Carl Brusse

In the human evolutionary sciences, there is a near-consensus that normative cognition and normative motivation are adaptations, the result of selection for psychological capacities that enable agents to harness cooperation profits more effectively, though specific versions of this idea differ markedly. This article picks up an alternative idea floated in the existing literature but not developed: norms evolved to reduce uncertainty about the social environment. While reducing uncertainty has positive effects on cooperation, by making coordination less problematic, it has positive effects on private, and even antisocial, activities as well. While the evidence is far from decisive, we suggest that it supports the uncertainty-reduction hypothesis more clearly than the normative-guidance-enhances-cooperation hypothesis: it is more consistent with the regulatory breadth of norms, the observed cultural diversity of norms, and the apparent existence of anti-cooperative norms.

The selected effects or ‘etiological’ theory of Proper function is a naturalistic and realist account of biological teleology. It is used to analyse normativity in philosophy of language, philosophy of mind, philosophy of medicine, and elsewhere. The theory has been developed with a simple and intuitive view of natural selection. Traits are selected because of their positive effects on the fitness of the organisms that have them. These ‘selected effects’ are the Proper functions of the traits. Proponents argue that this analysis of biological teleology has the unique advantage that the selected effect function of a trait is also a causal explanation of the trait: the trait exists because it performs this function. We show, however, that selected effect functions as currently defined explain the existence of traits only under highly restrictive assumptions about evolutionary dynamics. In many common scenarios in which traits evolve by natural selection, selected effect functions do not explain those traits. This is because definitions of selected effect function extract from any evolutionary scenario only the information that would be explanatorily relevant in the simple evolutionary scenario implicit in those definitions. When applied to more complex scenarios, selected effect functions omit the key information that is explanatorily relevant in those scenarios. The assumptions required for selected effect functions to be explanatory are particularly unlikely to hold in the domain that its proponents care most about—the evolution of representation. A more adequate selected effects theory of Proper functions may be possible, but will require much greater attention to the structure of actual evolutionary explanations.

This book examines why individuals and communities invest heavily in their religious life through multi-disciplinary perspectives. It pursues philosophical, psychological, deep time historical and adaptive answers to this question. Religion is a profoundly puzzling phenomenon from an evolutionary perspective. Commitment to religions are typically expensive, and most of the beliefs that motivate them cannot be true (since religious belief systems are inconsistent with one another). Yet some form of religion seems to be universal and resilient in historically known cultures – though not, if archaeology is to be trusted, in human communities early in the evolution of our species. We have collectively invented religion over about the last 100,000 years. Stemming from an interdisciplinary workshop, this book grapples with these challenges and features diverse contributions: some offer evolutionary and historical analyses, identifying hidden adaptive benefits to religion independent of the veracity of religious belief. Others see connections between religious commitment and commitment to the social norms that make cooperative life possible and explore aspects of human psychology that make religious belief tempting. Broad in scope and theoretically ambitious, Religion and Its Evolution: Signals, Norms and Secret Histories will be a key resource for scholars and researchers of religious studies, sciences of religion, psychology, anthropology, the cultural evolution of religion and the sociology of religion. This book was originally published as a special issue of Religion, Brain & Behavior.

This paper examines and contrasts two closely related evolutionary explanations in human behaviour: signalling theory, and the theory of Credibility Enhancing Displays. Both have been proposed to explain costly, dangerous, or otherwise ‘extravagant’ social behaviours, especially in the context of religious belief and practice, and each have spawned significant lines of empirical research. However, the relationship between these two theoretical frameworks is unclear, and research which engages both of them is largely absent. In this paper we seek to address this gap at the theoretical level, examining the core differences between the two approaches and prospects and conditions for future empirical testing. We clarify the dynamical and mechanistic bases of signalling and CREDs as explanatory models and contrast the previous uses to which they have been put in the human sciences. Because of idiosyncrasies regarding those uses, several commonly supposed differences and comparative advantages are actually misleading and not in fact generalisable. We also show that signalling and CREDs theories as explanatory models are not interchangeable, because of deep structural differences. As we illustrate, the proposed causal networks of each theory are distinct, with important differences in the endogeneity of various phenomena within each model and their explanatory targets. As a result, they can be seen as complementary rather than in competition. We conclude by surveying the current state of the literature and identifying the differential predictions which could underpin more comprehensive empirical comparison in future research.

It is often taken for granted that notions of health and disease are generally applicable across the biological world, in that they are not restricted to contemporary human beings, and can be unproblematically applied to a variety of organisms both past and present. In the historical sciences it is also common to normatively contrast health states of individuals and populations from different times and places: e.g., to say that due to nutrition or pathogen load, some lived healthier lives than others. However, health concepts in contemporary philosophy of medicine have not been developed with such cross-lineage, non-human, or diachronic uses in mind, and this generates what I call the ‘new normal’ problem. I argue that the new normal problem shows that current naturalistic approaches to health are worryingly incomplete. Using examples drawn from evolutionary archaeology and the human fossil record, I outline an alternative, function-based strategy for naturalizing health that might help address the new normal problem. Interestingly, this might also reconstruct a certain uniqueness for humans in the philosophy and science of health, due to the deep history of obligate enculturation and cultural adaptation that archaeology demonstrates.

