With the falling popularity of the study of academic philosophy, and the preference for academic subjects that are seen to lead more securely to employment, the public discussion of morality has suffered somewhat. When one comes to study academic philosophy, a course in moral philosophy (hopefully several) is usually essential (along with metaphysics, epistemology, and logic). Whilst one can get a smattering of philosophy in other academic subjects, one rarely gets the opportunity to study it in depth unless one undertakes a course in philosophy. That then entails that there is a general lack of recognition in public discussion of philosophical issues, and this particularly is the case with the discussion of moral matters.
In general, there is an awareness of some conclusions that are adopted in moral reasoning, especially with regard to hot button social issues that have their roots in moral philosophy. These conclusions did not come from nowhere, and significant voices in the philosophical tradition have offered reasoning on their behalf. But because of the lack of awareness of moral philosophy and often only a smattering of philosophy from elsewhere, the conclusions are known, but not their means of demonstration (indeed, in my experience of teaching moral philosophy, the very notion of demonstration in moral matters is one that has to be neatly and gently laid out before any exploration of the thinking of a particular philosopher is considered).
Now, moral philosophers are not the only individuals to draw conclusions in moral matters, the Church does so as well. And it is often the case that a moral philosopher draws the same conclusion as the Church, e.g. a number of moral philosophers agree with the Church that murder is wrong. But it is often assumed that a moral position advocated by the Church on some particular issue is one that is defended on the basis of religious belief and not on the basis of natural reason.
However, the latter view is incorrect. The natural law position in morality that is adopted by the Church is not one that depends on revelation for its cogency, nor does one even have to believe in God in order to accept that position. Indeed significant defenders of the natural law have explicitly stated that it can be known by all without recourse to God; so for instance John Finnis in Natural Law and Natural Rights, pp. 48 – 49 states clearly that knowledge of God is not needed for knowledge of the natural law, and indeed he states that part II of his book is an articulation of the natural law without advertence to the existence of God, His nature, or will; Aquinas argues that the principles of the natural law are self-evident, and its further precepts can be elucidated on the basis of rational reflection on human nature (Summa Theologiae, IaIIae, qu. 94, art. 2: http://dhspriory.org/thomas/summa/FS/FS094.html#FSQ94OUTP1).
What the natural law position in morality maintains is that human beings have a nature and given that their actions are rationally willed, in order for humans to flourish as the kind of things they are, humans ought to order their actions in a way consonant with that nature. This is not a moral position that depends on God or revelation for its cogency, but simply on philosophical argumentation, as Finnis, Aquinas and others have articulated it. It stands in contrast to other moral theories, in particular utilitarianism and deontology; and it, like them, is defensible on the basis of natural reason.
The point here is that whilst natural law reasoning may coincide with the Church’s position in moral matters such reasoning does not depend on religious belief. In that case, the conclusions that the Church adopts on the basis of the natural law are not conclusions immune from philosophical discussion and scrutiny or indeed defence (they are not matters of faith), since they have publicly accessible reasons on their behalf. But if they have publicly accessible reasons, then they are as much up for grabs in the public discussion of moral matters as those defended from other moral perspectives.
Dr Gaven Kerr