Evolutionary biology is striking for its ability to explain a large and diverse range of empirical phenomena on the basis of a few general theoretical principles. This article offers a philosophical perspective on the way that evolutionary biology has come to achieve such impressive generality, by focusing on “the strategy of endogenization”. This strategy involves devising evolutionary explanations for biological features that were originally part of the background conditions, or scaffolding, against which such explanations take place. Where successful, the strategy (...) moves biology a step closer to the ideal of explaining as much as possible from evolutionary first principles. The strategy of endogenization is illustrated through a series of biological examples, historical and recent, and its philosophical implications are explored. (shrink)

La plupart des projets d’architectures cognitives dans les sciences cognitives et des explications des processus cérébraux dans les neurosciences interprètent l’esprit/cerveau comme réactif : le processus est déclenché par un stimulus et se termine par une réponse. Mais il y a de plus en plus de données laissant penser que le cerveau est endogéniquement actif : des oscillations de l’activité électrochimique à de multiples fréquences ont lieu dans le cerveau même en l’absence de stimuli et ceux-ci servent plutôt à moduler (...) ces oscillations qu’à déclencher l’activité. De plus, des données montrent que cette activité endogène est utilisée dans diverses activités de traitement de l’information. Je m’appuie sur les données issues des enregistrements cellulaires unitaires, de l’EEG et de l’IRMf en situation passive, afin de soutenir la thèse d’un comportement oscillatoire continu dans le cerveau et d’identifier plusieurs manières dont ce comportement peut contribuer à la cognition. Si les sciences cognitives ont pour but de comprendre comment nous effectuons des tâches cognitives, elles ont besoin de développer des architectures cognitives qui intègrent le type d’activité endogène dynamique présentée par le cerveau. (shrink)

Endogenous retrovirsuses (ERVs) have long been known to influence gene expression in plants in important ways, but what of their roles in mammals? Our relatively sparse knowledge in that area was recently increased with the finding that ERVs can influence the expression of mammalian resident genes by disrupting transcriptional termination. For many mammalian biologists, retrotransposition is considered unimportant except when it disrupts the reading frame of a gene, but this view continues to be challenged. It has been known for some (...) time that integration into an intron can create novel transcripts and integration upstream of a gene can alter the expression of the transcript, in many cases producing phenotypic consequences and disease. The new findings on transcriptional termination extend the opportunities for retrotransposons to play a role in human disease. (shrink)

That endogenous retrovirus (ERV) is present within the placenta of humans and other mammals has been known for the past 25 years, but the significance of this observation is still not fully understood. Much molecular biological data have emerged in recent years to support the earlier electron microscopic data on the presence of placental ERV. The evidence for ERV in animal and human placental tissue is presented, then integrated with data on the the presence of ERV in a range of (...) other tissues, in particular teratocarcinoma cells. Placental invasiveness and maternal immunosuppression are then discussed in relation to metalloproteinase secretion, the immunosuppressive potential of retroviruses, and placental growth factors, while the evidence for a functional link between placental proto‐oncogenes and trophoblast malignancy is reviewed. Finally, placental development, structure, and life span are discussed within an evolutionary context. The hypothesis that one or more ancient trophoblastic ERVs could have played a role in the evolution and divergence of all placental mammals is evaluated. BioEssays 20:307‐316, 1998. © 1998 John Wiley & Sons, Inc. (shrink)

Lowest-unique sealed-bid auctions are auctions with endogenous participation, costly bids, and the lowest bid among all unique bids wins. Properties of symmetric NEs are studied. The symmetric NE with the lowest expected gains is the maximin outcome under symmetric strategies, and it is the solution to a mathematical program. Comparative statics for the number of bidders, the value of the item and the bidding cost are derived. The two bidders’ auction is equivalent to the Hawk–Dove game. Simulations of replicator dynamics (...) provide numerical evidence that the symmetric NE with the lowest expected gains is also asymptotically stable. (shrink)

In addition to endogenously produced opiates, which are part of normal affiliative neurocircuitry and attachment formation, exogenous opiates – such as drugs of addiction and abuse – may affect affiliation. We consider possible modulatory effects of such exogenous opiates on the development of early parent–infant attachment from both parents' and infants' perspectives.

