Natural Law School of Jurisprudence

The Natural School says that some laws are eternal. They do not change, and nothing that people believe or feel can touch them. No State has to write them down for them to exist. You will see them called natural law, moral law, divine law, the law of reason and the law of God.

Natural law rests on an a priori idea.

The school says we know the basic rules of right and wrong in the first way. You do not have to see a murder to know that murder is wrong. The details that change from country to country, such as how a contract must be made, we learn the second way.

It helps to compare natural law with positive law, which is law made by a State and applied by its courts. You can find positive law in a statute or a judgment. You will not find natural law there, because no legislature passed it. The theory says we find it by using reason on human nature and on what social life needs.

There is no single accepted definition. Each jurist and philosopher defined natural law in terms of his own thinking.

• Cicero (106 to 43 BC): Law is the highest reason, found in nature. He said that law tells us what to do and what not to do. For him, true law is the same everywhere and in every age.
• Thomas Aquinas (1225 to 1274): Natural law is the part of God's plan that people can understand through reason. He saw it as the way human beings share in God's plan for the world.
• Hugo Grotius (1583 to 1645): Natural law is a dictate of right reason. It marks an act as morally wrong or morally necessary, depending on whether it fits man's rational and social nature.
• William Blackstone: The law of nature binds everywhere, and no human law can go against it. In his Commentaries on the Laws of England (1765 to 1769), he wrote that the law of nature binds in every country and at all times. He added that no human law is valid if it is contrary to it.

The words differ, but the point is the same in all four. The law comes from reason or nature, it applies to everyone, and it stands above the law of any State.

1. A command does not become law just because a ruler gave it. It must also fit with justice and reason.
2. State law is measured against a higher standard. Aquinas said that human law is valid only when it agrees with natural law. A rule that contradicts natural law is not really law. It is only a corruption of law. The Latin phrase lex iniusta non est lex, which means "an unjust law is not law", sums this up.
3. Natural law explains why law binds. We should obey a rule because it is just and serves the common good, and not only because we fear the punishment. This is the sharpest difference from the analytical school. That school says that law is the command of a sovereign and is valid whatever its moral quality.
4. Natural law gives a way to criticise law and ask for change. Ideas such as justice, equality and human rights all rest on it.
5. The Nuremberg trials show the idea in use. After the Second World War, many Nazi leaders said that they had only followed the law of their own country. However, the tribunal did not accept this as a full defence. It treated some acts as crimes, whatever the German law of the time said.

1. Eternal and unchangeable. Natural law does not change with time or place. This is why Plato thought of goodness, virtue and honesty as eternal forms.
2. Universal. It applies to every human being, because it comes from reason and human nature, and everyone shares those.
3. Based on reason. People find it by thinking, and not by reading statutes. That is why it is also called the law of reason.
4. A priori. Its basic principles can be known without experience.
5. Higher than positive law. A State law is valid only if it agrees with natural law.
6. Links law and morality. For this school, law is a moral order, and its purpose is justice.
7. Source of rights. The social contract philosophers said that people have rights to life, liberty and property before any State exists. Modern human rights grew out of this idea.
8. Changing sources. Early jurists and philosophers found natural law in the order of nature, medieval writers in the will of God, and later writers in human reason and an agreement between free people. All of them put the source outside the ruler's will.

The theory developed over about twenty-five centuries. It is usually divided into four periods -

1. Ancient (Heraclitus, Socrates, Plato, Aristotle, Zeno and Cicero)
2. Medieval (Aquinas)
3. Renaissance (Hobbes, Locke and Rousseau)
4. Modern (Stammler, Rawls and Hall)

Ancient period

The philosophers of Greece and Rome were searching for a universal order in nature and in human life. They believed that law cannot be separated from nature itself, and that nature is governed by reason, order and morality. They noticed that, despite the apparent chaos of the world, the universe runs by laws. The sun rises, the seasons change, and humans are born and die. Therefore, they concluded that law is a rational principle that guides people toward their ultimate purpose, which is their good.

