The common good is a term that can refer to several different concepts. In the popular meaning, the common good describes a specific "good" that is shared and beneficial for all (or most) members of a given community. This is also how the common good is broadly defined in philosophy, ethics, and political science. However, in economics, the term "common good" is used to refer to a competitive non-excludable good.

Common good in philosophy, ethics and political science

In ethics and political science, to promote the common good means to benefit members of society. Thus, in essence, helping the common good equates helping all people, or at least the vast majority of them. In that sense, the term could be synonymous with the general welfare.

However, there is no strict definition of the common good for each situation. The good that is common between person A and person B, for example, may not be the same as between person A and person C. Thus, the common good can often change, although there are some things (such as the basic requirements for staying alive: food, drinking water, shelter, etc.) that are always good for all people.

The common good is often regarded as a utilitarian ideal, thus representing "the greatest possible good for the greatest possible number of individuals". In the best case scenario, the "greatest possible number of individuals" would mean all individuals.

Some assert that promoting the common good is the goal of democracy (in the sphere of politics) and socialism (in the sphere of economics).

Common good in economics

One of the most common ways of looking at goods in economics, illustrated in the table below, is the classic division based on:

• whether there is competition involved in obtaining a given good
• whether it is possible to exclude a person from consumption of a given good

Sometimes, club and common goods are included in the broad definition of public goods. There are always some goods that can be argued to belong in more than one of the above categories.

Common goods should not be confused with another subtype of public goods: the collective goods (also known as social goods), which are defined as goods that could be delivered as private goods, but are delivered instead by the government for various reasons (usually social policy).