Christian Moral Argument and Natural Law "Faith and Reason" or "Faith vs. Reason"

 John Kleinsman
Issue 16, August 2005

In America, and now in New Zealand, an increasing number of strong and powerful "religious" voices are emerging in the political arena to debate the moral issues of our time. A number of these Christian voices employ an approach to morality that appeals strongly and at times exclusively to the authority of God in Scripture.

Christian morality must ultimately be able to be grounded in the divinely revealed scriptures. If that were not so it could not claim to be Christian. However, when Christian arguments are presented as grounded only in the authority of scripture, Christians give the impression that the credibility of their teachings depends upon belief in God. Moral duty is then only able to be presented in terms of adhering to certain rules expounded by the Church and supported by scriptures.

Such an approach emphasises faith at the expense of reason. In fact, it effectively pits faith against reason. The role of reason is reduced to the selection and correct application of divinely-revealed rules to various life situations. When Christians emphasise the need to rely totally on faith sources, there is then little or no common ground on which to dialogue with those who do not recognise the authority of the various Christian sources of revelation.

In contrast to the way in which some Christians rely totally on faith based sources for decision making, others locate the origins of moral authority entirely within human experience and human reason. This latter approach originated with certain Greek philosophers who believed that reality was entirely in the "here and now" and that there were no eternal standards or rules set by the gods - or anyone else - to guide us. Ethics, they maintained, consists of making up one's own mind. In contrast to faith based approaches, the decision making process depends and draws entirely on human reason. Reason is emphasised to the exclusion of faith.

While adopting totally opposing stances with respect to the roles faith and reason play in decision making, it is important to note that these two approaches operate out of the same belief that faith and reason are essentially in opposition to, and therefore mutually exclusive of, each other. Neither of these approaches fits comfortably with a Catholic approach to moral decision making.

The Catholic moral tradition emphasises that "faith and reason are like two wings on which the human spirit rises to the contemplation of the truth" (John Paul II, 1998). This approach, grounded in the philosophical thinking of the Greek philosopher Aristotle, integrates both the transcendent and rational dimensions of our human nature: Aristotle believed that ultimate truth originates 'from above', but that people are able to perceive much of what is true through their own perceptions and judgements. Reason and faith are complementary. Reason is a source of moral authority alongside faith.

In the Catholic tradition this moral authority accessible by reason is referred to as 'the natural law written on the hearts of all men and women', a term which draws upon St Paul's letter to the Romans: "When gentiles who have not the law do by nature what the law requires, they are a law to themselves ... They show that what the law requires is written on their hearts." (Rom 2:14-15). In the words of O'Neil and Black (2003, p.163) the natural law constitutes an "interior wisdom that will unfold itself" when we commit ourselves to reflection on human knowledge and experience.

Most importantly, the moral authority accessible by reason constitutes common ground where meaningful dialogue on moral issues can take place between all human beings regardless of religious belief. Natural law represents a meeting place where we can engage in the search for truth with all seekers of the truth.

The Development of Natural Law

It was the brilliant work of the great thirteenth century Dominican, Thomas Aquinas, that first allowed St Paul's insight to become the foundation of a theological framework capable of supporting and shaping a distinctively Catholic approach to morality.

Prior to Aquinas, the Christian view of the world tended to be pessimistic, emphasising the corruption of human nature and consequently the weakness and inadequacy of human powers, including human reason. The corruption of the world, including human death and suffering, it was postulated, was a consequence of human sinfulness in the face of temptation as testified in the story of the "The Fall" (Genesis ch. 3). While belief in the corruption of human nature may have helped medieval people to accept the hardships and miseries of their lives, the logical outcome of this way of thinking is an approach to morality in which there is little or no room for human involvement. In our own time, such a worldview still dominates the thinking of some Christians. Things are right or wrong simply because God (or the Church as God's representative) says so. Because of the corruption of human nature, human reason cannot be trusted. Therefore, ethical standards can only be derived from outside of human nature.

Aquinas readily acknowledges that our human nature has been weakened as a result of our sinful condition and that we are therefore more prone to "deviating" from our deepest inclinations. In spite of that, however, and in opposition to earlier beliefs about the human condition, he argues that human nature has remained fundamentally intact and therefore we can still trust our human reason. Consequently, argued Aquinas, it remains possible for persons to discern key moral inclinations and determine key principles by a process of reason reflecting on human nature.

Accepting this premise of Aquinas means we can postulate a Christian morality that draws on human nature. Now Christians need not rely solely on faith-based insights derived from claims that are grounded in revelation from a source that is "external" to themselves and inaccessible to "non-believers". There can exist a strong positive rational basis for morality that goes hand in hand with, and is further illuminated and clarified by, the insights of revelation. Some of the implications of a Christian approach based on human nature are:

There is a resonance between human reason, human experience, our moral intuition and God's purpose for humankind.

