McKay & Dennett's (M&D's) description of beliefs, and misbeliefs in particular, is a commendable contribution to the literature; but we argue that referring to beliefs as adaptive or maladaptive can cause conceptual confusion. “Adaptive” is inconsistently defined in the article, which adds to confusion and renders it difficult to evaluate the claims, particularly the possibility of “adaptive misbelief.”

Carruthers is right to reject the idea of a dedicated piece of cognitive architecture with the exclusive job of reading our own minds. But his mistake is in trying to explain introspection in terms of any one mindreading system. We understand ourselves in many different ways via many systems.

An evolutionary psychological perspective drawing on sexual selection theory can better explain sex differences in aggression and violence than can social constructionist theories. Moreover, there is accumulating evidence that, in accordance with predictions derived from sexual selection theory, men modulate their willingness to engage in risky and violent confrontations in response to cues to fitness variance and future prospects.

Talk of linguistic universals has given cognitive scientists the impression that languages are all built to a common pattern. In fact, there are vanishingly few universals of language in the direct sense that all languages exhibit them. Instead, diversity can be found at almost every level of linguistic organization. This fundamentally changes the object of enquiry from a cognitive science perspective. This target article summarizes decades of cross-linguistic work by typologists and descriptive linguists, showing just how few and unprofound the universal characteristics of language are, once we honestly confront the diversity offered to us by the world's 6,000 to 8,000 languages. After surveying the various uses of “universal,” we illustrate the ways languages vary radically in sound, meaning, and syntactic organization, and then we examine in more detail the core grammatical machinery of recursion, constituency, and grammatical relations. Although there are significant recurrent patterns in organization, these are better explained as stable engineering solutions satisfying multiple design constraints, reflecting both cultural-historical factors and the constraints of human cognition.

Linguistic diversity then becomes the crucial datum for cognitive science: we are the only species with a communication system that is fundamentally variable at all levels. Recognizing the true extent of structural diversity in human language opens up exciting new research directions for cognitive scientists, offering thousands of different natural experiments given by different languages, with new opportunities for dialogue with biological paradigms concerned with change and diversity, and confronting us with the extraordinary plasticity of the highest human skills.

John Bowlby's use of evolutionary theory as a cornerstone of his attachment theory was innovative in its day and remains useful. Del Giudice's target article extends Belsky et al.'s and Chisholm's efforts to integrate attachment theory with more current thinking about evolution, ecology, and neuroscience. His analysis would be strengthened by (1) using computer simulation to clarify and simulate the effects of early environmental stress, (2) incorporating information about non-stress related sources of individual differences, (3) considering the possibility of adaptive behavior without specific evolutionary adaptations, and (4) considering whether the attachment construct is critical to his analysis.

Carruthers claims that global workspace theory implies that sensory states, unlike propositional attitudes, are introspectible in a non-interpretative fashion. I argue that this claim is false, and defend a strong version of the “mindreading is prior” model of first-person access, according to which the self-ascription of all mental states, both propositional and sensory, is interpretative.

I present the so-called Verb-Object Constraint as a serious proposal for a true linguistic universal. It provides an example of the kind of abstraction in linguistic analysis that seems warranted, of how different languages can confirm such a universal in different ways, and why approaches that avoid all abstractness miss important linguistic generalizations.

If parenting behavior influences attachment, then parental investment (PI) theory can predict sex differences and distributions of attachment styles across cultures. Trivers-Willard, local resource competition, and local resource enhancement models make distinct predictions for sex-biased parental responsiveness relevant to attachment. Parental investment and attachment probably vary across cultures in relation to “local fitness currencies” for status, wealth, and well-being.

The mere fact that a particular aspect of mind could offer an adaptive advantage is not enough to show that that property was in fact shaped by that adaptive advantage. Although it is possible that the tendency towards positive illusion is an evolved misbelief, it it also possible that positive illusions could be a by-product of a broader, flawed cognitive mechanism that itself was shaped by accidents of evolutionary inertia.

Dream research shows sex differences in dream aggression that fit very well with the findings for waking-life aggressive behaviour. Dream studies are a valuable tool for investigating variables underlying the sex difference in aggression. One might argue that studying dream aggression might be even more promising because aggression in dreams is not socially labelled, as being aggressive in waking life is.

Social roles theorists claim that differences between the sexes are of limited consequence. Such misperceptions lead to misunderstanding the important role of sexual selection in explaining phenotypic differences both between species and within humans. Countering these claims, we explain how sexual dimorphism in humans affect expressions of artistic display and patterns of male and female aggression across the ovulatory cycle.

Judgments vary in the extent to which they are based on interpretation versus relatively direct access to mental contents. That is, a judgment might require a trivial amount of interpretation (e.g., translating one's immediately accessible “inner speech”) or a rather substantial amount of confabulation. Recognizing this continuum of interpretation underlying judgment could be more fruitful than debating a categorical introspection versus interpretation distinction.

Evans & Levinson (E&L) argue against Universal Grammar on the basis of language diversity. A related and fundamental issue is whether the language input provides sufficient information for a child to acquire it. I briefly discuss the more integrated approaches to language acquisition which focus on the mechanisms, and research showing that input cues provide valuable information for the language learner.

The translation of research findings from other primates to humans, and from infants to adults within our own species, requires great care. If the many neurological, behavioral and adaptive distinctions between these groups are not precisely defined and considered, erroneous conclusions about evolutionary history and developmental processes may result.

I highlight and amplify three central points that McKay & Dennett (M&D) make about the origin of failures to perform biologically proper functions. I question whether even positive illusions meet criteria for evolved misbelief.

Del Giudice's examination of sex differences in reproductive strategy within an attachment context is well taken. Sex has been studied as behavior within romantic relationships, but attachment styles should also be reflected in strategic behavior within relationships that are sexual. This seems particularly true within adolescence, and sex differences may be better reflected as differences in correlation patterns of process variables than as main effects models.

At the heart of the debate between social role theorists and evolutionary psychologists is whether natural selection has designed the minds of the sexes differently to some interesting extent. In this commentary I describe the standards of evidence for both the positive and negative claims. In my opinion, Archer has met the standard for designed sex differences in intrasexual conflict.

Evans & Levinson (E&L) are right to hold theories of language accountable for language diversity, but typological data alone cannot determine the structure of mental phonological grammars. Grammatical universals are nonetheless testable by formal and experimental methods, and the growing research in experimental phonology demonstrates the viability of a comparative experimental evaluation of the Universal Grammar (UG) hypothesis.

In their target article, McKay & Dennett (M&D) conclude that only “positive illusions” are adaptive misbeliefs. Relying on overly strict conceptual schisms (deficit vs. motivational, functional vs. organic, perception vs. belief), they prematurely discount delusions as biologically adaptive. In contrast to their view that “motivation” plays a psychological but not a biological function in a two-factor model of the forming and maintenance of delusions, we propose a single impairment in prediction-error–driven (i.e., motivational) learning in three stages in which delusions play a biologically adaptive role.

Peter Carruthers correctly claims that metacognition in humans may involve self-directed interpretations (i.e., may use the conceptual interpretative resources of mindreading). He fails to show, however, that metacognition cannot rely exclusively on subjective experience. Focusing on self-directed mindreading can only bypass evolutionary considerations and obscure important functional differences.