Sex and Reason 
by Richard Posner.
Harvard, 458 pp., £23.95, May 1992, 0 674 80279 9
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Richard Posner, Federal judge, prolific writer and teacher, is the leading figure in the American ‘law and economics’ movement. That movement has pioneered a new way of explaining Anglo-American law and showing how it could be improved. Its method is to analyse topics – for example, the law of compensation for accidents – in economic terms. So analysed, law for the most part emerges as a set of rules serving rational ends. In accident law, for instance, legal rules are said to achieve the sort of result that would emerge from negotiations at arms’ length between those who cause and those who suffer accidents. But such negotiations would be costly and time-consuming, and accident law spares the parties this cost.

Underlying the analysis is a sort of legal Darwinism. The laws that survive are those that best satisfy preferences because they unconsciously imitate the market. There are of course exceptions to this happy operation of the hidden hand. Pressure groups sometimes distort the rules and there can be historical hangovers. But on the whole whatever is economically optimal is the law. When it is not, economic analysis brings this out and points the way to reform.

Posner has now applied this framework to sex and its regulation in a book as bold and ambitious as anything he has written. It analyses sex as a morally indifferent topic like eating. We are to understand the factors that influence sexual behaviour and then choose dispassionately the best policy for regulating it, just as legislators would choose the best agricultural policy, keeping in mind the warning: ‘in sex as in other areas of life beware of government regulation.’ The first part of the book outlines the history of sexual behaviour along with theories intended to explain it and laws intended to curb it. The second, the core of the work, sets out Posner’s bio-economic explanation of sexuality. The third, more concerned with social and legal policy, is written from a libertarian point of view that owes much to J.S. Mill. It is concerned with the regulation of marriage, contraception, abortion, homosexuality, pornography, rape and non-sexual reproduction. It also traces how the US courts, disregarding market principles, first embraced and then withdrew from the sexual revolution of the Sixties and Seventies. Throughout, Posner summarises empirical research and gives weight to its findings.

He argues that though there are fixed aspects of sexuality that cannot be altered, it is more responsive, by and large, to (non-monetary) costs and benefits than is commonly supposed. The fixed aspects he sees as mainly two. Men have on the whole a greater sex drive than women. All but a few people have a fixed preference either for the other sex or for their own, though if the cost of pursuing that preference is too great they look for a substitute. These fixed points are better explained by (socio )biology than by environment or social pressures. Hence the theory is not just economic but bio-economic. The male bio-strategy is to spread male genes as widely as possible, the female strategy to mate with the male fittest to father and most likely to protect her offspring until maturity. This picture certainly has some plausibility. Its weakness is that no one has so far identified the genes that predispose us to gene-preserving behaviour.

Posner accepts the genetic explanation but thinks it is not essential to his economic analysis. I believe he is mistaken. Unless there is a drive to perpetuate one’s own genes, why are men concerned to bring up their own children rather than fitter and brighter children fathered by someone else? Should there not be a market in which the rich buy up the best children? Why is adoption relatively unusual, and adultery a dominant concern in so many societies? These and other aspects of sexual mores are difficult to explain in purely economic terms and, unless they are treated as irrational, the gene-preserving thesis seems to be called for.

However that may be, Posner argues that sexual behaviour, in contrast with preference, is mostly the outcome of rational choice; sex does not dethrone reason. The balance of private costs and benefits determines the relative frequency of different sexual practices: for many people are prepared if necessary to switch from one form of sex to another. For example, when premarital intercourse is disapproved, petting to orgasm is commoner. When virginity is prized, some teenage girls submit to anal intercourse to preserve it. The proportion of homosexuals who marry is higher the less tolerant the society in which they live. Hence, as the cost of preferred sex rises, substitutes are found. But love is not something for which there is a substitute. Posner defines love as a preoccupation with the unique particulars of another person and holds that its emotional quality cannot be fully explained by economic factors. So biological bonding or imprinting must play a part in it. I would go further. A main point of loving (‘companionate’) marriage or cohabitation is to withdraw from the market and call off the search for sexual partners, at least for the foreseeable future. Monogamous marriage is an anti-competitive, indeed anti-market institution.

