Divided into eight chapters and at 523 pages in length, Reptiles with a Conscience: The Coevolution of Religious and Moral Doctrine is an ambitious work produced by an equally ambitious young philosopher, Nathan Cofnas. The core thesis of the work is as straightforward as it is revolutionary: different religious movements evolved along convergent moral pathways, despite there being virtually no contact between the founding stocks of these religions. This is because during the course of their evolution, distinct religions encountered specific problems of a philosophical and theological nature which could be solved logically in such a way that led to the same solutions being integrated into otherwise disparate theologies.

Judaism and Hinduism feature prominently in this work. Many aspects of their moral and cultural systems are compared and found to be startlingly similar. For example, both Judaism and Hinduism incorporate reincarnation into their doctrines. Cofnas argues that this is intentional, as it serves to solve a particular theological problem, i.e. what could be termed the need for ‘post-mortem’ justice. Another example is that both Hinduism and Judaism utilize the concept of free will to resolve yet another theological issue: the theodicy problem which maintains that a deity or deities cannot be simultaneously perfectly good and omnipotent owing to the presence of evil in the world. The free will solution is based on the idea that evil serves an ultimately good purpose in that it permits people to make the morally correct choices. It is argued that as omnipotent deities cannot perform logically contradictory acts (such as create objects or forces that are immovable or irresistible to them), deities cannot therefore create a world in which people are free to make moral choices and in which they are predestined always to make such choices (like automata). Hinduism and Judaism also spawned analogous breakaway movements in the form of Buddhism and Christianity, both of which are centred around the person of their founders, and are similar to one another in many subtle ways, including in their criticisms of their parent religions.

What is so revolutionary about these observations? The revolution in thinking comes from Cofnas' model to account for these cultural analogies. Cofnas argues that it was not the currently vogue moral intuitions from evolutionary psychology (essentially modular, heuristics that would have been selected on the basis of their ability to solve recurrent social exchange type problems) that gave rise to this cultural convergence. Instead Cofnas argues that many of the problems encountered by evolving religions are logically solvable, and via the application of open-ended and domain-general abstract reasoning or general intelligence these problems can be, and are, solved in analogous ways, despite differences between peoples. Cofnas does not reject moral intuitions; he simply argues that on their own they are not sufficient to account for the striking convergent cultural evolution of these diverse religious tendencies. This is because moral intuitions cannot themselves be used to solve abstract or evolutionarily novel problems straddling multiple evolutionary domains; however, they might assist in framing such problems. This is perhaps best illustrated in the contrasts between ‘parent’ and ‘offspring’ religions (such as Judaism and Christianity and also Hinduism and Buddhism). These ‘offspring’ religions evolved an explicit moral framework that was adaptive given novel circumstances. For example Christianity consciously de-emphasized the more evolutionarily familiar tribalistic orientation of Judaism whilst simultaneously cultivating a proselytizing ethos that resonated with large numbers of people. Furthermore, it provided intellectual challenges to those who might take a leadership role in the religion (i.e. join the priesthood). This particular ‘design element’ of the Christian moral framework solved an open ended and also highly evolutionarily novel problem, i.e. how to get your religion into the minds of as many non-kin as possible. The ‘one size fits all’ Christian cultural template is evidently therefore an effective solution to this problem as it has given Christianity the capacity to proliferate to the point where it is currently the world's biggest religion. Whilst Buddhism hasn't enjoyed the same level of success as Christianity in terms of proliferation, Buddhism also rejected the tribalistic distinctions of its progenitor religion, and was thus able to attract large numbers of converts from outside its country of origin.

Another significant source of novelty in Cofnas' book is in his discussion of the moral foundations of political liberalism and conservatism. He argues that religious conservatives and liberals have very different conceptions of the role of deities in the world. The contrasts are extremely interesting. For example, a parallel is drawn between the conservative belief in the capacity for societies to spontaneously order their economic affairs along free-market lines and a belief in a God who is imminent in nature. Essentially, according to Cofnas, part of being conservative is having a belief that there are benevolent and intangible forces that shape and organize the world such that the best outcome always results from just ‘going with the flow’ so to speak. Liberals on the other hand have a fundamentally more ‘chaotic’ view of both the natural and supernatural worlds, and have a tendency towards belief in the idea that the various phenomena in the world are the consequence of what could be termed ‘piecemeal forces’, which do not combine necessarily in a harmonious or optimal manner. The liberal tends therefore to prefer human control over nature and society, and is distrustful of concepts like the invisible hand and human nature. There are two interesting implications of this. Firstly, Cofnas argues that the ‘piecemeal forces’ model of phenomenology is also at the root of more polytheistic and animistic belief systems. Whilst he does not make explicit this connection, the idea that the collectivistic and egalitarian moral foundations of liberalism had their origins in the Pleistocene, whereas the more individualistic and dominance-oriented moral foundations of conservatism had their origins subsequently in the Holocene, especially amongst populations having to cope with harsher environments in which extended family formation was costly, is compatible with the idea that animistic religions were likely to have been practised by humans living in the Pleistocene. Hence such religious practices were probably an inevitable manifestation of everybody exhibiting essentially liberal moral foundations. Secondly, Cofnas argues that religious liberals are more likely to believe in an impersonal and aloof or remote God, which in turn accords with the liberal ‘piecemeal forces’ phenomenology, as it is a logical solution to the contradiction presented by the intuitive belief in a higher power on the one hand, and evidence of poor design in the world coupled with evil on the other. By the same token liberals are also more likely to simply disbelieve in God, although interestingly they also tend to make a moral virtue out of such disbelief, which makes sense of the proselytism characteristic of explicitly irreligious and also predominantly liberal movements such as the New Atheism.

I was especially impressed with Cofnas' discussion of the relationship between intelligence and religiosity. This is especially timely as despite the existence of a number of studies into these relationships, no serious attempts have been made to distil a coherent theory. Cofnas flat-out rejects the simplistic idea that religiosity and IQ are negatively correlated owing purely to higher religiosity appealing more to those with lower IQs than those with higher IQs. He argues instead that whilst certain conceptually simple and more dogmatic forms of religiosity are more likely to resonate with those of lower IQ, the opposite should be true of religions that make a virtue of scholarly application, such as Judaism and Hinduism, in which ‘full’ membership is contingent upon mastery of the relevant religious texts and in which there are even mystery texts, seemingly designed specifically to be accessible only to the most brilliant. Cofnas argues that the IQ/religiosity relationships observed in the modern world are largely culturally and historically contingent. Furthermore, the preponderance of high-IQ people who profess varying degrees of atheism might not be all that implicitly irreligious, in light of Cofnas' thesis that atheism itself makes a moral virtue out of non-belief.

The work does have its weaknesses. For example why is Cofnas only concerned with cultural evolution? Human adaptive evolution has undergone massive acceleration over the last 10,000 years; is it not possible that many features of modern religions have in fact co-evolved with their host populations and vice versa? Consideration of this would have been instructive. Despite this shortcoming, the book has tremendous strengths and furthermore deserves to be taken very seriously. The open-minded biosocial scientist should find much that is of interest in this work, and I fully anticipate that many a novel research programme could derive from here.