Why do people who disagree about one subject tend to disagree about other subjects as well? In this paper, we introduce a model to explore this phenomenon of ‘epistemic factionization’. Agents attempt to discover the truth about multiple propositions by testing the world and sharing evidence gathered. But agents tend to mistrust evidence shared by those who do not hold similar beliefs. This mistrust leads to the endogenous emergence of factions of agents with multiple, highly correlated, polarized beliefs.

We consider a two-player contest in which one contestant has a headstart advantage, but both can exert further effort. We allow the prize to depend on total performance in the contest and consider the respective cases in which efforts are productive and destructive of prize value. When the contest success function takes a logit form, and marginal cost is increasing in effort, we show that a Nash equilibrium exists and is unique both in productive and destructive endogenous prize contests. In (...) equilibrium, the underdog expends more resources to win the prize, but still his probability of winning remains below that of the favorite. In a productive contest, the underdog behaves more aggressively and wins the prize more often in comparison to a fixed-value contest. Thus, the degree of competitive balance—defined as the level of uncertainty of the outcome—depends upon the prize nature of the contest. (shrink)

Endogenous reward (intrinsic reward at will) is a fiat currency that is occasioned by steps toward any goals which are challenging and/or uncommon enough to prevent its debasement by inflation. A “theory of mental computational processes” should propose what properties let goals grow from appetites for endogenous rewards. Endogenous reward may be the universal selective factor in all modifiable mental processes.

In this paper, we analyse the simplest possible three-dimensional model of endogenous growth to account for the relationship between financial intermediation and economic growth. In our setting, households maximize an interim utility function and firms maximize profit. Households can save money only through banks which offer firms investment loans. We show that under very general assumptions, investments realized by firms depend not only on savings accumulated by banks but also on financial intermediation technology ϕ(θ). Using mathematical methods of dynamical systems, (...) we found stationary states of the system and study their stability. (shrink)

This paper develops a mechanistic account of basic mental agency by identifying similarities between two of its major exemplars: endogenous attention and imagination. Five key similarities are identified: i) that both capacities are driven by currently prioritised goals that are either person-level or apt to become person-level. ii) that both deliver their outputs to the working memory iii) that both range across all and only conceptual contents; iv) that both proceed under the guidance of norms and/or habits; and v) that (...) both directly activate rather than inhibit content. These five features are consolidated by proposing that basic mental agency is essentially the power to call for conceptual content and hold it within our working memories. (shrink)

This paper examines the theoretical background and actual behavior in a gaming tournament with endogenous timing where a person has more incentive, structure, and time to form a strategy. The baseline treatment suggests that subgame perfection is a reasonable predictor of behavior –- subjects made 170 of 208 theoretically predicted choices of best actions, with the majority of mistakes made in timing choices by the players who did not survive the cut to the second round. Four sensitivity treatments established that (...) the design feature that lead to more predictable behavior was time to think –- 745 of 960 correctly predicted decisions with more time versus 595 of 960 with less time. A random effects Probit model suggests that the key design feature that closed the gap between predicted and observed behavior was not necessarily the non-linear payoffs created by the tournament design, but rather that the key was providing people with more time to think about their strategy. (shrink)

The goal of this study is to characterize observers’ abilities to discriminate between endogenous and exogenous changes. To do so, we developed a new experimental paradigm. On each trial, participants were shown a dot pattern on the screen. Next, the pattern disappeared and participants were to reproduce it. Changes were surreptuously introduced in the stimulus, either by presenting participants anew with the dot pattern they had themselves produced on the previous trial or by presenting participants with a slightly different dot (...) pattern . We analyzed awareness of the changes and behavioral adaptation to them in a dynamical manner. We observe signal attenuation in the presence of endogenous change, dissociation between self-attribution reports and behavioral effect of agency. We discuss the source of this sensitive attenuation as well as the relation between a minimal or core self and an extended, narrative or autobiographical self. (shrink)

In this paper, we study the auction to allocate an indivisible good when each potential buyer has a private and independent valuation for the item and suffers a negative externality if a competitor acquires it. In that case, the outside option of each buyer is mechanism-dependent, which implies that participation is endogenous. As several works in the literature have shown, the optimal auction entails strong threats to induce full entry and maximal expected revenue. This results from the full commitment assumption, (...) which ensures that threats are credible. We show that absent credible threats, the entry process does not lead to full participation: the equilibrium entails screening of agents in the entry stage and a trade-off between reserve prices and entry fees. Besides, we discuss the conditions under which the impossibility to use threats does not prevent the seller from ensuring a minimal screening and reaching a high expected revenue. (shrink)

