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"It is through conscience that human beings see and recognize the demands of the divine law. They are bound to follow their conscience faithfully in everything they do."
Religious Liberty, no 2.

Natural law

By Gerard J. Hughes .
Chapter 2 from
Christian Ethics, An Introduction.
Edited by Bernard Hoose,
Published by Cassell, 1998 and reproduced here
wiith the usual permissions

Gerard J. HughesWhen it is used in connection with ethics, or with Christian ethics, the phrase 'natural law' in its broadest sense refers to the view that morality derives from the nature of human beings. The controversies surrounding this view can be traced, again in broad outline, to one of two sources, trhe first concerned more with method, and the second more with content. They might be summarized roughly as follows

(1) Different views about the use of reason to discover God's designs human beings.

(2) Different accounts of what human nature is, and about how, and indeed whether, there is any way of deriving morality from such account.

In a broad sense it would be fair to say that almost all the classic Western philosophers, from Aristotle to Bentham, tried in some way show that morality had its basis in human nature. Many of them would contrast morality as derived from human nature itself with the moral customs and legislation of particular groups of human beings, and would on occasion appeal to the natural law as a basis for assessing and on occasions rejecting the legitimacy of particular customs or laws. In own day, documents like the United Nations Declaration on Human Rights propose a set of rights which belong to human beings because what human beings are, and which ought to be respected for that reason. It can be appealed to precisely to challenge the customs or legislation particular countries. The many difficulties encountered in attempting to elaborate what the natural law is have at least until comparatively recent times not deterred philosophers from holding that some such basis for morality there must be. However, the difficulties are serious enough. I shall in this chapter try to outline and assess them by elaborating on the two types of issue mentioned above.

Human nature and God's design

Human nature as an embodiment of God's design

A comparatively uncomplicated view of human nature which a religious believer could hold is that human nature, as we find it, reflects the wisdom and goodness of the creator God. To the extent that we can understand ourselves, to that extent we can understand God's designs in creating us as we are, just as to the extent that we can understand anything else in creation we can to that extent understand how the creator God intended things to be. In principle, then, and leaving aside for the moment any of the difficulties under (2) above, if we can show how to base morality upon human nature, we will come to understand how God intended us to live. Thomas Aquinas is typical of many Christian writers who accepted this position. His term for God's creative designs was the 'eternal law'; and under that term he included God's designs for the non-human parts of creation as well as the human. The non-human parts of creation reflect the eternal law in a deterministic way: they inevitably behave according to the natures they have. The laws of nature, discovered by scientists, describe the behaviour of things. Aquinas is willing to use the terminology of law and obedience even here, and to say that these parts of creation obey the laws of their natures; but 'obey' here is a metaphorical expression. The laws of physics do not require things to behave in a particular way, they simply describe how they by nature do behave. This is true, in part, also of human beings, since we are also part of the natural world; our bodies behave according to the laws of physics and chemistry like any other bodies in the universe. Aquinas contrasts this way of embodying God's designs with the specifically human way in which we might do so. Unlike rocks or trees, human beings can come to understand the kinds of beings they are, and are free to live in a way which corresponds to that understanding, or to refuse to do so. We are not naturally determined to exhibit God's designs in our lives. Of course, our understanding of ourselves and hence of how we should live is in all probability limited. In this respect it is no different from our understanding of physics or astronomy or any of the other natural sciences. Still, as with the other sciences, there is no limit in principle to how much we can learn; and the more we do learn, the more God's design for us will become clear. In the eyes of some theologians, however, this comparatively simple view is altogether too simple. In particular, it fails to take into account the theological doctrine of the Fall. They would argue that human nature, as we know it now, is very far indeed from expressing the way God intended us to be; it has been distorted by our own wrongdoing at every period in human history. Theologians did, and to some extent still do, differ considerably in their estimate of the extent of this moral distortion of human nature. Views range widely. Some would argue that while indeed we are weakened, both in our minds and in our constancy in seeking the good, this weakness is not such as to invalidate the view that, reflecting on ourselves even as we are, we can still see how God intends us to live. The most they would concede is that this reflection might be more difficult than it ideally should have been. At the other extreme, it has been held that we are so weakened that, left to our own devices, we are simply not capable of seeing in ourselves anything but our own distortions; there is therefore no secure way in which reflection on ourselves as we are can tell us anything about how God intends us to be.

