On Laws

Quick Facts

• Full title: Tractatus de legibus ac Deo legislatore, usually shortened to On Laws or De Legibus
• Author: Francisco Suarez
• Published: 1612, while Suarez was teaching in Coimbra
• Genre: scholastic treatise on law, moral obligation, political authority, and God as lawgiver
• Main fields: Natural Law Theory, political theology, legal philosophy, moral theology
• Main inheritance: Thomas Aquinas, especially the Treatise on Law in the Summa Theologiae
• Main claim: law is not just advice, force, or private preference. Real law comes from legitimate authority, aims at the common good, and binds people morally.

The Problem

On Laws asks a basic but huge question: what makes a law actually binding?

A ruler can threaten punishment. A parent can give advice. A custom can be old. A theologian can point to God. But none of that by itself explains what law is. Suarez wants to know when a command becomes a true law, why conscience should care about it, and what limits human rulers have.

The problem matters because Suarez is writing in a world where church, empire, monarchy, colonial power, universities, and canon law all overlap. If every king rules directly by divine right, ordinary people have almost no political standing. If law is only human command, then unjust commands look like law just because officials said so. Suarez tries to give a middle answer: political authority is real, but it is not magic. It has a moral structure.

In One Minute

On Laws is Suarez's big account of eternal law, natural law, human law, divine law, obligation, and political authority. It is late scholastic philosophy doing legal theory: slow, careful, full of distinctions, but aimed at a practical issue. Why should anyone obey law, and when does law stop being legitimate?

Suarez agrees with Aquinas that law must be ordered to the common good. Law is not supposed to be one person's private will dressed up in official clothing. But Suarez pushes harder on obligation. A true law does not merely describe what is reasonable. It obliges. It comes from a legitimate lawgiver and places people under a real duty.

That is why the book matters for politics. Suarez says human beings are naturally social, so they need political community. But no particular person is born with natural political power over everyone else. Political power starts in the community and can be given to rulers. A king may rule, but he does not own the people.

The Main Argument

Suarez's first move is to define law carefully. A law is not just a smart suggestion. It is not just a threat. It is not just a moral truth floating in the air. A law is a command from someone with proper authority, directed toward the common good, made known to the people who are bound by it.

This is close to Aquinas, but Suarez puts more weight on the will of the lawgiver. For Aquinas, law is famously an ordinance of reason for the common good, made by one who has care of the community, and promulgated. Suarez accepts much of that, but he thinks law also requires command. Reason can show what is good. But law, strictly speaking, happens when legitimate authority says, "This is to be done," or "This is forbidden."

A simple example: reason can tell you that safe roads matter. But a speed limit becomes law only when a public authority with care for the community sets the rule and makes it known. The rule is not valid just because the number is clever. It is law because a legitimate authority uses public command for a common good.

Suarez then places human law inside a larger order. Eternal law is God's wise ordering of all things. Natural law is the part of that order that rational creatures can know by reason. Human law is the set of concrete rules made by political authorities. Divine positive law is law known through revelation, such as commands given in scripture. The point is not to make four random boxes. The point is to show how different kinds of law can bind in different ways.

Natural law is central. For Suarez, some actions are wrong because of what they are. Murder, perjury, and betrayal are not wrong only because God happens to dislike them. They damage goods that reason can recognize: life, truth, trust, justice, and social peace. But Suarez also wants natural law to be real law, not merely moral insight. So he says natural law has force as law because God, as creator and governor of rational nature, commands creatures to follow the good reason can recognize.

That gives Suarez a "both sides" answer. Against pure divine command theory, he says morality is not arbitrary. God does not make cruelty good by liking it. Against a purely rational morality with no lawgiver, he says obligation has the shape of command. If a thing is naturally wrong, it is also forbidden by God as lawgiver.

The political argument follows from the same pattern. Human beings are social. Families alone cannot provide courts, defense, public peace, trade rules, punishment, education, and the stable conditions of common life. So political community is natural. But Suarez denies that nature names one person as king over everyone else. No one is born with political jurisdiction over another human being simply by being older, stronger, richer, or descended from a famous ancestor.

Political authority therefore belongs first to the community. The community can organize that authority in different ways: monarchy, aristocracy, democracy, or mixed government. Suarez personally thinks monarchy can be very useful, but he does not think natural law requires monarchy. The form of government is partly a matter of human choice.

Once authority is transferred to rulers, the transfer is serious. Suarez is not saying every citizen can cancel the government whenever annoyed. Political order needs stability. But the ruler's authority remains for the common good. If rule becomes tyranny, usurpation, or destruction of the community, the ruler loses the moral shape that made authority legitimate in the first place.

