computational devices, or modules. This skepticism is largely due to Fodor's influential definition of modularity. From the rather flexible catalogue of possible modular features that Fodor originally proposed has emerged a widely held notion of modules as rigid, informationally encapsulated devices that accept highly local inputs and whose operations are insensitive to context. It is a mistake, however, to equate (...) such features with computational devices in general and therefore to assume, as Fodor does, that higher cognitive processes must be non‐computational. Of the many possible non‐Fodorean architectures, one is explored here that offers possible solutions to computational problems faced by conventional modular systems: an ‘enzymatic’ architecture. Enzymes are computational devices that use lock‐and‐key template matching to identify relevant information (substrates), which is then operated upon and returned to a common pool for possible processing by other devices. Highly specialized enzymes can operate together in a common pool of information that is not pre‐sorted by information type. Moreover, enzymes can use molecular ‘tags’ to regulate the operations of other devices and to change how particular substrates are construed and operated upon, allowing for highly interactive, context‐specific processing. This model shows how specialized, modular processing can occur in an open system, and suggests that skepticism about modularity may largely be due to failure to consider alternatives to the standard model. (shrink)

It is widely held that intuitive dualism—an implicit default mode of thought that takes minds to be separable from bodies and capable of independent existence—is a human universal. Among the findings taken to support universal intuitive dualism is a pattern of evidence in which “psychological” traits (knowledge, desires) are judged more likely to continue after death than bodily or “biological” traits (perceptual, physiological, and bodily states). Here, we present cross-cultural evidence from six study populations, including non-Western societies with diverse belief (...) systems, that shows that while this pattern exists, the overall pattern of responses nonetheless does not support intuitive dualism in afterlife beliefs. Most responses of most participants across all cultures tested were not dualist. While our sample is in no way intended to capture the full range of human societies and afterlife beliefs, it captures a far broader range of cultures than in any prior study, and thus puts the case for afterlife beliefs as evidence for universal intuitive dualism to a strong test. Based on these findings, we suggest that while dualist thinking is a possible mode of thought enabled by evolved human psychology, such thinking does not constitute a default mode of thought. Rather, our data support what we will call intuitive materialism—the view that the underlying intuitive systems for reasoning about minds and death produce as a default judgment that mental states cease to exist with bodily death. (shrink)

Decades of research conducted in Western, Educated, Industrialized, Rich, & Democratic (WEIRD) societies have led many scholars to conclude that the use of mental states in moral judgment is a human cognitive universal, perhaps an adaptive strategy for selecting optimal social partners from a large pool of candidates. However, recent work from a more diverse array of societies suggests there may be important variation in how much people rely on mental states, with people in some societies judging accidental harms just (...) as harshly as intentional ones. To explain this variation, we develop and test a novel cultural evolutionary theory proposing that the intensity of kin-based institutions will favor less attention to mental states when judging moral violations. First, to better illuminate the historical distribution of the use of intentions in moral judgment, we code and analyze anthropological observations from the Human Area Relations Files. This analysis shows that notions of strict liability—wherein the role for mental states is reduced—were common across diverse societies around the globe. Then, by expanding an existing vignette-based experimental dataset containing observations from 321 people in a diverse sample of 10 societies, we show that the intensity of a society's kin-based institutions can explain a substantial portion of the population-level variation in people's reliance on intentions in three different kinds of moral judgments. Together, these lines of evidence suggest that people's use of mental states has coevolved culturally to fit their local kin-based institutions. We suggest that although reliance on mental states has likely been a feature of moral judgment in human communities over historical and evolutionary time, the relational fluidity and weak kin ties of today's WEIRD societies position these populations' psychology at the extreme end of the global and historical spectrum. (shrink)

We make the case that scientifically accurate and politically feasible responses to the climate crisis require a complex understanding of human cultural practices of niche construction that moves beyond the adaptive significance of culture. We develop this thesis in two related ways. First, we argue that cumulative cultural practices of niche construction can generate stable equilibria and runaway selection processes that result in long-term existential risks within and across cultural groups. We dub this the back of the invisible hand. Second, (...) we argue that the ability of cultural groups to innovate technological solutions to environmental problems is highly constrained in ways that are exacerbated by sustained intergroup conflict, inequality and by inherently unpredictable cascades in climate change and human migration patterns. After developing these theoretical points about human cultural practices of niche construction in detail, we conclude our discussion with some tentative practical suggestions about the way that cultural evolutionary history can more fruitfully be used in efforts to remit the climate crisis and contribute to sustainable practices of human climate change adaptation. (shrink)