Christian values are eminently Christian because they are in the first place truly human values. Thus, Christian insights into morality confirm what is normatively human rather than originating a different morality.

The humanity of Jesus confirms fundamental human values rather than reconstituting human nature from a corrupt condition.

Natural law enables us to argue for the rightness of particular actions without exclusive recourse to religious insight or motivation.

Natural law validates human experience and knowledge as an authentic path to moral truth

The Church has an obligation to use the findings of the secular sciences as well as drawing on its own theological principles (see Gaudium et Spes n. 44).

Adopting a "natural law" approach to morality means that the Catholic moral tradition can address its teaching to all people of goodwill with a confidence that it is highlighting human truths. The natural law tradition offers a specific pathway to knowing God, a pathway that is marked out by what some have referred to as the "footprints" of God's love and providence imprinted in the beauty and integrity of creation.

The Application of Natural Law

If moral decision making consisted of little more than persons conforming to the appropriate external authority then there would be only very limited space for the use of human reason in deciding what is right from wrong. A natural law approach saves us from this diminution of what is a God given and profoundly human attribute.

Equally important, a natural law approach to morality also enables us to reject the notion that what is right and of value is merely a function of the private feelings and subjective wants of individuals, a position known as 'moral relativism'. Human reason reflecting on human nature provides a definite, even if at times less than explicit, point of reference for moral decision making.

In essence, a moral framework based on natural law emphasises that there is a certain 'given-ness' about human nature and the world in which we live. Thus, 'not everything is up for grabs': being human demands specific ways of behaving. "Human acts have 'built within them,' one might say, a purpose, a goal, an end" (Dunn, 1998, p. 153). Hence, we can talk about actions as being directed towards some general goal, purpose or end. This explains the origins of the very Catholic theological notion that actions have meanings that are inbuilt or 'intrinsic'. This, in turn, leads to a particular understanding of 'human freedom' as living in conformity with the deepest inclinations of our divinely-created human nature. Thus we read, in Veritatis Splendor, that human freedom is not negated by obedience to the divine law; rather it is only through this obedience that it abides in the truth and conforms to human dignity (n.42).

In the history of the Catholic tradition two interpretations of natural law have dominated. The first emphasises human physical and biological nature in determining morality. Those who follow this interpretation find God-given commands in the laws of nature. For them the moral project involves determining the natural 'ends' or functions of things and then acting accordingly. Nature is perceived in a relatively 'static' or closed way. This approach emphasises the order of nature over the order of reason. Its strength is the way it recognises that human effort must take seriously and co-operate with human existence in promoting the well-being of human life. "Part of being human is to have a body whose structure and functions cannot be arbitrarily treated" (Gula, 1989, p. 233). In other words, the 'given-ness' of human nature is clearly recognised within this interpretation.

While it offers clarity, however, the weakness of the first interpretation is a tendency towards rigidity in its interpretation of human action. A narrow focus on the 'goal' or 'ends' of an action can result in a neglect of the 'circumstances' and 'means' together with its true impact on human relationships. It can also mistake the 'givens' of human nature for the whole, or take the fixed character of human existence as closed and beyond the control of human creative development (Gula, 1982, p. 39). The extreme of this view is often termed 'physicalism', because it unduly emphasises the physical aspects of human nature when determining what is right and wrong, to the neglect of other dimensions of the human person. A strongly physicalist approach has little or no room for the distinctively human, creative aspects of moral knowledge and freedom. It is both deterministic and reductionist. Morality is too easily reduced to discovering given patterns in the world, and human freedom reduced to abiding by or violating such patterns.

The second interpretation of natural law emphasises the order of reason over the order of nature. It recognises that our human nature is 'invitation' as well as 'command'; that it is part of our human nature to creatively intervene. This interpretation reflects a more 'dynamic' and 'open' understanding of nature. What is moral involves reflection on the person "integrally and adequately considered", to use a term often quoted by Catholic moral theologians in the post-Vatican II era. The person integrally and adequately considered is the person considered in their totality: physical, emotional, spiritual, mental and relational dimensions. Such an approach requires theology, including moral theology, to enter into dialogue and partnership with the physical and social sciences.

The weakness associated with this view is that, taken to an extreme, it can tend towards a position referred to as 'idealism'. Idealists evaluate the person and human action with little or no reference to the physical structure and functions of the human body or nature in general. The danger of totally disregarding the fixed aspects of human existence and the created order is that important ethical limits may be transgressed in the name of progress.

