The Moral Argument

Morality concerns what is right or wrong in our actions. It asks what we should do and what we should avoid. It comes into play when we distinguish a just action from an unjust one. Helping a person in danger and deliberately harming them do not seem to us to be simply two equally valid choices.

Some differences, however, are matters of personal taste. Preferring one activity to another generally gives us no reason to impose it on our neighbour. But condemning the torture of an innocent person seems to mean something more. We think this action is wrong even if the person doing it enjoys it.

The word objective expresses this difference. Something is objective if it remains true regardless of what people think about it. Saying that torture is objectively wrong therefore means that its injustice does not depend on our approval. An entire society could accept it without making it right.

A moral obligation is a duty that requires us to act or to refrain from acting. It can go against our interests and desires. For example, respecting an innocent person would remain a duty even if harming them brought us great rewards. It is precisely this binding force of duty that the article seeks to understand.

We also distinguish a moral value from a moral obligation. A moral value is something we recognise as good, such as justice. An obligation tells us what this good requires us to do in practice: not to convict an innocent person, for example. Recognising an ideal and being bound to respect it are two related questions.

The moral argument is a line of reasoning that connects these duties to God. It has three simple steps:

1. If God does not exist, no moral duty is truly binding on everyone.
2. But some moral duties are truly binding on everyone.
3. Therefore God exists.

The conclusion does follow from the first two statements. But that is not enough to establish that it is true. We must also show why each of these statements deserves to be accepted. Much of the debate concerns precisely how to defend them.

The foundation of a duty is what makes it truly valid. Knowing a rule and understanding its foundation are not the same thing. We can know that an action is unjust without having thought about what makes that judgement true.

An atheist is a person who does not believe in God. An atheist can defend the weak, act courageously and recognise injustice just as sincerely as a believer. The moral argument does not question this possibility at all. It asks what would provide a foundation for everyone's duties in a world where God did not exist.

The proposed answer is a source of goodness that goes beyond human decisions. This is the meaning of the word transcendent in this debate: something that does not depend on us and goes beyond our authority. According to defenders of the argument, God thus gives duty a binding force that our preferences cannot provide.

The history of the argument brings together thinkers who did not all follow exactly the same path. Some begin with duty, others with our sense of having done wrong or our outrage at injustice.

The philosopher Immanuel Kant develops his thinking in the Critique of Practical Reason, published in 1788. He asks how we can act in accordance with what is good. Virtue here means conduct that genuinely seeks to do good. Yet a virtuous person is not always happy.

Kant reflects on the ultimate harmony between this right conduct and happiness. He believes that this harmony requires God and a life beyond death. Human freedom also matters in his thinking: being responsible requires the ability to choose. This ability to choose is called free will. The question of choice is also explored in the article on free will.

Kant therefore does not present God as the conclusion of a mathematical calculation. His reasoning concerns the conditions for a consistent moral life and its fulfilment. It differs from the three-step argument presented above. Both, however, take our experience of duty seriously.^[1]

The writer Fyodor Dostoevsky explores a similar concern in The Brothers Karamazov, published in 1880. The character Ivan Karamazov links the disappearance of virtue to the absence of immortality. Immortality here means that a person's life does not end with death. His brother Dmitri takes up this concern in turn.

The phrase if God does not exist, everything is permitted is commonly used to sum up this thinking. Jean-Paul Sartre helped to popularise it. But it would be inaccurate to present the whole contemporary argument as a quotation from Dostoevsky. The conclusion therefore God exists belongs to a later reconstruction of the argument.^[2]

C. S. Lewis, the author of Mere Christianity in 1952, starts with a more everyday experience. When we feel we have been wronged, we generally protest against an injustice. We do not simply say that we dislike the action. We expect the other person to recognise a rule that applies equally to them.

Yet someone may claim that everyone chooses their own morality, then condemn an injustice as truly wrong. Lewis asks whether these two attitudes are consistent.

Lewis compares this situation to a mistake in a calculation. Someone can make a mistake without the correct answer ceasing to exist. In the same way, moral errors would not prove that good and evil do not exist. The way we protest would show that we already rely on their reality.^[3]

The philosopher William Lane Craig presents the contemporary formulation in Reasonable Faith, particularly in the 2008 edition. He stresses duties that are truly binding on us. He also points out that an objective truth does not need everyone's approval to remain true.^[4]

Writing in French, Matthieu Lavagna takes up this approach in Soyez rationnel, devenez catholique !, published in 2022. The 2023 edition is the reference used for this article. Lavagna defends the two premises of the argument, then answers the objections. His chapter provides most of the account followed here.^[5]

Cardinal John Henry Newman follows a complementary path, focused on conscience. Conscience is our ability to judge our own actions morally. It can approve of us, but it can also reproach us for an action that no one knows about. We then feel that we must answer for what we have done.