This essay examines the proposal that psychological essentialism results from a history of natural selection acting on human representation and inference systems. It has been argued that the features that distinguish essentialist representational systems are especially well suited for representing natural kinds. If the evolved function of essentialism is to exploit the rich inductive potential of such kinds, then it must be subserved by cognitive mechanisms that carry out at least three distinct functions: identifying these kinds in the environment, constructing (...) essentialized representations of them, and constraining inductive inferences about kinds. Moreover, there are different kinds of kinds, ranging from nonliving substances to biological taxa to within-species kinds such as sex, and the causal processes that render these categories coherent for the purposes of inductive generalization vary. If the evolved function of essentialism is to support inductive generalization under ignorance of true causes, and if kinds of kinds vary in the implicit assumptions that support valid inductive inferences about them, then we expect different, functionally incompatible modes of essentialist thinking for different kinds. In particular, there should be differences in how biological and nonbiological substances, biological taxa, and biological and social role kinds are essentialized. The functional differences between these kinds of essentialism are discussed. (shrink)

This essay examines the proposal that psychological essentialism results from a history of natural selection acting on human representation and inference systems. It has been argued that the features that distinguish essentialist representational systems are especially well suited for representing natural kinds. If the evolved function, of essentialism is to exploit the rich inductive potential of such kinds, then it must be subserved by cognitive mechanisms that carry out at least three distinct functions: identifying these kinds in the environment, constructing (...) essentialized representations of them, and constraining inductive inferences about kinds. Moreover, there are different kinds of kinds, ranging from nonliving substances to biological taxa to within-species kinds such as sex, and the causal processes that render these categories coherent for the purposes of inductive generalization vary. If the evolved function of essentialism is to support inductive generalization under ignorance of true causes, and if kinds of kinds, vary in the implicit assumptions that support valid inductive inferences about them, then we expect different, functionally incompatible modes of essentialist thinking for different kinds. In particular, there should be differences in how biological and nonbiological substances, biological taxa, and biological and social role kinds are essentialized. The functional differences between these kinds of essentialism are discussed. (shrink)

Currently, there is widespread skepticism that higher cognitive processes, given their apparent flexibility and globality, could be carried out by specialized computational devices, or modules. This skepticism is largely due to Fodor’s influential definition of modularity. From the rather flexible catalogue of possible modular features that Fodor originally proposed has emerged a widely held notion of modules as rigid, informationally encapsulated devices that accept highly local inputs and whose opera- tions are insensitive to context. It is a mistake, however, to (...) equate such features with computational devices in general and therefore to assume, as Fodor does, that higher cognitive processes must be non-computational. Of the many possible non-Fodorean architectures, one is explored here that offers possible solutions to computational problems faced by conventional modular systems: an ‘enzymatic’ architecture. Enzymes are computational devices that use lock-and-key template matching to iden- tify relevant information (substrates), which is then operated upon and returned to a common pool for possible processing by other devices. Highly specialized enzymes can operate together in a common pool of information that is not pre-sorted by information type. Moreover, enzymes can use molecular ‘tags’ to regulate the operations of other devices and to change how particular substrates are construed and operated upon, allowing for highly interactive, context-specific processing. This model shows how specialized, modular processing can occur in an open system, and suggests that skepti- cism about modularity may largely be due to failure to consider alternatives to the standard model. (shrink)

The ability to make inductive inferences is important because without it, generalization of knowledge to new circumstances would be impossible. One context in which such inductive skills are likely to have been important over evolutionary time is encounters with animals. Previous research suggests that children take into account at least two kinds of relationships between animals when making inductive inferences about them: descent relationships, and design relationships. Because descent and design relationships are sometimes orthogonal, making correct inferences about particular traits (...) sometimes requires overlooking one kind of relationship in favor of the other. In this study, I used a base-to-target induction task to examine the use of two inference rules in 5 to 12 year old Shuar children from the Amazon region of Ecuador. The descent rule uses taxonomic relationships when the function of the trait being judged is ambiguous or unknown, and the design rule privileges ecological relationships over taxonomic relationships when the function of the trait is relevant to the ecological category in question. The results show that Shuar children do employ both of these rules, and are able to switch between them for different kinds of traits, as the descent/design mode hypothesis predicts. Children in both the younger age group and the older age group were able to use these rules, but the older children showed a slightly different pattern due to the use of specific acquired knowledge about some of the taxa. (shrink)