Richard Gula comments on the distinctions between the two interpretations of natural law:

In a morality based on the order of reason, the human person is not subject to the God-given order of nature in the same way the animals are. The human person does not have to conform to natural patterns as a matter of fate ... The natural order remains an important factor to consider if the human person is to base moral norms on reality. But the natural order is not to be taken as the moral order. The human person can creatively intervene in a reasonable way to direct the order of nature in a way that would be truly human. The 'nature' which reason explores is no longer separated from the total complexity of personal, human reality. (1982, p. 44)

In an age where technological achievements have brought an increased ability to manipulate and shape the world in which we live, some question whether this second interpretation of natural law is perhaps too optimistic in its understanding of human nature, and therefore potentially able to contribute to a growing indulgence in, and blind obsession with, technology. Human confidence in the power and promises of technology, they rightly say, must always be tempered by a humility which recognises that we do not always choose what is good, and that we do not have absolute control.

In fact, understood and applied properly, the natural law approach acts as a deterrent to human arrogance through its insistence on the indelible connectedness that humans have with God, one another and the whole of creation. Reflection on this connection calls us beyond ourselves, beyond human self-absorption to a broader consideration of what is good and its consequent responsibilities. This includes the need to live within limits that will protect and enhance integrity and harmony in all our relationships.

Commenting on the way in which natural law operates, Gerard S. Sloyan (1990, pp. 58-59) writes: "The natural law has sometimes wrongly been proposed as indicating how people must choose in facing quite specific moral dilemmas ... a certitude is assumed concerning the natural law that can only be provided by a long and deep reflection on the implications of the teachings of Jesus and the apostolic age." What this means, in terms of the Catholic-Christian moral tradition, is that natural law functions more as an approach to discovering moral value than as a body of established and specific content. One of the consequences of embracing a more dynamic understanding of 'nature' and 'natural' is that it does become more difficult to 'know' exactly what the natural law proposes.

From a Catholic-Christian perspective the natural law approach may be seen as a "source" of God's revelation alongside of the Scriptures. O'Neil and Black (2003, p.161) note that Natural Law and the Scriptures are complementary modes of assessing God's wisdom and plan for human beings. Both assist us by revealing the image of God, as well as how we are to "touch and live out our God-given inclinations towards what is good" (p. 162). In particular, because of sin, human reason has to struggle to gain moral knowledge. The Scriptures are valuable in revealing in written form what is unwritten, and sometimes difficult to decipher, in our hearts.


In this time when religious voices are reasserting the contribution of the Christian tradition to ethical debates about bioethics, there is the very real danger of increased polarisation between Christians and others. The Catholic natural law tradition provides a way of bringing together the religious and secular voices in so far as it offers a common ground for dialogue and debate.

Recognition of the natural law means that the Catholic-Christian moral tradition can address its teaching to all people of goodwill, and can argue for the rightness or wrongness of particular actions, without having to appeal exclusively to divine revelation or religious authority. The natural law is 'written in the heart' of every person, since it is none other than human reason itself which commands us to do good and counsels us not to sin (VS 44). The Catholic emphasis on natural law legitimises the use of human reasoning when Christians engage in political debates on key moral issues. It is also a statement about how Christians might approach such debates and the sort of language they might employ.

Furthermore, the natural law approach functions to remind us that being human demands specific forms of conduct, and that 'not everything is up for grabs'. By acknowledging our connectedness to all creation as part of God's purposeful design, we are freed from the relentless pursuit of human achievement that obscures our other responsibilities. At a time when research is pushing the boundaries in new ways, the fundamental principles of a natural law approach highlight the nature and limits of human freedom as well as the broad scope of our relational-responsibilities.

At the same time, the natural law tradition allows us to maintain a positive attitude towards human research and achievement based on a positive assessment of the goodness of humankind, its responsibility to exercise reason in the pursuit of well-being for the whole of creation, and its ability to arrive at what is right and wrong by way of reason reflecting on the "natural order".

Richard McBrien (1994, p.17) sums up the Catholic natural law approach well: "Catholicism is, first of all, a way of being human, then a way of being religious, and then a way of being Christian."


Dunn, E. (1998). What is theology? Foundational and moral. Mystic, CT: Twenty-Third Publications.

Gula, R. (1982). What are they saying about moral norms? Ramsey: Paulist Press.

Gula, R. (1989). Reason informed by faith. Mahwah, NJ: Paulist Press.

John Paul II. (1998). Fides et Ratio. Strathfield, NSW: St Pauls Publications.

McBrien, R. (1994). Catholicism. North Blackburn, Victoria: Collins Dove.

O'Neil, K., & Black, P. (2003). The natural law. In The essential moral handbook. Liguori: Liguori Publications.

Sloyan, G. S. (1990). Catholic morality revisited: Origins and contemporary challenges. Mystic: Twenty-Third Publications.


John Kleinsman teaches Moral Theology at the Wellington Catholic Education Centre and is also a part time researcher for The Nathaniel Centre.