Greek philosophers

1. Heraclitus (about 530 to 470 BC): The universe follows a rational order. He called this order the Logos. The Logos is the reason or law that unites opposites and brings harmony out of conflict. According to him, the universe is not chaotic. It has a definite order, a rhythm and connections between all things. Natural law is expressed through destiny, order and reason, and it governs everything from the smallest motion to the whole of existence. He stressed that this law is constant and that people can discover it through reason. A law controls the movement of the planets, and in the same way a moral law controls human behaviour. When people act against reason, they go against nature itself.
2. Socrates (470 to 399 BC): Law must rest on human virtue. Socrates moved the focus from nature to human ethics. He stressed virtue, which means behaviour that shows high moral standards, and he identified it with knowing what is good. He taught by asking questions, in what is called the Socratic Method. This method encourages reasoned inquiry and not blind obedience. So he saw natural law as something that people can reach by thinking, and its aim is to guide them toward virtue. For example, if a law orders you to do something plainly unjust, such as killing an innocent person, reason tells you that it is wrong.
3. Plato (427 to 347 BC): Law is a reflection of perfect and eternal forms. Plato, the student of Socrates, developed these ideas into his Doctrine of Forms. He believed that there is a perfect and eternal world of ideas, such as justice, goodness and truth, in a higher realm. The laws of the physical world are only imperfect reflections of these ideal forms. According to Plato, true law conforms to these unchanging ideals, so law is a pursuit of perfect justice and not a matter of social agreement. For example, different societies may define justice differently, but the idea of justice, which means fairness and equality, stays the same. This is why Plato is called the idealist.
4. Aristotle (384 to 322 BC): Law is linked to the purpose of human life. Aristotle, the student of Plato, rejected the existence of separate ideal forms. He explained that forms exist in things themselves and define their nature and purpose. He saw natural law as matching the telos, which means the purpose, of human beings. That purpose is to reach happiness or flourishing through reason and virtue. In this way, his view moves law away from abstract ideals and toward practical human purposes.

Rome

1. Zeno of Citium (334 to 262 BC): Living in harmony with reason is the key to virtue. Zeno founded Stoicism. He taught that living in harmony with universal reason, which is natural law, is the key to virtue. The Romans took in this idea, and it led to their well-known three divisions of law:
   • Jus civile: the civil law, which applied to Roman citizens.
   • Jus gentium: the law of nations, which applied to foreigners.
   • Jus naturale: the law of nature, which is common to all mankind.
2. Cicero: An unjust law is not true law. Cicero combined Greek philosophy with Roman practical sense. He said that law is the highest reason, found in nature. Any law that contradicts natural law is unjust and is not true law.

The ancient thinkers all linked law to reason, moral virtue and the order of the universe. However, they differed on how abstract or how practical that link was, from Plato's idealism to Aristotle's practical purpose. In each case, law was a guide to justice that is rooted in nature.

Medieval period: Divine Law and Reason

With the rise of Christianity, natural law was read through a religious lens, and law came to be seen as God's command. The thinkers of this period tried to bring reason and faith together, in what is called the Christian synthesis. They grounded law in God's eternal plan, and they said that people can understand a part of that plan through natural reason.

1. Thomas Aquinas (1225 to 1274): Law has four levels, and human law must follow the higher ones. Aquinas was the most prominent natural law philosopher of this period. He wrote in the thirteenth century and built a systematic order of laws:
   • Eternal law: God's overall plan and reason, which govern everything.
   • Natural law: the human share in eternal law, which people reach through reason.
   • Divine law: the law that God revealed through the Scriptures.
   • Human law: the positive law that people make, which must follow natural and divine law.
2. Natural law is moral and rational: It tells people to do good and avoid evil. According to Aquinas, positive laws are valid only if they agree with natural law. His work made religious morality rational, and it strengthened the moral authority of the Church by supporting it with reason.
3. Aquinas made three main points.
   • Natural law rests on both reason and faith.
   • The legitimacy of law depends on its agreement with divine justice.
   • Human reason is capable but limited, and divine law completes what reason cannot know.
4. The purpose of law: Human good and eternal salvation. Aquinas joined classical natural law to Christian doctrine. His work served as a bridge between philosophy and theology, and it shaped political thought in Europe for centuries.

Renaissance period

From about the fourteenth to the 17th century, natural law moved away from religion. Grotius argued that its basic rules would hold even without God, because they come from human reason and from man's social nature. The main contribution of this period was the Social Contract Theory. In the beginning, people lived in a "state of nature" with no rights and no duties. Then they made a contract. Everyone got certain rights, and those rights were protected by putting duties on everyone. Each person has a right to life, for example, so each person has a duty not to kill.

