Thomas Aquinas's Summa Theologica: Ethics and Natural Law

Thomas Aquinas and Scholastic Thought

This text analyzes key concepts from The Summa Theologica, one of the major works of Saint Thomas Aquinas (ST), the central figure in Christian scholastic thought.

Teleological Ethics and the Pursuit of Beatitude

Aquinas’s ethics, perhaps the highlight of his philosophy, incorporates the profound influence of Aristotle. His teleological ethics posits a vision where the greatest happiness is the ultimate end of life. ST argues that maximum happiness is achieved through the contemplation of God. Human life is directed toward this contemplation—the path of perfection, since God is perfect—leading to the Beatific Vision (union with God).

If life has a final end, humans also possess this end. This final purpose allows humans to derive moral principles (unlike other creatures) by making use of reasoning and understanding.

The Principles of Natural Law

These derived principles constitute the Natural Law, which Aquinas defines as:

• Obvious: Known by all.
• Universal: Applies to everyone.
• Mandatory: Binding for all.
• Immutable: Unchanging, as it is based on immutable human nature.

General Principles and Precepts

Natural Law contains two general principles: Do good and avoid evil. All subsequent moral actions must align directly with nature and reason.

Natural Law further contains three levels of precepts:

1. Substantial (or Primary): Basic principles concerning the conservation of life and self-preservation.
2. Animal: Rights related to procreation and the care of offspring.
3. Human: Implies the search for truth and justice, often achieved through God.

Society, State, and Political Philosophy

Apart from the contemplation of God, man, by nature, tends to live in society, echoing Aristotle’s view. Aquinas recognizes that the state is beneficial because society helps develop the individual.

Aquinas vs. Augustine on the State

In this view, Aquinas separates himself from Saint Augustine, who argued that society and the state were consequences of sin and malice. Aquinas affirms that the state helps make us good, and since man is sociable by nature, and nature was created by God, government and rulers were also created by God.

Aquinas advocates for a middle class of rulers, where the best individuals govern and seek the common good. However, he asserts that the power of the Pope is above all others.

He states that there are two ultimate ends for humanity: the vision of God (spiritual) and the temporal good (earthly), unlike Aristotle, who separated the spiritual from the territorial/political sphere.

Finally, Aquinas establishes a relationship between Church and State (faith and reason), placing the spiritual realm above the temporal.

Hylomorphism and the Immortal Soul

ST defends the doctrine of Hylomorphism (the unity of matter and form) in human beings, thereby avoiding dualism.

ST maintains that when a person dies, death breaks this unity. Since the soul is immortal, it remains separated from the body until the resurrection. In this specific context, Aquinas agrees with Plato (regarding the immortal soul) and Aristotle (in the sense that the soul initially leaves the body, though Aquinas rejects reincarnation).