Conceived as a field of inquiry, evolutionary psychology can be characterised as the ‘evolutionary-oriented study of human behaviour and cognition’. On such an understanding evolutionary psychology can recognise several logically independent levels of explanation, each in response to different kinds of question. Hence, no account at any given level of explanation has entailments for other levels; neither does it require commitment to any given explanations at other levels. Indeed, as David Buller remarks, such an understanding is not characterised by particular doctrines pertaining to human behaviour and cognition but by ‘the kinds of question it asks about them’. According to some, however, evolutionary psychology entails specific assertions pertaining to ‘the nature and evolution of the human mind’ . Understood in the latter sense, evolutionary psychology is best described as a research programme. Given a choice between two differing conceptions of evolutionary psychology, it is prudent to adopt the option with the most plausibility. My thesis is that:
- Firstly, certain basic tenets of evolutionary psychology understood as a research programme face contain poorly justified assumptions, which the methodology of functional analysis is poorly equipped to test.
- Secondly, that the problematic nature of said basic tenets is at least in part reflected by the research programme’s thus far inconclusive findings regarding the nature of the human mind;
- Finally, I will conclude that, given the contested nature of the arguments employed in support of its latter understanding, it is likely the case that evolutionary psychology is best understood in the broad sense as a field of inquiry.
In the interest of avoiding conflation, I will adopt Buller’s naming convention and distinguish the research programme from the field of inquiry through capitalization. Henceforth, I will refer to the research programme as ‘Evolutionary Psychology’ (capitalized).
Due to space constraints, I am presently unable to provide the full account of Evolutionary Psychology’s fundamental assertions necessary for a comprehensive argument. As such, my discussion of the research programme’s hard core consists of an evaluation of those assertions that are most readily refuted. On a simplified view, Evolutionary Psychologists can be characterised as positing the existence of a universal human nature consisting of evolved domain-specific cognitive programs that adapted due to the selection pressures of the EEA (Environment of Evolutionary Adaptedness). The EEA has been described as placed by Evolutionary Psychologists at ‘some time in the Pleistocene’, which extended over a duration of around 2.5 million years. Given the relatively recent advent of modern environments some forty thousand years ago, it is implied that human behaviour is geared to produce adaptive outcomes not in modern society but in stone-age environments. Furthermore, given the domain-specific nature of the proposed cognitive programs, the human mind has a massively modular structure. This posit is conventionally known as the ‘massive modularity hypothesis’. To illustrate this last point, an analogy can be made with our bodily organs. Each organ evolved by the process of natural selection to achieve a specific purpose and no organ can be said to perform a general purpose. Likewise, the human mind is comprised of cognitive programs or modules, each of which is adaptive to a specific purpose relevant to the selective pressures of the EEA. There is also a subsequent reductionist claim that cultural and social phenomena can be understood in terms of said cognitive programs. Setting aside the massive modularity hypothesis for discussion at a later point, I will begin with a set of criticisms pertaining to the Evolutionary Psychologist’s account of the EEA.
One of the foremost assumptions of the Evolutionary Psychologist’s account of the EEA is that ‘current human social adaptations’ are sourced form the Pleistocene, however this position suffers from certain empirical issues. Granted that different components of the human mind evolved to meet the pressures of varying environments, identifying the EEA with one particular period of human history may lead to descriptions of phenomena that do not account for the possibility that some components arose at an earlier point in our evolutionary history. It has been argued that neurological evidence suggests the evolution of most ‘special-purpose mechanisms’ in the brain occurred at an earlier point in the history of our evolution than the advent of Pleistocene EEAs . For instance, Panksepp et al make the point that the postulation by Cosmides and Tooby of a ‘fear module’ that arose after the development of ‘sophisticated cognitive capacities’ does not account for neurological evidence that a modularized fear response already exists at the sub-cortical level. Given that the sub-cortical circuity of the human brain contains common structures which are shared with other mammals and thus must have developed at an earlier point in our ancestry, the role of Pleistocene EEAs in the development of a fear module is questionable.
Another criticism can be directed at Evolutionary Psychology’s assumptions about the maladaptive-ness of human behaviour to modern environments. Given that the modern environment is one that has been shaped by human behaviour, if the human brain is structured in such a way as to produce behaviours that lead to the creation of this modern environment, then there is no a priori reason for the implication that ‘current human social adaptations’ are not adaptive to modern environments. Indeed, Barrett points out that this assumption ‘has no firm evidence to support it’. Hence, this claim of Evolutionary Psychology is one that must be tested empirically rather than taken as a given. However, in light of criticisms regarding Evolutionary Psychology’s methodology of functional analysis to follow, it is unclear whether the research programme can provide such evidence as required.