To give a proper account of these differences would take us too far into issues which are more properly the concern of systematic theology. But perhaps some brief points can be made which might at least help to pinpoint where the real disagreements lie. A convenient place to start is with the famous slogan of the sixteenth-century reformers, sola fide, sola gratia, sola Scriptura, 'only by faith, only by grace, only from Scripture'. It is the last two of these which are of immediate importance. Going back to the time of Augustine, there was a controversy in the Christian churches about the need for divine assistance, 'grace', to enable us to know what God's will is and to follow it. Pelagius and his followers were thought to deny this, and to say that with our own unaided powers we could do a great deal; and this view (whether Pelagius really did hold it or not) was rejected as heretical. It remains a further, and separate question, to whom and how God's grace becomes available. Is God's grace in fact available to everyone who sincerely seeks God, whether they are Christian believers or not? It is possible to hold that God's grace will always assist the sincere moral reflections of human beings, so that in practice human reason need never be unaided human reason, while still maintaining that the natural law can be known without appeal to the specifically Christian revelation in Jesus, as interpreted in the biblical and later Christian tradition. One might, therefore, accept sola gratia, without accepting sola Scriptura. Those theologians who insist upon sola Scriptura will generally reject the usefulness of a natural law approach to Christian ethics.

In any event, theologians have often found it difficult to be consistent, either in their proclaimed trust in, or in their clear distrust of, the use of reason in ethics. Reformed theologians like Karl Barth, despite their rejection of a natural law approach, have in practice used reason to reflect on human nature as we know it, partly in order to interpret Scripture itself, and partly to supplement its moral teachings to deal with issues which are not mentioned in Scripture at all. At the other end of the theological spectrum, some Catholic theologians, despite their theoretical insistence that we can in principle discover God's designs by using our reason to reflect upon human nature, have in practice shown a good deal of distrust for such purely philosophical reflections, and have insisted that they be corrected or supplemented by revelation, or by the Church as the proper interpreter of revelation.

Natural law as a counter to theologically based ethics

From the time of the Enlightenment until our own day, people have been impressed with the progress of the natural sciences. In particular, the methods of the natural sciences seem to have proved themselves beyond all doubt, simply by being so helpful in enabling us to understand, and to some extent therefore to control, the world in which we live. For this reason, it became fashionable to contrast the steady progress of science with the unsolved disputes between divided theologians, and to suggest that if human nature were studied scientifically, discoveries about human morality would rest on a more secure basis than they ever could by being left to theologians and divines. In consequence, proponents of what was at least in some sense a natural law theory of ethics saw themselves as for the first time providing a good scientific grounding for morality, a grounding which hitherto had been sadly lacking. Along with Aristotelian science, now regarded as totally discredited both in its conclusions and in its method, Aristotelian ethics, whether in its original form, or in the medieval version of it adopted by Aquinas, was also thought ripe for replacement. Strong elements of this approach are to be found in thinkers as different in many other respects as Thomas Hobbes, David Hume, Immanuel Kant and Jeremy Bentham.

Not, indeed, that the ethical conclusions reached by most of these writers were either surprising or radical. By and large, they endorsed the moral codes of their day. Hobbes said that the problem with earlier writers (among whom he very likely had Aristotle in mind) was that they had indeed given lists of moral virtues, but they had totally failed to explain why these character traits should be thought of as virtues. He therefore set out to show how those same virtues could be derived from a secure basis in physics, and human psychology. Hume, too, explicitly tried to show how it is that ethics can be explained by studying human nature, using the methods of the new sciences. His intention was not to offer revolutionary moral views, but to explain how ethics arises from the workings of human nature. Kant endeavoured to provide ethics with the same kind of philosophical justification as he believed he had provided for the natural sciences. It was not so much the conclusions of traditional ethics which these writers called in question, as the lack of any scientifically justifiable basis. Traditional ethics (as it so happened, largely Christian ethics) was rejected as methodologically unsound. Somewhat in contrast, Jeremy Bentham was much more of a social reformer, as were the utilitarians who followed him. They tried to give unarguable reasons for criticizing those who resisted the reforms which they saw as absolutely necessary in the wake of the industrial and political upheavals of the late eighteenth century. Once again, they tried to achieve this by providing ethics with a scientific foundation which could not be gainsaid. John Stuart Mill, a disciple of Bentham, once said that Bentham was not a great innovator in moral philosophy, but he was a great innovator in philosophical method in ethics.