The selected effects or ‘etiological’ theory of Proper function is a naturalistic and realist account of biological teleology. It is used to analyse normativity in philosophy of language, philosophy of mind, philosophy of medicine and elsewhere. The theory has been developed with a simple and intuitive view of natural selection. Traits are selected because of their positive effects on the fitness of the organisms that have them. These ‘selected effects’ are the Proper functions of the traits. Proponents argue that this analysis of biological teleology has the unique advantage that the selected effect function of a trait is also a causal explanation of the trait: the trait exists because it performs this function. We show, however, that selected effect functions as currently defined explain the existence of traits only under highly restrictive assumptions about evolutionary dynamics. In many common scenarios in which traits evolve by natural selection, selected effect functions do not explain those traits. This is because definitions of selected effect function extract from any evolutionary scenario only the information that would be explanatorily relevant in the simple evolutionary scenario implicit in those definitions. When applied to more complex scenarios selected effect functions omit the key information that is explanatorily relevant in those scenarios. The assumptions required for selected effect functions to be explanatory are particularly unlikely to hold in the domain that its proponents care most about - the evolution of representation. A more adequate selected effects theory of Proper functions may be possible, but will require much greater attention to the structure of actual evolutionary explanations.

The signaling theory of religion has many claimed virtues, but these are not necessarily all realizable at the same time. Modeling choices involve trade-offs, and the available options here have not traditionally been well understood. This paper offers an overview of signaling theory relevant to the signaling theory of religion, arguing for a narrow, “core” reading of it. I outline a broad taxonomy of the choices on offer for signaling models, and examples of how previous and potential approaches to modeling religious signaling meet or fail to meet the initial promise of the theory. A pluralist approach to religious signaling seems possible, but this would require a high level of detail and specificity with respect to both formal models and target systems.

The origins of human social cooperation confound simple evolutionary explanation. But from Darwin and Durkheim onward, theorists (anthropologists and sociologists especially) have posited a potential link with another curious and distinctively human social trait that cries out for explanation: religion. This dissertation explores one contemporary theory of the co-evolution of religion and human social cooperation: the signalling theory of religion, or religious signalling theory (RST). According to the signalling theory, participation in social religion (and its associated rituals and sanctions) acts as an honest signal of one’s commitment to a religiously demarcated community and its way of doing things. This signal would allow prosocial individuals to positively assort with one another for mutual advantage, to the exclusion of more exploitative individuals. In effect, the theory offers a way that religion and cooperation might explain one another, but which that stays within an individualist adaptive paradigm. My approach is not to assess the empirical adequacy of the religious signalling explanation or contrast it with other explanations, but rather to deal with the theory in its own terms – isolating and fleshing out its core commitments, explanatory potential, and limitations. The key to this is acknowledging the internal complexities of signalling theory, with respect to the available models of honest signalling and the extent of their fit (or otherwise) with religion as a target system. The method is to take seriously the findings of formal modelling in animal signalling and other disciplines, and to apply these (and methods from the philosophy of biology more generally) to progressively build up a comprehensive picture of the theory, its inherent strengths and weaknesses. The first two chapters outline the dual explanatory problems that cooperation and religion present for evolutionary human science, and surveys contemporary approaches toward explaining them. Chapter three articulates an evolutionary conception of the signalling theory, and chapters four to six make the case for a series of requirements, limitations, and principles of application. Chapters seven and eight argue for the value of formal modelling to further flesh out the theory’s commitments and potential and describe some simple simulation results which make progress in this regard. Though the inquiry often problematizes the signalling theory, it also shows that it should not be dismissed outright, and that it makes predictions which are apt for empirical testing.

We consider modifications to the standard David Lewis signaling game and relax a number of unrealistic implicit assumptions that are often built into the framework. In particular, we motivate and explore various asymmetries that exist between the sender and receiver roles. We find that endowing receivers with a more realistic set of responses significantly decreases the likelihood of signaling, while allowing for unequal selection pressure often has the opposite effect. We argue that the results of this article can also help make sense of a well-known evolutionary puzzle regarding the absence of an evolutionary arms race between sender and receiver in conflict-of-interest signaling games.

The handicap principle stipulates that signal reliability can be maintained if signals are costly to produce. Yet empirical biologists are typically unable to directly measure evolutionary costs, and instead appeal to expenditure as a sensible proxy. However the link between expenditure and cost is not always as straightforward as proponents of HP assume. We consider signaling interactions where whether the expenditure associated with signaling is converted into an evolutionary cost is in some sense dependent on the behavior of the intended recipient of the signal. We illustrate this with a few empirical examples and demonstrate that on this alternative expenditure to cost mapping the traditional predictions of HP no longer hold. Instead of full information transfer, a partially informative communication system like those uncovered by Wagner :163–181, 2013) and Zollman et al. is possible.

Conceptual change can occur for a variety of reasons; some more scientifically significant than others. The 2006 definition of ‘planet’, which saw Pluto reclassified as a dwarf planet, is an example toward the more mundane end of the scale. I argue however that this case serves as a useful example of a related phenomenon, whereby what appears to be a single kind term conceals two or more distinct concepts with independent scientific utility. I examine the historical background to this case, as a template for developing additional evidence for pluralist approaches to conceptual disputes within science and elsewhere.

Cultural evolution is a growing, interdisciplinary, and disparate field of research. In ‘Cultural evolution: conceptual challenges”, Tim Lewens offers an ambitious analytical survey of this field that aims to clarify and defend its epistemic contributions, and highlight the limitations and risks associated with them. One overarching contention is that a form of population thinking dubbed the ‘kinetic approach’ should be seen as a unifying and justifying principle for cultural evolution, especially when considering the role of formal modelling. This book makes a number of extremely valuable contributions to the literature. However, I argue that not all is as it may seem regarding the kinetic approach and that, while it does little to diminish the book’s value, the use which Lewens makes for it is problematic.