α-recursion lifts classical recursion theory from the first transfinite ordinal ω to an arbitrary admissible ordinal α [10]. Idealized computational models for α-recursion analogous to Turing machine models for classical recursion have been proposed and studied [4] and [5] and are applicable in computational approaches to the foundations of logic and mathematics [8]. They also provide a natural setting for modeling extensions of the algorithmic logic described in [1] and [2]. On such models, an α-Turing machine can complete a θ-step (...) computation for any ordinal θ < α. Here we consider constraints on the physical realization of α-Turing machines that arise from the structure of physical spacetime. In particular, we show that an α-Turing machine is realizable in a spacetime constructed from R only if α is countable. While there are spacetimes where uncountable computations are possible and while they may even be empirically distinguishable from a standard spacetime, there is good reason to suppose that such nonstandard spacetimes are nonphysical. We conclude with a suggestion for a revision of Church’s thesis appropriate as an upper bound for physical computation. (shrink)

Beller, Bender, and Medin argue that a reconciliation between anthropology and cognitive science seems unlikely. We disagree. In our view, Beller et al.’s view of the scope of what anthropology can offer cognitive science is too narrow. In focusing on anthropology’s role in elucidating cultural particulars, they downplay the fact that anthropology can reveal both variation and universals in human cognition, and is in a unique position to do so relative to the other subfields of cognitive science. Indeed, without cross-cultural (...) research, the universality of any aspect of human cognition cannot truly be established. Therefore, if the goal of cognitive science is to understand the cognitive capacities of our species as a whole, then it cannot do without anthropology. We briefly review a growing body of anthropological work aimed at answering questions about human cognition and offer suggestions for future work. (shrink)

Evolutionary explanations of behavior are special in that they involve both proximate and ultimate components. Proximately, evolutionary accounts posit mechanisms that generate observed patterns of behavior. At the ultimate level, evolutionary accounts explain the existence of these proximate mechanisms via evolutionary processes such as selection or drift acting in the past. Does positing or accepting such explanations carry any risks? Here I consider two kinds of risk, epistemic and ethical. Epistemic risk is the risk of being wrong about a matter (...) of fact, such as whether a posited empirical pattern actually exists, or that a particular set of causes explains it. Ethical risk is the risk of causing harm. If the acceptance of a particular explanation for an observed pattern of behavior entails real-world consequences that could lead to harm, then epistemic risk entails ethical risk. Here I consider these risks in cases of evolutionary explanation, and ask whether evolutionary explanations might carry special risks that we should consider when developing and testing evolutionary hypotheses. (shrink)

In Crawford, C. & Krebs, D. (eds.) Foundations of evolutionary psychology: Ideas, issues, applications and findings. (2nd Ed.) Mahwah, NJ: Erlbaum Associates.

We agree that much of language evolution is likely to be adaptation of languages to properties of the brain. However, the attempt to rule out the existence of language-specific adaptations a priori is misguided. In particular, the claim that adaptation to cannot occur is false. Instead, the details of gene-culture coevolution in language are an empirical matter.

HIT produces category-specific deficits without category- specific mechanisms by assuming that differences in properties of objects are transparently converted into differences in representational format. A complete model would specify the mechanisms that accomplish this. Such category-specific mechanisms may have evolved because assumptions about the properties of some kinds of objects (e.g., living things) are invalid for others (e.g., artifacts).

Human moral judgement may have evolved to maximize the individual's welfare given parochial culturally constructed moral systems. If so, then moral condemnation should be more severe when transgressions are recent and local, and should be sensitive to the pronouncements of authority figures (who are often arbiters of moral norms), as the fitness pay-offs of moral disapproval will primarily derive from the ramifications of condemning actions that occur within the immediate social arena. Correspondingly, moral transgressions should be viewed as less objectionable (...) if they occur in other places or times, or if local authorities deem them acceptable. These predictions contrast markedly with those derived from prevailing non-evolutionary perspectives on moral judgement. Both classes of theories predict purportedly species-typical patterns, yet to our knowledge, no study to date has investigated moral judgement across a diverse set of societies, including a range of small-scale communities that differ substantially from large highly urbanized nations. We tested these predictions in five small-scale societies and two large-scale societies, finding substantial evidence of moral parochialism and contextual contingency in adults' moral judgements. Results reveal an overarching pattern in which moral condemnation reflects a concern with immediate local considerations, a pattern consistent with a variety of evolutionary accounts of moral judgement. (shrink)

In P. Carruthers, S. Laurence, & S. Stich (Eds.). The innate mind: Structure and content. (pp. 305-337). New York: Oxford University Press.