In various ways there has long been a tension between those philosophers who insist (sometimes with hostile intent, sometimes not) on using human reason to reach conclusions about God and about how we should live, and those who insist on the primacy of revelation and theology. This tension has been evident in many areas, from astronomy to the origins of the world, from the theory of evolution to ethics. Now, truth is one, and the truths established by rational means cannot conflict with God's revelation. In trying to resolve discrepancies between what we believe we have established on philosophical or scientific grounds and what we believe to be the correct interpretation of God's revelation, we have to admit in advance that in principle either or both sets of beliefs may be mistaken. Human reasoning can go wrong and often does; and the Christian community has not infrequently misinterpreted God's revelation in Christ and in the Scriptures. It is rationally indefensible to assume in advance of any inquiry either that there can be no such thing as divine revelation, or that it can have nothing to teach us about ethics; and it is theologically irresponsible to insist on a particular interpretation of God's revelation which cannot be shown to be rationally defensible and consistent with all that we have learnt by other means about ourselves and our world.

Human nature and the basis of ethics

Human nature has been understood in many different ways. In the opinion of Plato, of Augustine and of Kant, human reason, or the human rational soul, was regarded as defining what a human being essentially was, and the human body was regarded either as an unavoidable hindrance, or at least as an irrelevance so far as the moral self was concerned. The British philosophers from Hobbes to Mill believed that ethics depended on human some very simple desire(s) - for pleasure, or self-preservation, or power. All these views are still in varying degrees influential. But in fact the most enduring version of the natural law tradition in Christian thought draws its inspiration from Aristotle as interpreted by Thomas Aquinas. Aristotle rejected the body/soul dualism of Plato in favour of a much more unified view of the human self in which physical and mental powers were more closely inter-related. Human beings are animals who can think. As a result, his ethical views stressed the importance of the emotions (which for Plato, and later for Kant, were simply to be tamed or excluded as motives in ethics). Aristotle would also have regarded the 'scientific' psychology of Hobbes or Hume or Bentham as grossly over-simplified. Human needs and desires are irreducibly complex; and while, doubtless, simplicity is indeed a desirable feature of any theory, whether in the human or in the natural sciences, it must not be bought at the price of distorting the facts. It was in all essentials this Aristotelian view which Aquinas adopted, modifying it only to the extent that he was prepared to supplement it with specifically Christian beliefs about the law of the Holy Spirit written in our hearts, and to adapt the Aristotelian notion of a fulfilled life (eudaimonia) to accommodate the Christian belief in the vision of God in heaven.

To understand the predominant Christian view of the natural law, then, one must begin with what has become known as the 'Function Argument' which Aristotle sets out in his Nicomachean Ethics, Book 1, ch. 7. Of course, to understand it fully one has to read it against the background of Aristotle's philosophy as a whole. Here, then, is a commentary on its main elements.

Aristotle held that human beings have a variety of activities which by nature they are capable of performing: growing, reproducing, sensing, feeling emotions, thinking and choosing. Each of these can be performed well or badly, and each one in the list depends upon the preceding ones, in the sense that for the 'higher' activities the required bodily infra­structures have to be in place and properly functioning. Some of these are activities we share with other animals, others are characteristically human. He believes that for a human being to live a fulfilled life, all these activities must be functioning well. Though a fulfilled life will, of course, involve keeping healthy, and sleeping, and digesting and so on, what makes it fulfilling are not these background activities, but the activities of intellectual understanding and contributing to society. Human beings are thinking social animals.

All thinking involves an insight into particular cases in the light of which we can formulate general laws. In scientific theories, we can then use these general laws to explain individual events. This is how Aristotle understands reason to function in its purely speculative activities, as we try to understand the world around us, and God. But, as he somewhat ruefully says, a life devoted entirely to such speculative activity is 'too high for man'. But something of this vision of the grasp of all truth being the pinnacle of human fulfilment was taken over by Aquinas and interpreted in terms of the Christian doctrine of the beatific vision. In practice, though, Aristotle accepted that human beings must also live a life of contribution to the community; and this requires us to turn our reason to practical decisions.

