Cicero described natural law as the "right reason in agreement with nature of universal application, unchanging and everlasting." A fundamental part of natural law is the existence of absolute and unchanging values of right and wrong. In the world of business, priorities are constantly changing: there is no set purpose for businesses that underpins their existence. As a result, it can be claimed that natural moral law cannot be applied to issues of business ethics. On a different note, natural moral law is very much concerned with good, evil and the role of human reason in distinguishing between the two. Business ethics does not often involve clear cut decisions between right and wrong; more often than not businesses are concerned with balancing the interests of shareholders, with those of employees and customers. Therefore, it can be maintained that the absolute principles of natural moral law are not useful when applied to the complex issues raised by business ethics.
Both the Aristotelian and Thomist forms of natural moral law are concerned with human purpose as a whole. Aristotle believed that the goal of every human was to achieve "eudaimonia," or all-round flourishing as a human being. Aquinas, on the other hand related his ideas of purpose to the Christian beliefs of achieving unison with God and receiving beatific vision. From such a viewpoint, Aquinas deduced five primary precepts that he felt needed to be adhered to in order to "do good and avoid evil." These were self-preservation, reproduction, education, living in society, and worshipping God. It is the narrow nature of these precepts that present one of the initial problems encountered when applying natural moral law to business ethics. Most businesses do not aim to fulfil the "human purpose," "they have been established as a means of providing a service that generates profit." If businesses were forced to create secondary precepts that promote such particular fulfilments as the worship of God, it would mean going to unnecessary and costly lengths that would not yield financial reward.