The phenomenon of consciousness has received through the centuries a profusion of interpretations, engaging researchers across many disciplines. Nevertheless, consensus still floats at large. The aim of the present work is therefore twofold. Through the review of a selected number of existing proposals, it will first be considered the extents of their reciprocal compatibility, tentatively shaping an integrated, theoretical profile of consciousness. A new theory, the Endogenous Feedback Network will consequently be introduced which, besides being able to accommodate the main (...) tenets of the reviewed theories, appears able to compensate for the explanatory gaps they leave behind. The EFN proposes consciousness as the phenomenon emerging from a distinct neural network broadcasting the changes associated to mental activations across the brain. It additionally argues for the need to include a 5th element to Ned Block’s taxonomy that is, non-cognitive consciousness. (shrink)

This paper examines the theoretical background and actual behavior in a gaming tournament with endogenous timing where a person has more incentive, structure, and time to form a strategy. The baseline treatment suggests that subgame perfection is a reasonable predictor of behavior –- subjects made 170 of 208 theoretically predicted choices of best actions, with the majority of mistakes made in timing choices by the players who did not survive the cut to the second round. Four sensitivity treatments established that (...) the design feature that lead to more predictable behavior was time to think –- 745 of 960 correctly predicted decisions with more time versus 595 of 960 with less time. A random effects Probit model suggests that the key design feature that closed the gap between predicted and observed behavior was not necessarily the non-linear payoffs created by the tournament design, but rather that the key was providing people with more time to think about their strategy. (shrink)

Several studies have revealed the presence in human DNA of thousands of endogenous retrovirus genomes, or HERVs. Many HERVs are related to extant retroviruses that infect other vertebrates and some have been present in the germ line of primates for millions of years. Although the HERVs that have been isolated are defective and thus do not encode infectious retroviruses, there may be HERVs that are capable of infection. In addition, because HERVs are so ancient in the human lineage, evolution of (...) the human genome may have included the acquisition of some HERV genes for strictly cellular functions. (shrink)

Lowest-unique sealed-bid auctions are auctions with endogenous participation, costly bids, and the lowest bid among all unique bids wins. Properties of symmetric NEs are studied. The symmetric NE with the lowest expected gains is the maximin outcome under symmetric strategies, and it is the solution to a mathematical program. Comparative statics for the number of bidders, the value of the item and the bidding cost are derived. The two bidders’ auction is equivalent to the Hawk–Dove game. Simulations of replicator dynamics (...) provide numerical evidence that the symmetric NE with the lowest expected gains is also asymptotically stable. (shrink)

Malignant cells are characterized by an increased content of endogenous formaldehyde formed as a by‐product of biosynthetic processes. Accumulation of formaldehyde in cancer cells is combined with activation of the processes of cellular formaldehyde clearance. These mechanisms include increased ALDH and suppressed ADH5/FDH activity, which oncologists consider poor and favorable prognostic markers, respectively. Here, the sources and regulation of formaldehyde metabolism in cancer cells are reviewed. The authors also analyze the participation of oncoproteins such as fibulins, FGFR1, HER2/neu, FBI‐1, and (...) MUC1‐C in the control of genes related to formaldehyde metabolism, suggesting the existence of two mutually exclusive processes in cancer cells: 1) production and 2) oxidation and elimination of formaldehyde from the cell. The authors hypothesize that the study of the anticancer properties of disulfiram and alpha lipoic acid – which affect the balance of formaldehyde in the body – may serve as the basis of future anticancer therapy. (shrink)

The beginning of the twenty first century has been characterized by the expansion of economics, politics and institutional relations. Using international case studies, this book illustrates the local answer to the challenge of increasing competition. The book introduces the idea of endogenous development, identifying the theoretical roots and defining its main features. It then goes on to indicate how this concept can be used to understand economic dynamics, and to show how the concept is relevant in economic analysis and policy (...) implementation in times of globalization. This work will be of essential interest to academics and policy-makers in planning and development economics. (shrink)