We will, if we have been well brought up, have already grasped connections between actions which have been described to us as wrong, or as cowardly, or dishonest, generous or mean. We can formulate general rules about what it takes to be brave, or dishonest, or generous. But, says Aristotle, practical wisdom (we might say, 'moral discernment'; his term is phronesis) requires that we be able to read individual situations in a morally correct way, since morality requires us to make particular decisions. We already have at our disposal many moral concepts which we have learnt to use: but we have simply to see what is required of us here and now: whether, for example, to say 'That's very good' to someone would be a lie, or a proper piece of encouragement, or a raising of false expectations of progress. There are no rules which will tell us how to do this, no arguments which can be used: what we need is long experience of life, and emotional balance.

Aristotle points out that being liable to over-react, or under-react, emotionally does not destroy someone's ability to do theoretical mathematics; but, in his view, it certainly does undermine one's judgement in making moral decisions. To make good moral decisions, and to be able also to trust our moral insight, we need to come to individual decisions with a solid emotional balance; and that, in turn, requires that our emotional responses have been properly trained. (Here, the contrast with Plato is evident.) To have appropriate emotional responses is to have all the moral virtues.

All this Aquinas takes over. He speaks, as does Aristotle, of the first principles of practical reasoning. What are these? They include two different types of principle: (1) purely formal principles: The most basic of these is the principle of Non-contradiction, which should govern all our reasoning, whether speculative or practical: another purely formal principle is 'Good is to be done and evil avoided', which should govern all practical reasoning. These formal principles as it were set the ground rules for how we should think, in science or in ethics; but they do not in themselves tell us what to think. (2) Other 'first principles' have substantive content. In science, they contain fundamental truths about the natures of things in the physical world; and in ethics, such truths as that life and health are good things, as are education, and honesty, and the virtues generally. He also points out that there are many other moredetailed good things'; examples might be open heart surgery, or nursery schools, or confidentiality, or giving to Oxfam. I have chosen these more specific examples as indicative of ways in which we might seek to promote health, or education, or honesty; but Aquinas points out that these more detailed good things are less clear, and less likely to be truly good in all cases, than the more fundamental ones. He, like Aristotle, does not believe that it is possible in ethics to have anything like the precision one might hope for in the natural sciences. And, just as Aristotle appeals in the en to the insight of the person of practical wisdom and emotional balance, so Aquinas stresses the importance of prudentia (his translation of Aristotle's phronesis), which presupposes fortitude and temperance (the balanced emotional response in the areas of aggression and desire).

What neither Aristotle nor Aquinas believes is that from general mora principles we can simply deduce what we ought to do in individual cases. Part of the reason for this is that there is no way of logically deducing the desirability of open heart surgery from the desirability of health, even though the desirability of open heart surgery may be based upon the desirability of health; and, second, though it is true in all cases that health is a good thing, it is not true that open heart surgery will be a good thing in every case. There is no substitute for seeing, in the circumstances of each situation, what is to be done. Of course, one can explain one's decision afterwards, by stating the good ends at which it was aimed. But that does not in itself justify one's decision. For example, I could decide to say 'That's very good!' to someone, and explain that by saying that they needed encouragement at this point; but equally, I could decide to say 'Really, that could be a lot better' by saying that what was required was honest criticism. Each decision can thus be explained in terms of the good at which it aimed. But the explanation does nothing to justify one decision rather than the other. Aristotle and Aquinas agree that the person of practical wisdom will just have to see what is to be said to the person; and that 'seeing' cannot be further justified by argument. And were someone to object that saying 'Well done!' was simply a lie, and therefore wrong, the reply would be that in the circumstances, it was an act of kindness, not a lie, and if the critic does not see that then he is simply lacking in practical wisdom.

As will be seen, then, Aquinas's view of natural law combines the conviction that what one ought to do is based upon what is good for human beings given how human nature functions, with a remarkably flexible account of what people ought to do in practice. Consistency requires that we treat similar situations in the same way, and the injunction that we should do good and avoid evil requires that in explaining our choices we have to be able to explain the good at which we were aiming. But neither these requirements, nor any of the more specific statements about what things are good for human beings, will of themselves settle how particular decisions have to be taken.