Recent work has suggested that conservation efforts such as restoration ecology and invasive species eradication are largely value-driven pursuits. Concurrently, changes to global climate are forcing ecologists to consider if and how collections of species will migrate, and whether or not we should be assisting such movements. Herein, we propose a philosophical framework which addresses these issues by utilizing ecological and evolutionary interrelationships to delineate individual ecological communities. Specifically, our Evolutionary Community Concept recognizes unique collections of species that interact and (...) have co-evolved in a given geographic area. We argue this concept has implications for a number of contemporary global conservation issues. Specifically, our framework allows us to establish a biological and science-driven context for making decisions regarding the restoration of systems and the removal of exotic species. The ECC also has implications for how we view shifts in species assemblages due to climate change and it advances our understanding of various ecological concepts, such as resilience. (shrink)

This work addresses corruption in politics and the public services, arguing that corrupt public officials should be exposed, prosecuted and gaoled, just like their colleagues in the private sector. It covers ethical standards in the public service, both state and federal; the practice of government; the relationships between officials; their advisors and the public; the interplay between politics and personal behaviour, and offering explanations as to what can be done about corruption in public service through asking questions like; how does (...) corruption gain a foothold in public affairs?; how can public trust be rebuilt between bureaucrats, the politicians and the people who vote for them?; and how can we improve accoutability over the cover-ups? (shrink)

David Buller's recent book, Adapting Minds, is a philosophical critique of the field of evolutionary psychology. Buller argues that evolutionary psychology is utterly bankrupt from both a theoretical and an empirical point of view. Although Adapting Minds has been well received in both the academic press and the popular media, we argue that Buller's critique of evolutionary psychology fails.

Clark and Fischer argue that humans treat social artifacts as depictions. In contrast, theories of distributed cognition suggest that there is no clear line separating artifacts from agents, and artifacts can possess agency. The difference is likely a result of cultural framing. As technology and artificial intelligence grow more sophisticated, the distinction between depiction and agency will blur.

David Buller’s recent book, _Adapting Minds_, is a philosophical critique of the field of evolutionary psychology. Buller argues that evolutionary psychology is utterly bankrupt from both a theoretical and an empirical point of view. Although _Adapting Minds _has been well received in both the academic press and the popular media, we argue that Buller’s critique of evolutionary psychology fails.

There exists substantial cultural variation in how emotions are expressed, but there is also considerable evidence for universal properties in facial and vocal affective expressions. This is the first empirical effort examining the perception of vocal emotional expressions across cultures with little common exposure to sources of emotion stimuli, such as mass media. Shuar hunter-horticulturalists from Amazonian Ecuador were able to reliably identify happy, angry, fearful and sad vocalizations produced by American native English speakers by matching emotional spoken utterances to (...) emotional expressions portrayed in pictured faces. The Shuar performed similarly to English speakers who heard the same utterances in a content-filtered condition. These data support the hypothesis that vocal emotional expressions of basic affective categories manifest themselves in similar ways across quite disparate cultures. (shrink)

Humans are an exceptionally cooperative species, but there is substantial variation in the extent of cooperation across societies. Understanding the sources of this variability may provide insights about the forces that sustain cooperation. We examined the ontogeny of prosocial behavior by studying 326 children 3–14 y of age and 120 adults from six societies (age distributions varied across societies). These six societies span a wide range of extant human variation in culture, geography, and subsistence strategies, including foragers, herders, horticulturalists, and (...) urban dwellers across the Americas, Oceania, and Africa. When delivering benefits to others was personally costly, rates of prosocial behavior dropped across all six societies as children approached middle childhood and then rates of prosociality diverged as children tracked toward the behavior of adults in their own societies. When prosocial acts did not require personal sacrifice, prosocial responses increased steadily as children matured with little variation in behavior across societies. Our results are consistent with theories emphasizing the importance of acquired cultural norms in shaping costly forms of cooperation and creating cross-cultural diversity. (shrink)

The study of conversational humor has received relatively little empirical attention with almost no examinations of the role of vocal signals in spontaneous humor production. Here we report an analysis of spontaneous humorous speech in a rural Brazilian collective farm. The sample was collected over the course of ethnographic fieldwork in northeastern Brazil, and is drawn specifically from the monthly communal business meetings conducted in Portuguese. Our analyses focused on humorous utterances identified by the subsequent presence of laughter. Acoustic features (...) of these utterances were compared to non-humorous utterances by the same speakers of similar length and immediately preceding them to look for prosodic contrasts. This corpus provided a unique opportunity for examining the way people mark their humorous productions in a non-humorous environment. Contrary to the notion that speakers must mark their production of humor in order to facilitate audience understanding, no significant marking of a joking “frame” was detected across a range of acoustic dimensions. The only consistent difference — that the set-up and punch line segments were louder than baseline speech before it — does not well support a marking hypothesis and more likely reflects speaker adjustments to the acoustic conditions of the meeting hall. We present these data from the perspective of the encryption theory of humor that predicts speakers will not generally mark spontaneous, conversational humor in most contexts. (shrink)