In a sermon from 1830, Newman describes this experience. He uses the word soul to refer to the person in their inner life:

“Conscience implies a relation between the soul and a something exterior, and that, moreover, superior to itself; a relation to an excellence which it does not possess, and to a tribunal over which it has no power.”^[6]

Newman means that we sense an authority greater than ourselves. We cannot decide on our own that a wrong action becomes good. The image of a tribunal expresses this authority that judges our actions.

For Newman, this authority points towards someone, rather than a mere impersonal rule. He returns to this conviction in his Letter to the Duke of Norfolk, in 1875.^[7]

The first statement is the one most directly challenged: without God, no moral duty would be objectively binding. Its defenders ask what could give a rule authority over all human beings. An individual preference is not enough. A society's decision also seems to leave a difficulty.

Suppose a group approves of an injustice. Its decision can explain why this injustice is practised or even imposed. It does not show why it would have become good. Otherwise, condemning an unjust society would mean merely setting another group's preferences against its own.

Lavagna presents a comparison proposed by the philosopher Guillaume Bignon: the rules of volleyball. In this comparison, the rules have authority because they were set by the game's creator. Juggling the ball instead of sending it over the net is then a mistake.^[8]

Without an official creator of the game, the comparison continues, there are still players, a ball and a net. But no aim has any particular authority over the players. If they do not agree on that aim, their preferences alone cannot settle the matter. Bignon compares this situation to moral duty, which is binding regardless of our decisions.

This comparison does, however, have a specific purpose. It helps us understand what a shared authority means; it does not prove on its own that all morality comes from God. Sports rules concern a defined game. The moral argument must still explain why human duties require a source beyond humanity.

According to its defenders, a purely human authority cannot account for a duty that is valid independently of any human decision. God would be this higher source. Duties would therefore not simply be rules adopted so that we can live together. They would express a good that exists before our decisions and that we can recognise.

Michel-Yves Bolloré and Olivier Bonnassies make the difficulty concrete through an imaginary situation. You would be offered an enormous fortune to press a button. Doing so would kill a family you do not know, far away from you. No one would discover your responsibility, and you would face no threat of punishment.^[9]

The question is then simple: why should you refuse? The immediate answer is that these people's lives matter more than making ourselves rich. Their innocence forbids us from sacrificing them. This prohibition seems to remain valid even if our interests, safety and anonymity are fully guaranteed.

The example does not suggest that non-believers would accept the offer. It highlights what our judgement calls on us to explain. The absence of witnesses does not erase the injustice. Nor does the absence of punishment make the act a morally neutral choice.

The same authors question the limits of a majority decision. Could a vote make slavery or the extermination of the Jews right? It could authorise these acts under a country's laws. But this authorisation would not be enough to make them good.^[10]

We thus distinguish between what an authority allows and what is morally permissible. This difference makes it possible to criticise an unjust law. If voting alone created what is good, no majority could be morally condemned. It would always be right simply because it was in charge.

The argument's first statement seeks to explain why duty holds firm in this way. Our interests do not remove it; our collective decisions do not seem to create it. Its defenders see this as a sign of an authority beyond us. The debate then turns to examining the other explanations proposed.

One common response appeals to our biological history. Helping one another is thought to have favoured the survival of human groups. Education would then have passed on habits useful for living together. This proposal seeks to explain why we feel sympathy or disgust in response to certain actions.

Empathy is the ability to imagine what another person is feeling. It helps explain our desire to help someone who is suffering. But recognising this tendency does not settle the whole question. Why should I follow it when it conflicts with my interests?

The objection also appeals to biological evolution. Here, this means the explanation proposed through changes in living things over generations. Even if we grant this explanation for the sake of discussion, a gap remains. The supposed origin of an inclination does not yet show why it deserves to be followed.

Explaining how we acquired a habit answers a question about how it arose. Justifying that habit answers another question: is it good? Education can pass on an unjust rule. Knowing whom we received it from does not yet tell us whether we should keep it.

The difficulty also appears with our other tendencies. The biological history used to explain mutual help is also used to explain aggression and domination. If their origin were enough to justify them, how could we choose between them? Moral judgement seems to be precisely what allows us to resist some of our tendencies.