Does the desirability of social institutions for public goods provision depend on the extent to which they include mechanisms for endogenous enforcement of cooperative behavior? We consider alternative institutions that vary the use of direct punishments to promote social cooperation. In one institution, subjects participate in a public goods experiment in which an initial stage of voluntary contribution is followed by a second stage of voluntary, costly sanctioning. Another institution consists of the voluntary contribution stage only, with no subsequent opportunity (...) to sanction. In a third stage subjects vote for which institution they prefer for future interactions: do they prefer one that does allow sanctions or one that does not allow sanctions? Our results show that even though sanctions are frequently used when available, the clear majority of individuals vote for the institution that does not allow sanctions. Thus, a distinction is required between the principles that guide the choice of institutions and the principles that apply to actions guided by institutions. Our results indicate that it is the wealth generated by the institution that determines its desirability. (shrink)

The empirical relationship between a firm’s social performance and its financial performance is still not well established in the literature. Despite more than 30 years of research and more than 100 empirical studies on the issue, the results are still mixed. We argue that the heterogeneous results found in previous studies are not due exclusively to problems related with the measurement instruments or the samples used. Instead, we posit that a more fundamental problem related with the endogeneity of social (...) strategic decisions could be driving most of the empirical findings. We show that, using a panel data of 658 firms from 1991 to 2005, how some of the results found in previous research change, and some are even reversed when endogeneity is properly taken into account. (shrink)

We contrast reactive and endogenously active perspectives on brain activity. Both have been pursued continuously in neurophysiology laboratories since the early 20thcentury, but the endogenous perspective has received relatively little attention until recently. One of the many successes of the reactive perspective was the identification, in the second half of the 20th century, of the distinctive contributions of different brain regions involved in visual processing. The recent prominence of the endogenous perspective is due to new findings of ongoing oscillatory activity (...) in the brain at a wide range of time scales, exploiting such techniques as single-cell recording, EEG, and fMRI. We recount some of the evidence pointing to ways in which this endogenous activity is relevant to cognition and behavior. Our major objective is to consider certain implications of the contrast between the reactive and endogenous perspectives. In particular, we relate these perspectives to two different characterizations of explanation in the new mechanistic philosophy of science. In a basic mechanistic explanation, the operations of a mechanism are characterized qualitatively and as functioning sequentially until a terminating condition is realized. In contrast, a dynamic mechanistic explanation allows for non-sequential organization and emphasizes quantitative modeling of the mechanisms's behavior. For example, with appropriate parameter values a set of differential equations can be used to demonstrate ongoing oscillations in a system organized with feedback loops. We conclude that the basic conception of mechanistic explanation is adequate for reactive accounts of brain activity, but dynamical accounts are required to explain sustained, endogenous activity. (shrink)

Can we build endogenous expectations about the locus of occurrence of a target without being able to describe them? Participants performed cue–target detection tasks with different proportions of valid and invalid trials, without being informed of these proportions, and demonstrated typical endogenous effects. About half were subsequently able to correctly describe the cue–target relationships . However, even non-verbalizer participants showed endogenous orienting with peripheral cues , not depending solely on practice . Explicit instructions did not bring about dramatic advantages in (...) performance .With central symbolic cues, only verbalizers showed reliable endogenous effects . We concluded that endogenous orienting with peripheral cues can occur independently of participants developing explicit hypotheses about the cue–target relationships. (shrink)

Remnants of ancient retroviral infections during evolution litter all mammalian genomes. In modern humans, such endogenous retroviral (ERV) sequences comprise at least 8% of the genome. While ERVs and other types of transposable elements undoubtedly contribute to the genomic “junk yard”, functions for some ERV sequences have been demonstrated, with growing evidence that ERVs can be important players in gene regulatory processes. Here we focus on one particular large family of human ERVs, termed HERVH, which several recent studies suggest has (...) a key regulatory role in human pluripotent stem cells. Remarkably, this is not the first instance of an ERV controlling pluripotency. We speculate as to why this convergent evolution might have come about, suggesting that it may reflect selection on the virus to extend the time available for transposition. Alternatively it may reflect serendipity alone. (shrink)

This paper studies a sender-receiver game in which both players want the receiver to choose the state-optimal action. Before observing the state, the sender observes a “contextual signal,” a payoff-irrelevant signal that correlates with states and is imperfectly shared with the receiver. Once the sender observes the state, the sender sends a message to the receiver, incurring a small messaging cost. It is shown that there is no miscommunication in any efficient equilibrium if the messaging cost is uniform or contextual (...) information is poorly shared between players. However, if the messaging costs are different between some messages, and contextual information can affect the probability ranking of states and is shared reasonably well, any efficient equilibrium that favors the sender exhibits miscommunication. Furthermore, the messages that cause miscommunication can be coarse or ambiguous, depending on how well players share contextual information. (shrink)