What factors influence sexuality? Posner stresses search costs, urbanisation, the ratio of males to females, and above all the economic status of women. Search costs explain why among prostitutes streetwalkers provide the lowest quality of service and call-girls the highest. Urbanisation lowers search costs for sexual minorities like homosexuals, who can find partners more easily in towns, with the result that the number of homosexuals in cities like San Francisco can increase even when the overall population declines. The effective sex ratio – that is, the proportion of available men to women – is also important. Among American blacks between ages 25 and 44 the ratio of available men to women is about 87 to 100. This is said to explain why black men tend to have relatively many sex partners, to be initiated into sex early and to father illegitimate children.

In Posner’s view, however, the main determinant of sexual behaviour and morality is the status of women. What occupations are open to them and how dependent are they on men? In the West, the status of women is said to have gone through three stages. First, as in ancient Greece, a woman’s position was mainly that of a breeder. Apart from occasional copulation, husbands spent little time with their wives; marriage was non-companionate. Substitutes for marital sex such as prostitution, adultery and homosexuality flourished and were tolerated. In a second stage, woman’s role expanded to include that of child-rearer, partner and intimate friend of her husband, so that companionate marriage became the norm. The substitutes, previously tolerated, were then rejected, for when marriage is companionate they threaten the stability of the union and yield less benefit as safety valves. According to Posner this expansion of companionate marriage, accompanied by intolerance of alternatives, prevailed in Western society during the period of Roman Catholic hegemony. The Church’s sexual morality is explained as the outcome of an attempt to improve the status of women – a generous interpretation. Finally, when most women find well-paid employment outside the family, as in contemporary Sweden, marriage remains companionate so far as it survives, but there are fewer marriages and the alternatives are more readily tolerated. If the state also subsidises one-parent families (‘another link between socialism and promiscuity’), men become relatively dispensable, all the more so if artificial insemination spreads. The transition from stage two to stage three can be explained by reduced child and childbirth mortality, improved contraception, the spread of light industry and labour-saving devices in the home. In the first and third stages men enjoy sexual licence, but women do so only in the third. But the third stage prejudices those women who prefer a traditional family role because men have less incentive to look after them if the employment market or the state will do so instead.

All this is admittedly schematic. Different ‘stages’ can co-exist. Evolution is not always progress. Alternative explanations sometimes spring to mind. Nevertheless the analysis is powerful, and Posner backs it up with some surprising predictions, which research might falsity, based on the factors that he claims influence sexual behaviour. For example, when adjustment is made for the general level of criminality, black men are said to be less likely to commit rape or abuse children than white men. Effeminate, handsome and macho heterosexual men have more opportunistic homosexual experience than other heterosexual men. The incidence of adultery relative to fornication has declined over time. The percentage of homosexual Roman Catholic priests has risen since the Middle Ages. The reasons for these conclusions are too intricate to set out in a review: those who want to know why will have to read the book. But the examples convey an idea of its verve and audacity.

Of course there are reservations. Not that the economic analysis of sex is misplaced. It is true that buying and selling do not play much part in sex and reproduction. The main exceptions are prostitution and payments to adopt children (so-called baby sales) – the last being an area in which Posner is prepared to advocate a market in parental rights provided those traded are very young children who have not yet bonded. But non-monetary costs and benefits do shape institutions like marriage and cohabitation, especially when partners are freely chosen, and they go a long way in explaining resort to substitutes. The main merit of Posner’s book is to have explained this with balance and sobriety, paying due attention to research findings. It is true that at times his tough language jars, as it is perhaps meant to: infanticide should be ‘viewed as a method of family planning”; the ‘terms of trade’ between wives and husbands may turn in favour of wives. But his actual recommendations for reform are not surprising. They are mostly of the sort one would expect from an American libertarian: repeal of the laws against adult homosexuality, making marital rape a crime, tolerance of pornography, particularly of serious erotic art, fence-sitting (at first sight unexpected) in the abortion controversy.

