When used in contexts other than ethics, good may refer to a general positive evaluation, or it may be a specific quality or attribute of something: good food; a good teacher; good health. In ethics, however, it has a special meaning. The most important function of the concept good is its role in a moral life: it is the standard against which all actions are measured. In addition to the evaluative meaning of good, some philosophers have developed theories about the nature of the good that are based on its attributive use.

The most common type of use of the word is a predicative one, where it is used to describe the characteristics or qualities of something: good food; a good friend; good grades; a good book. The predicative uses of good are especially common in ordinary speech and writing, while the attributive ones appear mainly in formal contexts, such as academic writing.

While attributive uses of good may have little relevance to a person’s practical decisions, they are important to the development of ethical theories. For example, some philosophers have tried to naturalize the notion of good by arguing that it is something that comes from within the human mind and resides in a kind of “moral intuition”. Others, such as Philippa Foot (2001), have taken a more pragmatic view and argued that there are many ways that a person may achieve or attain the good life.

For most people, the concept of good is largely intuitive. It is the basis for much of what they do and believe. They think about it when making decisions, they talk about it with their friends and family members, and they strive to live a good life.

Because of its innate meaning and intuitiveness, the notion of good is often used as a standard against which to compare and evaluate other things. It is the standard against which moralists measure their own deeds, for example, to determine whether they have done a good or bad deed. It is also the standard against which religious believers assess their relationship with God, for instance, in terms of how well they have obeyed His commandments and what reward He will give them when they die.

Although some philosophical schools of antiquity tended toward hedonism or perfectionism, the most common ethical theory was that the good life is one in which the human mind exercises its highest power. For example, Aristotle argued that the exercise of reason elevates humans above the level of other animals and is thus the standard against which all lives must be judged.