Through a series of examples, we illustrate some important drawbacks that the action model logic framework suffers from in its ability to represent the dynamics of information updates. We argue that these problems stem from the fact that the action model, a central construct designed to encode agents’ uncertainty about actions, is itself effectively common knowledge amongst the agents. In response to these difficulties, we motivate and propose an alternative semantics that avoids them by endogenizing the action model. We discuss (...) the relationship between this new framework and action model logic, and provide a sound and complete axiomatization of several new logics that naturally arise. (shrink)

In Africa, the human person is the supreme force, the most powerful and dominant among all created beings. While this decreed power makes the lower beings subservient to humanity, it is only intended to be a source of harmony in the advancement of the hospitality and the joy of the human species. Today, however, the traditional lifestyles of Africans are threatened with virtual extinction by insensitive development over which the indigenous peoples have no participation. Africa has not only acquiesced a (...) scientific technology that has developed its own laws far removed from the known system of nature, it has no self-limiting principle in terms of size, speed and violence to nature and humanity. Consequent upon this incongruity, the machine has replaced the human person thus degrading the ecology and resources necessary for harmonious living. This chapter argues that, African endogenous knowledge is strategic heritage resource to salvage the technologically abused environment for sustainable agro-ecological living. The chapter argues further that African endogenous knowledge system encodes environmental management and policies for resource development in Africa’s complex and ageing ecological system. In doing this, we engage in conversation about current and potential land sovereignty work in African Indigenous communities. This will achieve food security and improved nutrition, promote sustainable agriculture and improved economic status of the African indigenous farmer. We conclude that, in seeking the whole from the units of the earth resources through cultivation of the soil, the African derives high credit balance of spiritual good, virtuous life, self-reliance, courage and moral integrity. (shrink)

Macroeconomic events often require individuals and policy-makers to make decisions that they are not accustomed to making. For example, a sovereign debt crisis makes it necessary to either default on government debt, increase taxes, cut public spending or to impose a mixture of these measures. I argue that decisions on such matters are not derived from deep preferences; they require reflections and judgement under uncertainty. Past experiences and the interaction with other individuals are likely to influence the salience of preferences (...) in the situations of decision making. Using a simple model, I illustrate how the salience of preferences changes with different degrees of individuality and conformity. Individuality is associated with the importance of private habits, while conformity is related to the perceived dissonance between initial intuitions and social opinions. The results obtained from simple simulation exercises stress that a high degree of conformity or a low degree of individuality may lead to overreactions when social opinion makers err for a short period of time. At the same time, a low degree of conformity or a high degree of individuality or leads to delayed adjustments to new circumstances. (shrink)

We expose some representations and practices related to the natural environment among Nahua peasants in a village located at the western boundary of Puebla and Guerrero states, in Mexico. Information was obtained by individual interviews and focal groups' work, following an open guide with ecological items considered as rooted in Mesoamerican cultures. The use of some local, vegetal resources, and the local perception of changes, mainly in the water availability, is documented. Survival strategies involve ancestral representations and material products, and (...) entail a high grade of pragmatism. “Natural environment” is framed in a local culture that involves relational and sacred dimensions, usually omitted in other approaches. Hence, for the Temalac peasants, there is no dissection, at an operative level, between “natural facts” and personal or social ones, being these often considered as determinant for the quality and accessibility of resources and weather conditions. We discuss the challenge for these elements posed by a growing migration rate and an increasing external influence. (shrink)

The Nash counterfactual considers the question: what would happen were I to change my behaviour assuming no one else does. By contrast, the Kantian counterfactual considers the question: what would happen were everyone to deviate from some behaviour. We present a model that endogenizes the decision to engage in this type of Kantian reasoning. Autonomous agents using this moral framework receive psychic payoffs equivalent to the cooperate-cooperate payoff in Prisoner’s Dilemma regardless of the other player’s action. Moreover, if both interacting (...) agents play Prisoner’s Dilemma using this moral framework, their material outcomes are a Pareto improvement over the Nash equilibrium. (shrink)