Economic analysis has its limitations, however. It is bad at taking account of collective goods, like our interest in the social and physical environment. It is legitimate for a society to take steps to preserve a valuable and valued way of life – for example, by limiting immigration. There is nothing inherently chauvinist or racist about such a policy, though of course it can be carried out in a discriminatory way. It must be equally legitimate to frame laws so as to encourage healthy social institutions like companionate marriage and cohabitation. Posner probably agrees with this, for he criticises Swedish welfare legislation for favouring one-parent over two-parent families. But his mode of analysis marginalises collective interests. Pornography affords an example. The discussion of its benefits and costs concentrates on benefits and costs to individuals, research into which is inconclusive. But what about the atmosphere created by the spread of pornography? It is not irrational to think that an environment with less of it would be healthier and more relaxed, especially for women, while granting that, given modern technology and the financial interests of publishers (and Posner rather neglects financial pressure groups), the law can perhaps do little to reduce it.

Posner does not give collective interests enough weight. But his stress on the need to find facts before framing policy is valuable even when collective goods are in question. Should the unenforced laws that still make adult homosexuality a crime in many American States be repealed? The weight of research shows that homosexual preference is fixed from birth or early youth, and that, contrary to the assertions of the homosexual lobby, the percentage of people with a homosexual preference, as opposed to opportunistic homosexuals, is not more than 4 per cent for men and 1 per cent for women. If correct, this shows that decriminalisation will not transform the social scene more than would admitting a small percentage of immigrants, though in each case a subculture will emerge, or emerge more strongly than before. One possible objection to the libertarian argument for repeal therefore falls away. Nor are unenforced laws a matter of indifference, since they can have unexpected effects. For example, the Connecticut law banning contraception did not stop contraception, but it closed down birth-control clinics in that State between 1940 and 1965, when the American Supreme Court held it unconstitutional.

More serious is Posner’s view of morality. Sex cannot really be as morally indifferent as eating. Morality concerns the impact, both individual and collective, of our behaviour on other people and animals; and the reasons, deriving from this impact, for accepting restrictions on what we do. Eating has an impact on animals killed to be eaten, but otherwise hardly raises moral issues. Sex is different because sexual behaviour impinges on our sexual partners and on their partners, on children, families, the social environment and future generations. Posner has the laudable aim of helping people to learn the facts about sexual behaviour and think calmly about how and to what extent to regulate it. But his pursuit of this aim is vitiated by his belief that there is a gulf between rational and moral thinking. He follows Fitzjames Stephen and Patrick Devlin in equating disgust or aversion to a practice with its being immoral. He thinks that morality, so defined, must be respected even when it runs counter to economic analysis. We then end up with a society regulated partly by economic reason and partly by moral unreason.

Why confine the scope of reason in this way? The disgusting is not automatically immoral. Is it immoral to urinate in the washbasin? If intercourse with animals is wrong, it is because there is a reason why it is wrong: namely, that it degrades animals. To equate the disgusting and the immoral undermines morality, for if morality is just a matter of strong likes and dislikes there is no reason, except hypocrisy, to respect it. Of course Posner knows perfectly well that economic analysis is not morally indifferent. At times he writes as a utilitarian, at others as a libertarian. When he discusses ‘externalities’ (two people making arrangements that impose unwanted costs on third parties), he appreciates that they raise moral issues. So his economic analysis has a moral basis, but one which leaves out important values. He sees this, but not how to escape from the dilemma. Thus, he admits that economic theory cannot solve the abortion controversy because it has nothing to say about the community whose welfare is, on a utilitarian view, to be maximised. Does that community include foetuses? There is no rational way of deciding. ‘A tiebreaker is needed.’ Isn’t the tiebreaker the legislature or court doing its best to find a solution both morally defensible and workable in practice?

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