# Explain the main features of the classical and medieval conception of natural justice.
## Introduction
The concept of natural justice, or natural law, represents one of the oldest and most enduring traditions in political and legal thought. It posits that there are objective, universal principles of justice and morality that are inherent in human nature or the fabric of the universe itself, and that these principles provide a standard against which the laws made by human societies can be judged. This tradition has evolved significantly over time, and its foundations were laid in the classical and medieval periods. This essay will explain the main features of the classical conception of natural justice, with a focus on the key ideas of Plato and Aristotle, before examining how this tradition was adapted and developed in the medieval period, primarily through the work of Thomas Aquinas. It will demonstrate that while medieval thinkers were heavily indebted to classical philosophy, their integration of Christian theology fundamentally reoriented the ultimate source and justification for natural justice.
## The Classical Conception of Natural Justice
The origins of natural justice in Western thought can be traced to ancient Greece, where philosophers began to distinguish between the particular, changing laws of a city-state (*nomos*) and the universal, unchanging principles of nature (*physis*). The Sophists, for example, often argued that justice was merely a matter of convention or the interest of the stronger party, a view that Plato and Aristotle strongly opposed (Sabine and Thorson, 1973). For them, true justice was not arbitrary but was grounded in a rational and ordered reality.
Plato’s conception of justice is presented most famously in his work, *The Republic*. For Plato, justice is not primarily a set of legal rules but a state of inner harmony and a principle of social order. He argued that the human soul consists of three parts: reason, spirit, and appetite. A just individual is one in whom reason governs the other two parts, creating a state of internal balance. Similarly, a just society is one where each social class—the rulers (philosopher-kings), the auxiliaries (soldiers), and the producers (workers)—performs its proper function in harmony with the others. Justice, therefore, is about maintaining the natural and correct order. The ultimate source of this justice is the transcendent ‘Form of the Good’, an eternal and unchanging ideal that can only be fully comprehended by philosophers through reason. For Plato, then, natural justice is a metaphysical reality, an objective standard that human laws and political structures should seek to emulate (Plato, 2007).
Aristotle, a student of Plato, offered a more worldly and practical account of natural justice. In his *Nicomachean Ethics*, he makes a clear distinction between ‘natural’ justice and ‘legal’ or ‘conventional’ justice. He states that a rule of natural justice is one that “has the same validity everywhere and does not depend on our accepting it or not” (Aristotle, 2004, Book V). In contrast, legal justice refers to matters that are initially indifferent but become binding once a law is established. While Aristotle believed in universal principles, his approach was less abstract than Plato’s. He sought to discover these principles by observing human nature and the purpose (*telos*) of the political community. For Aristotle, the purpose of the state was to enable its citizens to live a good life, and justice was the key virtue for achieving this. He further analysed justice into different types, such as distributive justice (concerning the fair allocation of goods and honours) and corrective justice (concerning the righting of wrongs), laying the groundwork for later legal theory (Miller, 1995). For both Plato and Aristotle, natural justice was discoverable through human reason and was seen as the foundation for a well-ordered political life.
## The Medieval Transformation
The ideas of the classical philosophers, particularly Aristotle, were preserved and transmitted through the Roman period and into the Middle Ages, where they were profoundly reshaped by the rise of Christianity. While Roman thinkers like Cicero had already articulated a concept of a universal “true law” which is “right reason in agreement with nature,” it was medieval theologians who integrated this tradition into a comprehensive divine framework (D’Entrèves, 1970).
The most influential figure in this synthesis was St. Thomas Aquinas in the 13th century. Drawing heavily on Aristotle, whom he referred to as “the Philosopher,” Aquinas developed a systematic theory of law in his *Summa Theologiae*. He proposed a hierarchy of four types of law: Eternal Law, Natural Law, Divine Law, and Human Law. The Eternal Law is God’s rational plan for the entire universe, a plan that is beyond complete human comprehension. Natural Law is humanity’s participation in this Eternal Law. As rational creatures, humans have a natural inclination to do good and avoid evil, and through reason, they can discern the fundamental principles of God’s plan for them. As Aquinas states, the first precept of natural law is that “good is to be done and pursued, and evil is to be avoided” (Aquinas, 1947, Part I-II, Q.94, Art.2).
From this primary precept, other more specific principles are derived, corresponding to basic human goods: the inclination to preserve one’s own life, to procreate and raise offspring, to know the truth about God, and to live in society. These principles are universal and unchanging because they are based on the human nature created by God. Human Law, or the positive laws of the state, must be based on this natural law to be just and legitimate. Aquinas, following St. Augustine, argued that a human law that conflicts with natural law is not a true law but a “perversion of law” and does not have binding force in conscience. Therefore, in the medieval conception, natural justice is not simply a product of philosophical reason observing nature, but an expression of divine reason that provides a moral compass for all human legislation. The ultimate source of justice is no longer an impersonal Form of the Good or the *telos* of the community, but the will and reason of a personal God.
## Conclusion
In summary, the classical and medieval conceptions of natural justice both share the fundamental belief that there are objective moral standards that transcend human convention and provide a basis for law and politics. The main features of the classical view, developed by Plato and Aristotle, were that justice is a form of natural order, discoverable through reason, and linked to the proper functioning of the human soul and the political community. Plato located this standard in a metaphysical realm of Forms, while Aristotle found it embedded in the nature and purpose of human life. The medieval conception, exemplified by Thomas Aquinas, adopted this framework but transformed it by placing it within a Christian theological context. Natural justice became a participation in God’s divine plan for the cosmos, with its principles flowing from God’s Eternal Law and being accessible to human reason. While building on classical foundations, the medieval view thus shifted the ultimate justification for natural justice from pure reason and nature to divine reason and creation, a development that profoundly shaped the subsequent history of Western political and legal thought.
## References
- Aquinas, T. (1947) Summa Theologiae. (Trans. Fathers of the English Dominican Province). Benziger Bros.
- Aristotle (2004) The Nicomachean Ethics. (Trans. J. A. K. Thomson). Penguin Classics.
- D’Entrèves, A. P. (1970) Natural Law: An Introduction to Legal Philosophy. 2nd ed. Hutchinson University Library.
- Miller, F. (1995) Nature, Justice, and Rights in Aristotle’s Politics. Oxford University Press.
- Plato (2007) The Republic. (Trans. D. Lee). Penguin Classics.
- Sabine, G. H. and Thorson, T. L. (1973) A History of Political Theory. 4th ed. Dryden Press.