1. Thomas Hobbes (1588–1679): Government must have absolute power to maintain peace. Hobbes believed that without government, people would live in a state of fear and violence, which he called the war of all against all. To escape this situation, people made a social contract and gave their powers to an absolute ruler. The ruler's main duty is to maintain peace and security. For Hobbes, the authority of the ruler cannot be challenged.
2. John Locke (1632–1704): Government must protect people's natural rights. Locke believed that every person naturally has three basic rights: life, liberty and property. People form a government to protect these rights. Unlike Hobbes, Locke supported limited government. If a ruler fails to protect people's rights or misuses power, people have the right to remove that ruler.
3. Jean-Jacques Rousseau (1712–1778): Laws must reflect the general will of the people. Rousseau believed that people should make laws together for the common good. He called this idea the general will. People do not surrender their rights to one ruler; instead, they become part of a political community. A law is legitimate when it reflects the collective will and promotes equality and freedom.

Modern period

The critics. In the nineteenth century, natural law was attacked from several sides.

1. David Hume: Values are subjective, so natural law cannot be proved by reason. By subjective, we mean based on personal feeling and not on facts. Hume argued that values grow out of human feeling and are not discovered through reason. In addition, ideas of justice differ widely from place to place. He also pointed out that you cannot move logically from what is to what ought to be.
2. Jeremy Bentham: Natural rights are only rhetoric. Bentham called natural rights "nonsense upon stilts". Instead, he put social happiness first.
3. John Austin: Law is only the command of a sovereign. Austin rejected natural law altogether. He saw law strictly as the command of a sovereign, enforced by power.

The revival. In the twentieth century, natural law came back, because society still needs some basic values and an ideal of justice. The Nazi legal system showed what can happen when law has no such standard. However, the revival did not bring back the old fixed code. Instead, it tried to join moral ideas to social facts.

1. Rudolf Stammler (1856 to 1938): Natural law with a variable content. Laws differ between customs and societies, so their content is learned from experience. In other words, it is a posteriori. However, all laws aim toward universal ends, which are justice and fairness. So there is no fixed code for all times, but there is a fixed ideal of justice.
2. John Rawls (1921 to 2002): Justice as fairness. In A Theory of Justice (1971), Rawls built a modern social contract theory. He imagined a hypothetical original position, where people decide the principles of a just society behind a veil of ignorance. In other words, they decide without knowing their own social status. His approach joins the study of law with moral philosophy. It bases modern natural law on justice as fairness, and not on divine commands or fixed ideals.
3. Jerome Hall (1901 to 1992): Integrative jurisprudence. Hall suggested bringing together three views of law: natural law, which stands for morality, positive law, which stands for the State, and the sociological view, which stands for the structure of society.

The Renaissance and modern social contract thinkers shifted the basis of law towards human reason and people's consent. They focused on how to balance individual freedom with the authority of the government. Later thinkers either criticised these ideas or tried to develop them further. They focused on fairness, the role of society and the relationship between moral values and practical realities.

The theory has three main weaknesses.

It is uncertain.

People who agree that natural law exists often disagree on what it says. Hume's point about different ideas of justice in different places is hard to answer, and jurists and philosophers have found very different rules in "nature" and "reason".

Who decides?

If a judge can set aside a statute because he thinks it clashes with natural law, he is putting his own view in place of the legislature's. The analytical school says this makes the law uncertain and gives judges too much power.

It can be misused.

Jurists have used natural law for opposite purposes. Hobbes used it to support an absolute ruler. Locke used it to justify revolution.

Defenders answer that the theory gives law a moral limit that a purely positivist approach lacks, and that it has been used, as at Nuremberg, to condemn serious injustice carried out under the cover of law.

Natural law theory says that law must meet a standard of justice that does not depend on any ruler's will. Over twenty-five centuries, its supporters have found that standard in the order of nature, the will of God, human reason and the agreement of free people. Its critics ask who gets to say what the standard requires.

Today the theory is not taught as a fixed code of eternal rules. People use it mainly as a test of the moral quality of law and as the source of the idea of human rights. Later jurists, from Stammler to Rawls, have tried to keep that moral test while answering the objections of Hume and Bentham.