The extraordinary and unprofessional reaction to Prof Richard Swinburne's paper at the SCP Midwest conference just over a week ago stimulates me to want to do what a lot of people appear to think should not be done: to engage with the issues Swinburne raises, and the arguments of his paper, philosophically. In a rather brief form, I'm going to do that here.
Swinburne divides moral principles into different categories, which we can call the precepts of Natural Law, and precepts of Divine Law. The latter are only binding because God has commanded them; the former are part of the nature of things, necessary moral truths as they apply to the circumstances of the world we live in. This distinction is common to Aquinas and Scotus, but Scotus puts more of the familiar moral principles of the Decalogue into the category of Divine Law, saying that (a) God had good reason to command what he did, but also that (b) God could have commanded differently, even without changing physical creation. Thus, whereas a Thomist might think that the obligation to honour our parents might work rather differently if human nature was such that we never knew who our parents are (and were born like turtles, out of eggs buried on the beach), a Thomst does not think that God could have told us to ignore our parents given how humans actually grow up. A Scotist thinks that all the precepts of the 'Second Tablet of the Law', from 4th to 10th Commandments (on the Latin/Catholic numbering), could have been different if God had so willed, even given human nature as it is.
Swinburne does not go as far as Scotus in shunting obligations into the category of Divine Commands, but he does want to put a great deal of sexual morality into that category of Divine Commandss, including fornication, contraception, and homosexual relations. He doesn't address the question of universality of these obligation, but it would seem from his discussion that he thinks the obligations are universally applicable despite coming from commands. Scotus did so, saying that all the precepts of 10 Commandments are written on our hearts - although this is logically posterior to God's decision to command them. (Everyone presumably agrees that there are also divine commands which are not universal in application, such as the dietary laws of the Law of Moses, the command to Abraham to go to Canaan, and so on.)
Swinburne then looks for possible reasons why God would have made such commands, saying that if there were no good reasons, this would undermine the claim that God really had commanded them. He looks for such reasons in terms of promoting good things among humans, such as stable family life, optimum conditions for the raising of children, and individuals' happiness.
These are the arguments which caused the controversy, since they necessarily raise disputed issues about whether people would be better off if they don't drift into a homosexual lifestyle and self-understanding. Some of Swinburne's critics seem to regard these arguments as standard Christian arguments for Swinburne's conclusions, but of course they are far from being so. In terms of familiar positions, Swinburne's Scotist position stands between a Protestant rejection of Natural Law (I mean, a rejection by some strands of the Protestant tradition), and a Thomist position. Whereas the former would see no need to look for reasons the divine commands, and focuses solely on evidence for the commands (are they, for example, unambiguously in the Bible?), the latter does not see these kinds of issues as about divine commands, whether well-motivated or arbitrary, and instead seeks an explanation of why morality works as it does by a consideration of human nature.
Swinburne makes a brief consideration of such arguments, but finds them lacking. The example he considers is from the teleology of human sexual organs. As someone more sympathetic to Thomism, I would suggest that this is somewhat superficial argument. It is not just that human sexual organs are (in some sense) designed to work heterosexually, but that there are profound considerations of the meaning of human sexuality which militate in favour of monogamy, and against divorce, adultery, fornication, and homosexual sexual activity as well.
These considerations don't lend themselves to the kind of neat argument Swinburne is trading in, in his paper, but very briefly I will sketch the vision of human sexuality which has emerged from the Catholic tradition, particularly over the last century or so. Sexual union is clearly connected (in terms of tendencies) with procreation, and particular efforts have to be made, in particular cases, to sever that connection. It is also connected with emotional intimacy and attachment. That these things go together makes sense, since small human children are entirely helpless, and it is convenient, to say the least, that the relationship which brought them into being is also a partnership which can provide them with the things they need for their physical and emotional development. Given the emotional and relationship implications of sexual activity for the couple, since sexual intimacy has this connection with emotional intimacy etc., it clearly goes against the grain for sexual intimacy for it to be divorced from monogamous and committed relationships: viz, taken outside marriage.
There is plenty more to be said in the same vein, but I will leave it at that as a sample of the kind of argument which can be made. It may not seem that this kind of argument could furnish us with an efficient and clear-cut argument of the obligations of traditional sexual morality, but that is not, in fact, its job. We know about the obligations of sexual morality from the Natural Law in our hearts, and from Revelation. Whereas Swinburne wanted to see some evidence that these rules would have been chosen by a rational and benevolent God, what I need to see is that they make sense in relation to human nature. In both cases, we're not providing evidence for the precepts, but providing a background for them, and in my case the background is not one even approaching rational justification, but of coherence.
Providing a justification for fundamental moral principles is notoriously difficult, and I hardly think a sensible response is to say that there are no moral principles. Rather, what the Catholic tradition offers is what I would describe as a coherent and satisfying understanding or vision of human nature, human needs and aspirations, and the moral law.
I rather think that I might have got away with an argument along these lines at an SCT meeting, which does not even need to single out homosexuality as an example. The irony is, of course, that it is far more radically opposed to a sexually liberal development than Swinburne's. For on a Swinburnian or Scotist view, it is not so unnatural to wonder if, since it is a matter of Divine Command as opposed (as Swinburne puts it) to the acts in question being 'intrinsically wrong', there might be exceptions, that it might apply to some people at some times and not to others, and that the virtue called for among humans in response is not purity, understood as a sensitivity to the shameful and sordid nature of disordered sexuality, but simply obedience to God. This last point is particularly worrying, since it sets the scene for the observation that we can show obedience by obeying what we merely imagine God commands to be, at which point we are in danger of losing the content of morality altogether: though that would require another argument.