Aquinas’ approach to moral decision-making goes well beyond basic Natural Moral Law. Influenced by Aristotle, Aquinas’ ethic is sophisticated and includes a virtue ethic and theory of conscience as well as a normative approach for deciding on what is right and what is wrong. As such, Aquinas’ approach to moral decision-making is very useful.

Firstly, because Aquinas’ approach is rooted in Aristotelian Ethics it is supported by rational arguments and is consistent. Like Aristotle, Aquinas observed human beings and saw that people tend to flourish and then defined his primary precepts or basic human goods in relation to human flourishing, in terms of what supports that end. People flourish when they enjoy long life, live peaceably in society, when they have children and teach them and when they learn and praise God. Aquinas reasoned that actions which contribute to one or more of these goods and so to flourishing are right and actions which inhibit one or more of these ends are wrong. The secondary precepts of Aquinas’ natural law are, therefore, easily deduced from the primary precepts, providing a useful source of moral guidance and justification for rules, which are more practical and useful than expecting people to make decisions situationally. Nevertheless, Aquinas recognised that everyday decision-making is not only about following rules like do not murder… flourishing involves developing positive habits (virtues) and avoiding vices. Aquinas agreed with Aristotle (and modern virtue ethicists also agree) that habits, as well as consideration of somebody’s whole character rather than only individual actions, are useful in moral decision-making. This focus on virtue, habits and character has been overlooked by Roman Catholic Ethics in their application of Aquinas’ approach, leading to what Fletcher criticised as a legalistic approach, meaning that Aquinas’ approach is more useful than Roman Catholic applications of his thinking today. In addition, Aquinas argued that people should act autonomously, following their God-given desire to do good and avoid evil and what they have learned from practical reason (synderesis) to act on what their conscience suggests as a moral duty. This focus on individual autonomy and conscience also makes Aquinas’ moral philosophy more useful than Roman catholic applications of it, which often seem to support blind obedience. As Kant, William Temple and Bonhoeffer would point out, “on freedom our moral life depends.” If we don’t make decisions for ourselves, but defer to authority and practice blind obedience then we will not flourish as a person even if strictly speaking we do the right thing. This shows that Aquinas’ approach to moral decision-making is a useful one and more useful than Roman Catholic applications of it today.

Secondly, Aquinas approach to moral decision-making is useful because it is rooted in and is consistent with the Bible and Christian faith. For Aquinas, the reason people want to flourish and act to support human flourishing is because God created them that way. In Genesis 1, God creates people good and orders them to “be fruitful and increase in number…” showing that flourishing and following the primary precepts of living long, procreating etc. are in fact doing God’s will. Whereas Aristotle’s ethic is avowedly non-religious, Aquinas’ ethic is so acceptable to Christians – still the largest group of religious believers in the world – that it was adopted as the basis for Roman Catholic ethics at the Council of Trent. Today, Roman Catholic Ethics stands on the three legs of Scripture, Tradition and Reason as authorities… meaning that it is not subject to Biblical literalism as Protestant ethics is, and neither is it changeable, inconsistent or unreasonably conservative. Aquinas showed the Church the way to achieve this, which has contributed significantly to the Church’s survival and growth through centuries of change and new moral challenges. Clearly, Roman Catholic Ethics today has rightly been criticised for being Legalistic, inflexible and encouraging blind obedience, but other scholars have returned to Aquinas for inspiration in showing how this is a selective and not a necessary application of His original ethic. For example, John Finnis roots his ethic in Aquinas, providing an approach which encourages both autonomy and acting according to Church teachings. Bernard Hoose also roots his proportionalism in Aquinas, and shows that it can be applied to support breaking even the strongest prohibitions in extreme situations, avoiding the criticism of being inflexible. Again, the fact that Aquinas’ approach to moral decision-making is so useful to Christians shows that it is a useful approach.

On the other hand, Aquinas’ approach to decision making has been widely criticised. Natural Law relies on moving from observations of the natural world to claims about how we ought to behave. Hume pointed out that moving from an is to an ought needs significant justification, because how things are is not a good guide for how things necessarily ought to be. Further, GE Moore rejected Natural Law because it depends on what he called the Naturalistic Fallacy, suggesting that people should do what they naturally do. Nevertheless, John Finnis has rejected this criticism of Aquinas’ Natural Law, pointing out that Aquinas can be interpreted as being an intuitionist, seeing that the desire to do good and avoid evil and the primary precepts appeal directly to reason before and without experience. This shows that the metaethical critique of Hume and Moore is not conclusive. Aquinas’ virtue ethic has also been criticised by Kantians for encouraging people to develop habits rather than making rational decisions each time. For Kant a “good will” can only be good by acting freely and rationally, being fully human, in every decision, acting out of habit would make a will bad, even if it did the “right” thing as a result. Nevertheless, Finnis again shows that Aquinas’ concern for virtue and character can be brought together with his natural law by making “practical reasonableness” one of the basic human goods. Rather than separating natural law and virtue ethics, Finnis sees being free and rational as the single human habit on which being good – whether in individual actions or character-traits – depends. Again, this shows that Aquinas’ approach to decision-making can be made to evade criticisms and can still be useful. Finally, Aquinas has been criticised for having a over-complicated and speculative account of conscience which is likely to lead people into error, following the guidance of their own imperfect synderesis rather than the infallible teachings of the Church. It is true that Aquinas’ theory of conscience is not based on science, but then again, neither really is Freud’s! Aquinas’ understanding of conscience does do justice to human experience, explaining why we naturally want to do good and avoid evil but also why we sometimes struggle to know how and feel drawn to break moral norms. It is also consistent with other theological accounts of conscience, such as that of Newman, and with Philosophical accounts as well, such as Kant. In this way, Aquinas’ use of conscience within his approach to moral decision-making is not a weakness and his approach is still useful.

In conclusion, Aquinas’ approach to moral decision-making remains useful, both to Christians and more widely. While the application of Aquinas’ approach by the Roman Catholic Church has led Aquinas’ approach to be treated with scepticism, it merits serious consideration both by Catholics and by everybody else.