A key procedure of Evolutionary Psychology is the use of functional analysis to verify claims that certain cognitive mechanisms in fact evolved as adaptations in response to particular recurring adaptive problems in the EEA. This method consists of the use of evolutionary reasoning to postulate certain adaptive problems faced by our ancestors in the EEA, and to infer or ‘reverse engineer’ the cognitive processes that could have evolved as adaptations to resolve those problems. Psychological tests are then carried out in order to confirm the existence of the proposed cognitive mechanisms in modern humans. However, even if such psychological tests established to a good degree of confidence the existence of certain cognitive mechanisms, it remains an open question whether the proposed cognitive mechanisms are adaptations at all rather than exaptations – evolved mechanisms that acquire functions differing from those for which they were selected. Furthermore, it is questionable whether studies following this rubric successfully establish the existence of their postulated cognitive mechanisms in the first place as the evidence provided is often inconclusive. What follows is a critical account of one such study, owed to Buller.
It is quite uncontroversial that the evolution of the reciprocal altruism behavioural trait creates a situation that selects for ‘cheaters’ – who enjoy the fitness benefits of another’s altruistic act without reciprocating their behaviour. This in turn creates selection for a trait that can aid in the detection of cheaters. Hence, Buller notes that Evolutionary Psychologists have postulated the existence of a ‘cheater detection module’. The evidence presented for said cognitive mechanism is derived from data collected through the ‘Wason selection task’, whereby test subjects are presented with four double-sided cards displaying ‘information of the form P, not-P, Q and not-Q’ as well as a formulation of the conditional ‘if P, then Q’; they are given instructions to the effect that they must flip over only those cards necessary in order to determine the truth of the conditional. Since the only way in which a conditional can be false is if it the case the P and not-Q, the only way to determine its truth is to flip the cards corresponding to the form P, and not-Q to see whether the information on the other side negates the conditional. In the experiment, two sets of cards were used – one with abstract content and another that framed the information as a ‘social contract problem’ – a hypothetic situation which involves the acceptance of some social benefit in return for an agreement to fulfil some obligation. When posed with an abstract problem, only four percent of subjects selected the correct combination of cards, whereas when the information was presented with a social contract problem, seventy-three percent of subjects selected the correct cards, even though the logical form of the information remained the same. The data appears to suggest that subjects respond not to the logical form of conditionals but to their content, a result suggesting that the mind does not operate under logical principles but in accordance with a modulated structure. Particularly, it is claimed that the improved performance in subjects presented with social content in relation to those presented with abstract content suggests the existence of a ‘cheater detection module’.
Regardless, the results are insufficient as evidence for a modulated mind as the apparent ‘content effect’ displayed in the data supporting the hypothesis is in fact a result of the conflation of ‘indicative conditionals’, used in the abstract problem, with ‘deontic conditionals’ used in the ‘social contract’ problem. These two types of ‘conditionals’ in fact possess differing logical forms. Consider the following sentences:
1) If I am carrying an umbrella, then it is raining
2) If you drink alcohol, then you must be over 18 years of age
The first, (1), is indicative; it’s propositional content is that Q: ‘’it is raining’’ is conditional upon P: ‘’I am carrying an umbrella’’, and its negation entails P: ‘’I am carrying an umbrela’’, and not-Q: ‘’it is not raining’’. On the other hand, the second, (2), is deontic; it is not an expression of a proposition but rather expresses an obligation. Unlike (1), the negation of (2) does not entail P, it only entails that ‘’you need not be over 18 years of age to drink alcohol’’ – nothing about this statement entails that P: ‘’you drink alcohol’’. In fact, Buller cites studies by P.W Cheng, K.J Holyoak; K.I Manktelow, D.E Over; and D. Sperber, et al with results showing that subjects presented with indicatives expressing ‘practical relationships between P and Q’ obtained a similar percentage of correct responses to that obtained in responses to deontic conditionals. In light of this criticism, the results of the Watson selection task are not in fact inconsistent with the hypothesis that humans reason in accordance with general logical principles, and therefore cannot be taken as evidence of a modular mind.
In conclusion, I have shown that the understanding of evolutionary psychology in the narrow sense as a research programme is problematic at best. First, I have argued that Evolutionary Psychology’s account of the origin of our social adaptations rests on questionable assumptions about the nature of its proposed Pleistocene EEA, leading to postulations of cognitive modules which do not account for the evolution of functionally equivalent components at a prior point in our evolutionary history. Furthermore, I have established that it relies on unfounded assumptions regarding the maladaptive nature of human behaviours. Second, I have argued that the methodology of functional analysis cannot reveal whether the research programme’s posited cognitive mechanisms are in fact adaptations, implying that such claims regarding their nature are overattributions. Finally, I have shown that studies following the methodology are inconclusive. It follows that there is more plausibility to the claim that evolutionary psychology is best understood as a field of inquiry rather than as a research programme.