Modern liberalism has difficulty finding a place for the societal good of such normative structures as the family, because of its commitment to neutrality between life-shaping values. At most it can register and even celebrate convergence in evaluations, seeing in this happy coincidence possibilities for establishing and extending a social consensus. However, the liberal idea of social members as free and equal persons remains individualistic: the good of persons that results from their participation in social orders regulated by this notion of political justice is a private one. This fact is sometimes overlooked on account of the regulated order being a public good or shared benefit; but therein lies a lesson: public good does not equal common good or a common set of values.

I want to consider further the issue of marriage and the family mindful of the facts that, as Clegg observes, this form of association is changing and that it has become a subject of much public discussion and some significant dispute. Of course, not all marriages lead to or involve the having and rearing of children or the care of parents, and not all families are joined by bonds of matrimony. Nonetheless there are strong connections between marriage and family life. Common experience and an increasing body of empirical research tells us that it matters that children are raised in a family context, and that it is best for a child if this consists of a mother and father, ideally supplemented by male and female of older generations and by siblings. Evidently these considerations bear on the issue of same-sex and and polyamorous households and so connect with current debates about the legal recognition of sexual partnerships.

In the 1980s and 1990s the policy issues that seemed most pressing upon family life were ones concerning divorce and children's rights (also certain economic measures to do with welfare benefits). More recently the strongest challenge is that posed by "alternative sexual lifestyles". Along with abortion, sexuality has become one of the main issues of contention between traditional morality and politics, and the moral and social philosophy of liberal pluralism. Although a range of matters is in contention, the most prominent is the issue of homosexual practice and its recognition by the state. It is only relatively recently that homosexual relations have been decriminalised in many Western societies: 1967 in England and Wales, 1969 in Canada, 1980 in Scotland, 1982 in Northern Ireland, 1986 in New Zealand, and in some they are still illegal. Yet in many of the states where homosexual activity was once prohibited, legal rights are now bestowed on homosexual partners and there are increasingly determined calls to extend the institution of marriage to them, which several legislatures have done, including Belgium, Canada, Portugal, Spain and Sweden. 

For those liberals who uphold the moral neutrality of the state this latter prospect can be perplexing. For on the one hand while they do not believe that it is for the state to proscribe sexual practice on moral grounds, nor do they believe that it should endorse, let alone prescribe, forms of sexual union as expressions of moral values. Yet this latter is precisely the basis on which some gay, lesbian and transgendered activists seek the extension of marriage to homosexual and transgendered partners. In this respect at least they share with the traditional defenders of heterosexual marriage a common belief in the value of publicly recognised partnerships.