Key Ideas With Examples

• Law: a public command from legitimate authority for the common good. If a city sets fire codes to prevent buildings from killing people, that is law in the proper sense. If a ruler orders a personal enemy punished for no public reason, that is closer to abuse than law.

• Obligation: being morally bound to do or avoid something. If a law is legitimate, you do not obey it only because you fear punishment. You have a duty to obey it. For Suarez, obligation is why law is stronger than advice.

• Common good: the shared conditions that let a community live well. Courts, peace, honest weights, safe roads, public order, and protection from violence are common goods. A law about taxes can be legitimate if it funds those goods. It becomes corrupt if it only feeds a ruler's luxury.

• Eternal law: God's ordering wisdom over creation. Think of it as the deepest order of reality: not a written code on paper, but God's rational governance of everything toward its proper good.

• Natural law: the moral law rational creatures can know from human nature and practical reason. Do not murder, do not lie under oath, keep basic promises, care for children, and seek justice are examples because they protect goods human life needs.

• Human law: concrete rules made by political communities. Natural law says public safety matters. Human law decides the local details: speed limits, court procedures, tax rates, property records, military rules, and penalties.

• Divine positive law: law revealed by God rather than discovered by ordinary reason alone. In Christian terms, some biblical commands guide people toward salvation, worship, grace, or religious life in ways natural reason would not fully supply by itself.

• Promulgation: law must be made known. A secret rule that no one can find is not a fair basis for blame. If a city creates a new rule, people need some public way to know what the rule is.

• Consent and community: political authority starts in the community and is organized by explicit or tacit agreement. "Tacit" means not always a signed contract. People may participate in a political order through inherited institutions, public recognition, and shared life.

• Tyranny: rule against the common good. A bad ruler is not automatically a tyrant in the strongest sense. But a ruler who treats public power as private property, destroys law, or attacks the community's basic goods has broken the point of authority.

Why It Matters

On Laws matters because it gives one of the most systematic late scholastic accounts of law. It explains law from the top down and the bottom up: from God's eternal order, and from human communities that need concrete rules.

It also matters because it helps bridge medieval scholasticism and early modern political thought. Suarez still writes as a Catholic theologian, but he is dealing with problems that become central to modern politics: sovereignty, consent, public authority, resistance, natural rights, international law, and the limits of rulers.

The book is especially important for Natural Law Theory. It says human law is not valid in the deepest sense just because power enforces it. Law has to answer to reason, moral order, and the common good. That idea becomes a major reference point for later debates about unjust laws, rights, political obligation, and state authority.

Suarez is also useful because he is not easy to flatten. He is not a modern liberal democrat. He is not a simple divine-right monarchist. He is not a secular legal positivist. He gives a layered theory: God is the ultimate source of order, reason can know real moral goods, communities hold political power naturally, and rulers govern legitimately only for the common good.

Proponents, Critics, and Opponents

Suarez's supporters and heirs are mainly late scholastic, Jesuit, Catholic, and natural law thinkers. He belongs with the School of Salamanca and the wider revival of scholastic philosophy after the Middle Ages. Later natural law writers such as Hugo Grotius and Samuel Pufendorf did not simply copy him, but Suarez helped shape the legal and moral vocabulary they inherited.

Thomas Aquinas is the key predecessor. Suarez develops Aquinas's law theory, especially the ideas of eternal law, natural law, human law, common good, and practical reason. The difference is emphasis. Aquinas sounds more like "law is reason for the common good." Suarez sounds more like "law is reasoned command from legitimate authority for the common good."

William of Ockham is a useful contrast. Ockham tends to put more stress on divine will and the limits of church power. Suarez gives a more systematic account of law and obligation, while still insisting that political power has limits.

Royal divine-right theorists opposed the Suarezan line because it makes kings answerable to the community and natural law. Robert Filmer later attacked theories that put political power originally in the people. Thomas Hobbes moves in another direction: he makes civil authority much more absolute because he fears conflict, civil war, and divided sovereignty.

Modern legal positivists also push against Suarez, though usually from a different angle. They argue that law can be identified by social facts: who enacted it, what courts recognize, what procedures were followed. Suarez would answer that this may identify a rule as an official rule, but it does not yet explain whether it binds conscience as just law.

Related Pages

• Francisco Suarez
• Thomas Aquinas
• Summa Theologiae
• Natural Law Theory
• Late Scholasticism
• Catholic Scholasticism
• Metaphysical Disputations
• Defense of the Catholic and Apostolic Faith
• Dialogue