The word good is the most general positive evaluation that can be used in a wide range of contexts. It is used to indicate that something has some positive attribute: “the soup was very good.” It can be used to describe an experience, a job, or anything else: “that was a really good book.” It is also an evaluative term: “That sounds like a great idea!”
The concept of the good has been central to moral deliberation for as long as there have been philosophers. There are many ways to approach the problem of defining the good, and it has been a source of disagreement.
For example, some philosophers have distinguished between attributive and predicative uses of the term. Geach, for instance, argued that the adverb good is always attributive; something only has the attribute “good” when it can be attributed to it. The predicative use of the term, on the other hand, corresponds roughly to the notion of value: a knife is valuable, for instance, but we can still argue about whether or not it’s good.
There is another, more important distinction that has been made about the good. Some philosophers have sought to define the good in terms of an object or activity. Others, most notably Aristotle and Immanuel Kant, have defined the good in terms of human flourishing or perfection. For Aristotle, the good life is a life of excellence, and to excel requires not just pleasure but the exercise of reason: the ability to think about what one should do and the motivation to do it.
Aristotle’s conception of the good has had a profound impact on subsequent philosophical thinking. Among other things, it influenced the Enlightenment discussions of “the good, the true, and the beautiful” in Kant’s Critique of Practical Reason. Aristotle’s view that the good life is the flourishing of reason was also influential on religious and philosophical schools that tended toward hedonism, such as the Epicureans.
Regardless of which stance is taken, the idea that there is a good is at the heart of most ethical theories. It is also at the center of much of philosophical literature and discourse.