Therein lies both the strength and the weakness of natural law theories, whether those of Aquinas and Aristotle, or the views of such writers as Kant, or Hobbes, Hume and Bentham.

Their strength lies in the basic contention which is common to them all, that ethics ought to be firmly rooted in what human beings are like, and how they interact with their various environments. Although in more recent times views of ethics have been propounded which are explicitly value-neutral, it is perhaps more generally accepted that we cannot just decide what we will count as a human good. What is good for us depends upon our natures, not upon our decisions. And, in theological terms, it seems more consonant with the wisdom of God that he wills us to be fulfilled individuals, fulfilled according to the nature with which we have been created. Moreover, natural law theories have always been committed to the view that there is room in ethics for truth and falsity: we can be mistaken, less easily with regard to very general aims like health, or education, or freedom, but more and more easily in more specific types of case, about what genuinely is fulfilling for ourselves or others. We can get things right, but also get things wrong. We have to discover what truly fulfils a person, we cannot simply decide what we will count as fulfilment. Moreover, these theories all insist on the connection between ethics and the human sciences. Aristotle and Aquinas were no exceptions to this, despite their lack of modern scientific knowledge, and despite the strictures of the Enlightenment critics. What has changed is the conception of scientific method, rather than the basic view that in order to understand ethics, let alone to make good ethical decisions, one has to understand human beings in a scientific way. The more we can understand medicine, or psychology, or sociology, the better placed we will be to understand what we are actually doing to ourselves and one another, and hence the better placed to see what we ought to be doing.

Their weakness, if weakness it is, lies in the difficulty of relating complex decisions to basic principles. For example, whether to spend more money on the health service than on education, or whether to insist on doctor—patient confidentiality where minors are concerned, or whether to allow genetic research, and if so under what limitations. These decisions obviously affect different people, for good and for ill, and at least often make it only too clear that it is just not possible to achieve everything we would wish all the time. Philosophers and theologians have wrestled with these issues, and have tried to give theoretically consistent accounts of why they advocate looking at them one way rather than in some other, as indeed they are intellectually bound to do. It has often been said, with some justice, that most moral philosophers and theologians, including those who are sympathetic to this overall approach, in the end are unwilling to depart very far from the received wisdom of the society or Church with which they identify, and that their theoretical accounts are tailored to defend the status quo. Aristotle, as is well known, failed to see anything wrong with slavery, or with allotting a subordinate place in society to women. Hobbes seems to us altogether too wedded to an absolutist form of government, Bentham and Mill not sufficiently sensitive to the fact that some people's desires might be morally perverse. Though in principle natural law theories are geared to the critical assessment of the received moral wisdom of any particular time or place, they have in practice not always succeeded in providing such criticism, precisely because the very flexibility of the theory can make it hard to demonstrate that a mistake is being made in its application. We tend to identify human fulfilment with what we have learnt is human fulfilment, for men, or women, Europeans or Amazonian villagers. Gross moral mistakes can be identified readily enough; but even if they can easily be spotted, there is still much room, perhaps too much room, for more detailed, but no less important disagreement.

The temptation at this point is to use authority rather than a painstaking return to fundamental methodology to achieve greater consensus. Appeal can be made to theology, or to long-standing custom, or to the impossibility of stepping outside the moral consensus in which one has been brought up, a consensus which must therefore in its broader outlines be allowed to go unchallenged. There are many authorities to which appeal can and has been made, some with more claim to credibility than others. The mistake is to use the appeal to authority rather than reasoned argument, or to insist on the total primacy of what we take to be reasoned argument while paying no heed whatever to the accumulated wisdom of our own and past generations.

Select bibliography

Thomas Aquinas, Summa Theologiae, I-II, qq. 91-94; II-II, qq. 47-52.
Karl Barth, Church Dogmatics, II, 2 (Edinburgh: T. & T. Clark, 1957).
John Finnis, Natural Law and Natural Rights (Oxford: Oxford University Press, 1980).
Paul Helm (ed.), Divine Commands and Morality (Oxford: Oxford University Press, 1981).
Richard Kraut, Aristotle on the Human Good (Princeton: Princeton University Press, 1989).