In this paper we suggest a model of sequential auctions with endogenous participation where each bidder conjectures about the number of participants at each round. Then, after learning his value, each bidder decides whether or not to participate in the auction. In the calculation of his expected value, each bidder uses his conjectures about the number of participants for each possible subgroup. In equilibrium, the conjectured probability is compatible with the probability of staying in the auction. In our model, players (...) face participation costs, bidders may buy as many objects as they wish and they are allowed to drop out at any round. Bidders can drop out at any time, but they cannot come back to the auction. In particular we can determine the number of participants and expected prices in equilibrium. We show that for any bidding strategy, there exists such a probability of staying in the auction. For the case of stochastically independent objects, we show that in equilibrium every bidder who decides to continue submits a bid that is equal to his value at each round. When objects are stochastically identical, we are able to show that expected prices are decreasing. (shrink)

A number of observations have led researchers to postulate that, despite being replication‐defective, human endogenous retroviruses (HERVs) may have retained the potential to cause or contribute to disease. However, mechanisms of HERV pathogenicity might differ substantially from those of modern infectious retroviruses or of the infectious precursors of HERVs. Therefore, novel pathways of HERV involvement in disease pathogenesis should be investigated. Recent technological advances in sequencing and bioinformatics are making this task increasingly feasible. The accumulating knowledge of HERV biology may (...) also facilitate the definition and general acceptance of criteria that establish HERV pathogenicity. Here, we explore possible mechanisms whereby HERVs may cause disease and examine the evidence that either has been or should be obtained in order to decisively address the pathogenic potential of HERVs. (shrink)

This paper presents a new theoretical justification for the Cournot–Bertrand model to arise in equilibrium when firms have, at the outset, the same cost structure and sell symmetrically differentiated products. The Cournot–Bertrand model assumes some firms compete on price, adjusting their production to meet demand, while others set quantities and let their price adjust until market equilibrium is reached. We show that this may occur endogenously due to the possibility of entry, which may be deterred when some of the incumbents (...) decide to set prices, while others free ride on this behavior and choose quantities. (shrink)

In recent years, in the era of multiple crises, there are many political parties and leaders that use conspiracy theories in their discourse, trying to explain facts and figures on politics, economy, society, environment and space. There is an ongoing debate in populism studies on the possible connection between the populist phenomenon and conspiracy theories, thus creating two main theoretical camps. On the one hand, there are many scholars who recognize a strong correlation between the two phenomena, with some of (...) them believing that they are directly equated. On the other hand, there are several researchers who consider populism as a phenomenon with its own unique essence without predetermined characteristics. Hence, the question that arises here is: Is conspiracism endogenous to populism, or not? In this article, I first look at the definitions of conspiracy theories/conspiracism and populism, attempting to avoid stereotypical readings. After that, I highlight the discussion that takes place in academia around the internal features of the populist phenomenon and its possible connection with conspiracism, with the aim of showing that populism presents a unique logic, without a necessary connection to conspiracism. Finally, I focus on the Greek case of recent years, describing an example where the concept of conspiracy theory became a polemical tool against political rivals, negatively affecting politics and society. My analysis is based on post-structuralist theory and methodological tools of the Essex School of Discourse Analysis, taking into account aspects of other approaches to populism. (shrink)

It is widely recognized that computational theories of learning must posit the existence of a priori constraints on hypothesis selection. The present article surveys the theoretical options available for modelling the dynamic process whereby the constraints have their effect. According to the 'simplicity' theory (exemplified by Fodor's treatment), hypotheses are preference-ordered in terms of their syntactic or semantic properties. It is argued that the same explanatory power can be obtained with a weaker (hence better) theory, the 'minimalist' theory, which dispenses (...) with the preference ordering. According to the 'finitistic' theory, the learner is capable of generating only finitely many hypotheses for evaluation. Chomsky maintains that the occurrence of errorless learning in language acquisition necessitates a finististic explanation. Once again, there is a weaker theory that explains the same data. Finally, Goodman's argument to the effect that there cannot be a computational theory of learning is examined and rejected. (shrink)

We argue that the roles of attacker and defender in asymmetric intergroup conflict are structurally ambiguous and their perception is likely to be subjectively biased. Although this allows for endogenous selection into each role, we argue that claiming the role of the defender likely is more advantageous for conflict participants.