On the Essence of Law

"There was a scholar of the law who stood up to test him and said, "Teacher, what must I do to inherit eternal life?"
Jesus said to him, "What is written in the law? How do you read it?"
He said in reply, "You shall love the Lord, your God, with all your heart, with all your being, with all your strength, and with all your mind, and your neighbor as yourself."He replied to him, "You have answered correctly; do this and you will live." Luke 10:25-28


The concept of law is an important element of moral philosophy, for it is by an understanding of law that we hope to better understand how we ought to act. We are guided in our actions by a system of law.

But the law discussed by Aquinas goes well beyond the written laws of society. When we refer in everyday conversation to law, we typically are referring to the law written by governments ? the law we must obey to stay out of jail. Yet, that is only one of four types of law discussed by Aquinas ? the human law.

As Christians, we hold ourselves to a higher standard. To lead a truly good and moral life, one must do more than obey the written laws of society. Indeed, in the scripture passage above, reference is made to God and to love: neither of which appears much in the written laws of the state.

We strive to adhere to greater principles of law. Those principles are found in the other three types of law ? eternal, natural, and divine. I must add that these types of law are not exclusively the responsibility of Christians, but of all men. There is right and wrong, regardless of the modern day tendency to say such things are subjective.

The definition of law

Aquinas defines law as "a rule and measure of acts, whereby man is induced to act or is restrained from acting." Lex (Latin for law), he points out, is derived from ligare meaning "to bind." (Summa Theologica First of the Second Part, Q. 90, Art. 1)

Laws are rules meant to bind individuals to certain actions. The speed limit, for example, is intended to hold drivers within a certain acceptable speed. Drivers are bound to this by police officers and the threat of fines or arrest.

Law and reason

Furthermore, law is derived from reason:

"Now the rule and measure of human acts is the reason, which is the first principle of human acts, as is evident from what has been stated above. For it belongs to the reason to direct to the end, which is the first principle in all matters of action, according to the Philosopher [Aristotle]." (ibid.)

The idea that reason is the rule of human actions comes from Aristotle?s Nicomachean Ethics. In the first sentence, Aristotle argues that all actions are "thought to aim at some good." Aquinas uses this idea to explain human actions. Essentially, actions are taken for some purpose or end. That end is expected to be good, because if it was not, the action would not have been taken.

If I pick up an orange, I do so because I feel that picking up the orange is good. If I have no desire to pick up the orange, if I feel that picking up the orange would be a bad thing to do, I would not do so. This assumes that I am, first, acting according to reason and not out of emotion, and, second, knowledgeable of the action and the circumstances revolving around it, and, third, free to act as I wish. (Aquinas argues that only voluntary actions are subject to moral judgement.)

Therefore, since actions are taken according to reason, that which guides actions also must be taken according to reason.

A further note on reason and law

Defense tactics in criminal courts of law can be used to explain this point further. In cases where there is no doubt that the accused committed the act he is accused of, it is common for defense attorneys to defend their client by pleading insanity or temporary insanity (the crime of passion); arguing that the accused was not aware of what was going on; or that the defendant was in fact not acting voluntarily, but was forced into action by someone else or other circumstances.

The attorney in such cases hopes to convince the jury that if his client had not been overtaken by passion, had been knowledgeable of what was he was doing, and been free to act as he wished, then no crime would have been committed. That is, the person would have acted according to reason and within the bounds of law.

Law and the common good

Law is always intended to benefit the common good, for law is directed to the happiness of the individual. This seems to be contradictory, but it is not.

Law, first, is directed to happiness, since reason itself is directed to happiness. But, since the individual is a component of the society, law must be directed to universal happiness as well:

Moreover, since every part is ordained to the whole as the imperfect to the perfect, and since one man is a part of the perfect community, law must needs concern itself properly with the order directed to universal happiness. Therefore, the Philosopher [Aristotle], in the above definition of legal matters, mentions both happiness and the body politic, since he says that we call those matters just which are adapted to produce and preserve happiness and its parts for the body politic. (ST First of the Second Part, Q. 90, Art. 2)

Final definition of law

Aquinas concludes his discussion of the essence of law with another definition:

"Law is nothing else than an ordinance of reason for the common good, promulgated by him who has the care of the community" (ST First of the Second Part, Q. 90, Art. 4)