Materialism is the view that all reality amounts to matter and its transformations. Lavagna asks how this view can provide a foundation for specifically human duties. The philosopher Richard Taylor illustrates this difficulty through animal behaviour. A bird that catches a fish does not commit murder.^[11]

We do not apply to this bird the standards we apply to a person. We therefore need to explain what makes a human being morally responsible. Simply observing this is not yet enough to provide its foundation. According to the argument, a purely material description of humanity leaves this question open.

This does not allow us to conclude that all atheists think alike. Some defend moral truths independent of God, as we will see later. Others describe a difficulty similar to the one Lavagna highlights. Their reflections show that the question goes beyond the debate between believers and non-believers alone.

According to the passages reported by Lavagna, Jean-Paul Sartre stresses the absence of values given in advance if God does not exist. Human beings must then choose without being able to rely on an already established moral order. This freedom comes with a deep sense of abandonment.^[12]

Albert Camus examines the danger of a world in which no values were upheld. Force and effectiveness could then replace the distinction between just and unjust. Richard Dawkins, a biologist, describes a universe that is fundamentally indifferent to good and evil.^[13][14]

The philosopher Michael Ruse presents morality as a biological aid to survival and reproduction. But, according to Lavagna, he goes further. He considers its claim to describe an objective good to be an illusion. According to this passage, morality helps us survive without expressing a truth independent of us.^[15]

Richard Taylor, for his part, argues that a moral obligation becomes impossible to understand without God to give it authority. These positions are summarised here from Lavagna's account. They are not word-for-word quotations checked against the original works.^[16]

These authors do not develop a shared doctrine. Lavagna nevertheless sees these passages as support for his first premise. He reads them as acknowledging that, without God, duties lose their objective foundation. This reading by Lavagna does not allow us to attribute it to all atheists.^[17]

The argument must also defend its second premise: some actions are truly unjust. It does not require every moral question to be easy to resolve. Nor does it require all our first reactions to be right. It is enough for some duties to be true regardless of opinions.

Torturing an innocent person for pleasure is one of the central examples. We generally do not think it becomes acceptable if the torturer approves of it. We do not condemn it merely because we dislike it. We believe there is a real reason not to do it.

Lavagna compares this certainty to our condemnation of slavery and sexual violence against children. These examples are serious because the question is serious too. It concerns whether the victims have truly suffered an injustice. Or whether we are merely expressing our disagreement with their attackers.^[18]

A strong feeling is not automatically proof. We can be mistaken in our judgements, and conscience needs to be enlightened. But the possibility of error does not justify rejecting all our judgements. As Lewis pointed out, a wrong calculation does not eliminate correct answers.

According to the passage reported by Lavagna, the atheist philosopher David Brink believes that we would need strong reasons to abandon moral objectivity. It is therefore a defensible starting point. Anyone who rejects it must explain why our firmest convictions would be misleading.^[19]

Lavagna also reports that Michael Ruse compares accepting sexual violence against young children to an obvious error in calculation. This remark illustrates the strength of certain moral judgements. Even for an author who questions their foundation, rejecting them remains deeply difficult.^[20]

Human rights raise the same question in a positive form. Affirming these rights means holding that certain protections are owed to every person. They should not depend on how popular or useful that person is. Someone rejected by everyone would still retain their dignity.

Human dignity here means the worth of a person who deserves respect simply because they are human. Lavagna reports a stronger idea from the atheist philosopher Raimond Gaita. Only a believer could speak seriously of the sacredness of the person and of unconditional respect. A believer could also speak of rights that cannot be taken away from that person.^[21]

This means that a person has value in their own right and does not merely serve others. The reported remark concerns how to provide a foundation for this dignity and express it. It does not mean that a non-believer would be unable to respect others. The argument asks what makes this dignity real and lasting.

It is therefore not enough to observe that our societies speak of rights. We need to understand why these rights would remain valid when a society denies them. According to defenders of the moral argument, God provides this foundation. A person's worth would then depend on no vote or collective advantage.

A first objection highlights the diversity of cultures. Some societies approve of practices that others condemn. How can we speak of objective morality in the face of such disagreements? The objection deserves an answer, since we certainly do not find the same judgements everywhere.

The response distinguishes what is true from what is recognised. A universally recognised rule would be accepted by everyone. An objective rule would be true regardless of this acceptance. These two ideas are distinct: a truth can go unrecognised or be rejected.

Disagreement therefore does not, on its own, prove that truth does not exist. When two answers to the same calculation contradict each other, we do not conclude that all answers are equally valid. In the moral debate, we still need to look for reasons that allow us to judge practices.^[22]

This response does not make every case simple. It establishes only that a whole society can be mistaken. A civilisation could accept an injustice without turning it into something good. This is what allows us to condemn slavery even where it was approved.

