Thomas Aquinas/Natural Law

Natural Law

Moral principles rooted in human nature and knowable through reason. It directs humans toward what is good and away from what is evil.

First Precept of Natural Law

The most basic moral principle: “Good is to be done and pursued, and evil is to be avoided.” All other natural-law precepts are based on this.

Precept

A rule or command directing action. Aquinas says natural law has many precepts, even though they all come from one foundational principle.

Practical Reason

Reason concerned with what we should do. It guides action and identifies things as good to pursue or evil to avoid.

Speculative Reason

Reason concerned with what is true rather than what should be done. Aquinas compares its basic principles to the basic principles of practical reason.

Self-Evident Principle

A principle whose truth is contained in the meaning of its terms. Some principles are obvious to everyone, while others are obvious only to people who understand the concepts involved.

Self-Evident in Itself

A statement is necessarily true because of the relationship between its subject and predicate, even if a particular person does not recognize it.

Self-Evident to Us

A truth that a person can immediately recognize because they understand the concepts involved.

First Principle

A basic starting point for reasoning that is not derived from a more fundamental principle.

Good

In practical reasoning, that which is sought or pursued as an end. Aquinas says every agent acts toward something understood as good.

End

The goal or purpose toward which an action is directed. Aquinas says good has the character of an end.

Natural Inclination

A built-in tendency of human nature toward certain goods. Aquinas thinks these inclinations help reveal the precepts of natural law.

Inclination to Self-Preservation

Humans naturally seek to preserve their own existence. Therefore, things that protect human life belong to natural law.

Inclinations Shared with Animals

Human tendencies connected with animal nature, such as sexual reproduction and the care or education of offspring.

Inclinations Proper to Rational Humans

Specifically human tendencies connected to reason, such as seeking truth, knowing God, avoiding ignorance, and living peacefully in society.

Order of Natural Inclinations

Aquinas says the order of natural-law precepts corresponds to the order of human inclinations: preservation of life, animal goods, then rational and social goods.

Concupiscible Faculty

The part of appetite connected with ordinary desires and aversions, especially pleasures and pains. Aquinas says such inclinations belong to natural law insofar as they are governed by reason.

Irascible Faculty

The part of appetite connected with difficult goals, obstacles, fear, anger, hope, and similar responses. It too must be ruled by reason.

Reason Governing Inclination

A natural desire is not automatically morally correct. Aquinas says human inclinations must be ordered and directed by reason.

One Natural Law, Many Precepts

Natural law is one because all its rules come from one foundational principle, but it contains many particular precepts.

Universality of Natural Law

The most general principles of natural law are the same for all human beings.

General Principles

Broad principles that apply universally, such as acting according to reason or pursuing good and avoiding evil.

Particular Conclusions

More specific rules derived from general principles. These may admit exceptions when circumstances change.

Practical Rectitude

Moral rightness or correctness in action. Aquinas distinguishes whether something is objectively right from whether people recognize it as right.

Knowledge vs. Rectitude

Something can be objectively right even if some people do not know or recognize that it is right.

Necessary Things

Things that cannot be otherwise. Aquinas associates speculative reasoning more closely with necessary truths.

Contingent Things

Things that could be otherwise and depend on circumstances. Human actions are contingent, so practical reasoning often has to consider particular situations.

Common to All vs. Detailed Cases

General moral principles are universal, but the more specific a situation becomes, the more exceptions or complications may arise.

Entrusted Goods Example

Normally, property entrusted to someone should be returned. But if returning it would cause serious harm, the general rule may not apply in the same way. Aquinas uses this to show that circumstances matter.

Role of Circumstances

Circumstances can affect how a universal moral principle should be applied in a concrete case.

Reasons for Moral Error

Aquinas says people may fail to recognize natural-law conclusions because of passion, bad habits, or a badly formed disposition.

Passion

Strong appetite or emotion that can interfere with proper reasoning and distort moral judgment.

Habit

A repeated pattern or disposition. Aquinas says bad habits can make a person misunderstand or ignore what natural law requires.

Reason as the Human Standard

Although individuals have different desires, natural law is not based simply on whatever a person happens to want. Human inclinations should be directed according to reason.

Main Idea of Article 2

Natural law contains many precepts, but they all come from one first principle: pursue good and avoid evil.

Main Idea of Article 4

Natural law is universal in its general principles, but specific applications can vary because practical situations and circumstances differ.