Lavagna adds a Christian explanation for this difficulty in recognising what is good: original sin. This means the wound left in humanity by the sin of our first parents. This wound also affects our judgement. The existence of a moral law therefore does not imply that everyone understands it perfectly.^[23]

Another objection concerns a believer's reasons for acting. If a believer acts only to receive a reward or avoid punishment, their behaviour seems self-interested. Respecting someone to gain an advantage seems different from respecting them for their own sake. This criticism raises a real difficulty.

But the moral argument does not base goodness on the fear of punishment. It bases it on God as the source of goodness. The question of duty's foundation remains distinct from our personal motives. A duty can be real even when someone fulfils it for the wrong reasons.

Lavagna therefore responds that a believer can seek what is good for its own sake. Respecting a person does not necessarily mean calculating what God will give in return. Love of God and neighbour can inspire a selfless action. The reasoning in no way requires us to reduce morality to a search for rewards.^[24]

An ancient objection asks a crucial question: what is the relationship between God and goodness? It comes from the dialogue Euthyphro, by the philosopher Plato. A dilemma presents two possibilities that both seem to leave a difficulty. This one is called the Euthyphro dilemma.

The first possibility would be that an action becomes good solely because God commands it. Goodness would then depend on a decision that need not have a reason. God could have commanded hatred, and it would have become good. This seems to strip the word good of its usual meaning.

The second possibility would be that God commands an action because it is already good independently of him. God would then recognise a good outside himself. But he would no longer be its foundation. The moral argument would seem to lose what it sought to establish.

The objection asks why his commandments are good. Simply saying that God has greater power does not resolve the difficulty. The most powerful is not right merely because he can impose his will.

The classic response, associated with Saint Thomas Aquinas and taken up by Craig and Lavagna, proposes a third possibility. God does not create goodness through a changing decision. Nor does he receive a rule higher than himself. God himself is goodness.

Speaking of God's nature here means speaking of what he is. In this Christian response, justice and love belong to what God is. His commandments express this goodness. He therefore cannot make cruelty good through a mere decision.^[25]

This response holds two statements together. Goodness depends on God, but it does not depend on a whim. God is not presented as a leader who can change the rules according to his mood. He is the unchanging source of the goodness that his commandments express.

The debate then concerns how sound this third possibility is. For defenders of the argument, it shows that the two answers initially proposed do not cover every possibility. Divine goodness provides a foundation for duty without making goodness changeable or placing God under an external law.

A more direct objection proposes objective morality without God. The philosopher John Stuart Mill defends utilitarianism, particularly in his work of 1863. This doctrine judges actions by their consequences for happiness and suffering. It seeks to promote collective happiness and reduce suffering.^[26]

This proposal does not amount to saying that everyone chooses their own preferences. It provides a shared standard for comparing actions. A decision would be better if it improved the lives of those concerned to a greater degree. It therefore directly challenges the idea that God is essential to any objective morality.

The article's first response concerns the foundation of this standard. Why should we seek everyone's happiness rather than our own advantage alone? Saying that this increases happiness describes the desired result. It does not yet show why seeking it is a duty for everyone.

A defender of utilitarianism may regard happiness as a fundamental good. Why would it be objectively good to seek to make it as great as possible? But why would everyone have a duty to seek everyone's happiness? The moral argument does not deny the importance of happiness. It asks why this importance would be binding on someone who refuses to recognise it.

A second response concerns respect for persons. Suppose that making an innocent person suffer increases the happiness of a majority. If only the collective result decides, what principle protects this innocent person? The risk is treating that person as a means of serving others.

The criticism targets this calculation when it becomes the sole standard of goodness. It does not mean that every defender of utilitarianism wants to sacrifice innocent people. It asks how their protection can remain firm if it depends solely on expected consequences. Must a person be respected even when this comes at a cost to the group?

Another response is to reject the very existence of objective moral truths. The philosopher John Leslie Mackie develops this position in Ethics: Inventing Right and Wrong, in 1977. It is called error theory. According to this theory, our judgements that actions are objectively right or wrong assume something that does not exist. This claim is where the error lies.^[27]

For Mackie, such moral properties would be very unlike everything else in a purely material world. He therefore prefers to give up belief in their existence. This does not necessarily mean that he approves of violence or abandons all rules. His claim concerns what our condemnations can assert as a truth independent of us.

This objection mainly challenges the argument's second premise. The believer affirms that some actions are truly wrong and seeks their foundation in God. Mackie questions this moral reality itself. The disagreement therefore concerns how much trust we should place in our most fundamental judgements.

The response defended in the article returns to the torture of innocent people. Should we abandon the conviction that it is truly unjust in order to retain a certain description of the world? According to Lavagna, the cost of giving up this conviction is too high. Our strongest moral certainties instead give us a reason to re-examine that description.

The atheist philosopher Derek Parfit proposes another path in On What Matters, in 2011. He defends objective moral truths without making them depend on God or matter. The comparison is with mathematical truths. A truth could be real without being a material object or someone's command.^[28]

This proposal deserves to be distinguished from calculating collective happiness. Parfit seeks to bring together several ways of understanding duty. He therefore does not reduce his whole moral philosophy to Mill's. His work shows that an atheist can seriously defend the existence of moral truths.

The article's response concerns what these truths would still struggle to explain. Why would they have authority over us? How could our reason know them? Even if a moral truth exists, why does it oblige me to refuse the fortune offered in the button example? According to defenders of the moral argument, affirming their existence does not yet fully answer these two questions.

The first statement of the argument therefore remains a real point of debate. We cannot assume that all non-believers accept it. The argument defends it by asking for a complete explanation of duty. It proposes God as the source of goodness, of its authority and of our ability to recognise it.

The Christian response connects with the doctrine of natural moral law. This expression means the demands of goodness that human reason can recognise. Recognising them does not first require religious instruction. The word natural therefore does not mean here that all our instincts are good.

This doctrine explains why a person without faith can know real duties. The ability to recognise what is good belongs to human beings. Faith does not make the non-believer a person without a conscience. It offers an explanation of this ability and of its origin in God.

The Catechism of the Catholic Church, which presents the Church's teaching, speaks of the precepts of natural law. Precepts are rules that tell us what we must do.

“The natural law, present in the heart of each man and established by reason, is universal in its precepts and its authority extends to all men. It expresses the dignity of the person and determines the basis for his fundamental rights and duties.”^[29]

Their universal scope here means that they concern all human beings. This does not mean that everyone recognises them without difficulty. The scope of a duty and our knowledge of it remain distinct.

Natural law does not change with opinions or historical periods. Our understanding of it, however, can be imperfect.^[30]

Saint Thomas Aquinas expresses the first principle of this law in a few words:

“good is to be done and pursued, and evil is to be avoided”^[31]

This formula gives our choices their basic direction. Other moral rules are connected to this first principle. It does not automatically provide the answer to every difficult situation. Our judgement needs to learn and reflect. This is why the Church also asks that conscience be formed and enlightened.^[32]

A council brings together the leaders of the Church with the pope. The Second Vatican Council describes conscience as the inner place where we encounter God. This conscience calls each of us personally to do good. It is therefore distinct from the simple desire to do what we please.^[33]

Saint Paul already spoke of this ability to recognise what is good. He speaks of people who have not received the religious law mentioned in his letter. The word Gentiles refers to these people in this passage. Yet they can recognise what is good.

“When Gentiles who have not the law do by nature what the law requires, they are a law to themselves, even though they do not have the law. They show that what the law requires is written on their hearts, while their conscience also bears witness [...]”^[34]

The moral argument connects with this conviction: knowing what is good does not depend on religious membership. Its foundation may go beyond what any individual knows about it.

However, the argument does not prove the whole Christian faith on its own. According to its defenders, it points towards God as the source of goodness. The cosmological argument examines the question of the universe's origin. The article on the fine-tuning of the universe looks at the physical conditions favourable to life.

Identifying this source with the God revealed in Jesus Christ also requires us to examine history. The articles on the historical existence of Jesus and the resurrection of Jesus continue this investigation. The different arguments can converge. None needs to claim to answer every question on its own.

• Some actions seem unjust regardless of opinions, laws and interests.
• A non-believer can recognise what is good and act with courage and generosity.
• The argument asks what makes our duties truly valid for everyone.
• Explaining the origin of a feeling is not enough to justify what it asks of us.
• Moral disagreements do not, on their own, prove that all answers are equally valid.
• The objections concern the foundation of duties or their very reality.
• The Christian response grounds goodness in what God is: justice and love.

The moral argument thus starts from a conviction that concerns our life together. A victim retains their worth even when no one defends them. Their attacker cannot erase the injustice by declaring that they think differently. And a society does not make everything right through a majority decision.

If the two premises are true, the conclusion follows: God exists. Lavagna considers them sound and sees God as the source of the goodness that is binding on us.^[35] Goodness thus has its source beyond our interests and power struggles. Conscience opens us to this real good, which calls everyone and excludes no one.