Thread ID: 11 At 4/1/2008 6:20:06 PM Alistair wrote:

Could you point me to a working definition or a scientific definition of the Common Good.


Mike Augros Answers
There are five sciences that consider common goods: the three parts of practical philosophy (i.e. individual ethics, domestic philosophy, and political philosophy), and two of the ‘theoretical’ sciences, namely metaphysics, and to a lesser extent, the philosophy of nature.

In the three parts of practical philosophy, one must consider the goods which friends have in common, or which members of a family have in common, or which fellow citizens have in common, and these are all common goods of one kind or another.

And some particular branches of natural philosophy must discuss the goods which the members of a species of animal or plant have in common, or the goods which different species, living together, have in common.

And metaphysics must discuss the goods which all things in the universe have in common.

There will be considerations of specific kinds of common goods, then, in each of these disciplines. Nonetheless, it is possible to give some general definitions of “common good” which apply more or less in every one of those sciences.


To understand “common good,” we must understand the terms “common” and “good.”


“Good” in general means “what perfects (or completes) something by fulfilling some desire.” An agent cause also perfects or completes something, and so does a formal cause, but we call a thing “good” because it perfects or fulfills something in being the object of its desire. This definition is through the proper effect of goodness, not through what makes a thing to be good. And although we may desire bad things, this is incidental to their badness, since we can desire them only insofar as there is something good in them, or insofar as we mistake them for something else that is good. Hence the good alone is as such an object of desire.


To understand “common good” we must distinguish two senses of “common” (or “general” or “universal”) (see Thomas Aquinas’s De Veritate Q7 A6 Ad2). Something may be “common” either in predication or in causation.

1. Common in predication. If one thing is said of many things, it is “common” to them in this sense. For example, “man” is said of both this man and that one, so “man” is an attribute common to both.

2. Common in causation. If one individual thing is the cause of many effects (at the same time and especially by one kind of causation or even one act), it is a “common” cause, a cause “common” to many effects. A cause especially deserves to be called a “universal cause” when it is not only a single individual causing many things at once, but when the many things it causes all have something in common—in other words, when the cause is responsible for something which is universal or common in predication.

For example, is God “common” or “universal”? Not in predication, since “God” (meaning the creator) is not said of many different things. But he is a universal cause, since he is the cause of being in all things. (One might say that a universal cause is an individual thing which is the cause of a universal attribute.)

And is “man” or “cat” common? Yes in predication, since these are each said of many things. But not in causation, because neither of them names a single individual thing.


When we speak of a “common good,” we might have in mind a good that is common in predication, for example, “health.” That is something good for everyone. But there is no single health out there which makes all of us healthy. We each have our own health.

So what if some goods are such that they can be a single individual, yet benefit many different individuals at the same time? That would be a special kind of good indeed, and would deserve a speical name. Such a good would be “common” in the sense of being common in causation, not predication (since it is one individual thing). It is especially in that sense that “common good” is meant (e.g. by Plato, Aristotle, Thomas Aquinas etc.).

DEFINITION: “common good” means a good one in number that is able to be shared by many individuals. (Summa I-II Q90 A2 Ad2)


Some common goods can be shared by many individuals more perfectly than others.

For example, the Pythagorean Theorem is a single truth that can perfect the minds of many different people all at the same time, without any decrease in its power to perfect people’s minds. So that truth is a common good.

And the Eucharist can be shared by many different people at the same time, without any diminishing of Christ himself, or in his power to sanctify us. (The miraculous multiplication of the loaves in part signifies this inexhaustibility of the divine goodness.)

But sometimes a common good can be shared by many people at the same time, but not without lessening. For example, my family can share the same pizza at the same time, but not without diminishing the pizza. Nor is it exactly the same good we share; although it is one and the same pizza, we each take a different part of it.

Other times a common good can be shared without any diminishing of it, and it is the very same good which is shared by many individuals, but they cannot use or enjoy it at the same time. A public parking space, a library book, or a park bench are examples of such common goods.

So one might say that a perfect common good, in the strictest possible sense, means a good one in number that can be shared by many individuals at the same time without any diminishing of that good.

On the other hand, an imperfect common good would mean a common good that can be shared by many individuals without diminishing, but not at the same time—or else a good that can be shared by many at the same time, but not without diminishing.


By contrast, a “private good” is one which is somehow unable to be shared by many, being ordered to one individual alone.

Some private goods cannot be shared at all. For example, my act of understanding the truth, as such, is mine and mine alone, and while I might cause someone else to understand the same truth, I do not really give him my understanding of it. That is an incommunicable good. No one else can have my act of understanding; no one else understands by my act of understanding.

Other private goods cannot rightly be shared, e.g. my wife, as a wife, is mine alone and cannot rightly be used as a wife by any other so long as I live.

Others in themselves are able to be shared to some extent, but have been justly appropriated by a single person, and a part of their goodness consists in their not being available to others, so that they will be more readily available to that single person. Private property is of this kind—like my shoes.

Sometimes what begins as a common good, when shared, is divided into private goods (and for that reason is diminished). For instance, I bring home a pizza for the family, and it is a common good, meant to be shared by everyone. But when I take a slice of it for myself, it becomes my private good, which is not meant to be shared by many individuals.

DEFINITION: a “private good” means a good one in number that is (for whatever reason) not able to be shared by many individuals.


Without even descending into specific kinds of common goods, one can note several important differences among common goods:

A. Perfect and imperfect. As just noted above, some common goods are able to be shared by many at once without diminishing. Others only at different times, or only with some diminishing.

B. Immaterial and material. Some common goods are immaterial, like the truth of the Pythagorean Theorem; others are material, like a pizza for the whole family. This distinction goes more or less hand in hand with the first distinction. More immaterial goods tend to be more communicable without diminishing; more material ones, because of their existence in place, must be divided to be shared, either in time or place.

C. Formal and non-formal. Sometimes a common good is like the very union of the individuals who benefit from it, forming them into some kind of community which it benefits each one to be a member of. One might call that an “intrinsic” or “constitutive” or “formal” common good. Other times, a common good is something beyond the form constituting some community, and is the further good for the sake of which that community forms in the first place. For example, the order within the soldiers of the army is good for every soldier in it, so that is a common good of the army that is intrinsic to it and forms it. But victory over the enemy is also good for each soldier, and that is a common good of the army which is outside it, and does not form the army, but presupposes the army already formed. And the order within the army exists for the sake of victory: the intrinsic common good of a group or society or association is for the sake of some good other than the formation of that society and for the sake of which that society is formed. Again, the order of distinct roles of the members of an orchestra or of a basketball team is a common good for the orchestra or basketball team. That kind of unity or harmony is precisely what makes the members to be an orchestra or a basketball team in the first place. Beyond that, there is a common piece of music, or a common victory, for the sake of which they cooperate.

D. Arising out of singular goods, and not arising. Sometimes a common good arises out of many single goods taken together in some way. For example, the order in the parts of an army consists in the right relation between this one and that one. Also the common good of victory arises out of this soldier killing his man, that soldier killing his man, etc. The common good of victory arises out of these particular victories. But God is a common good which in no way arises out of any particular goods.


One may of course distinguish particular kinds of common goods, too. For example, there are the common goods of the members of the universe, namely the order of the universe, and God, to which they are all ordered. And there are common goods for each species of animal, such as the preservation of that species by reproduction. And there are the common goods of a human society such as a city or a family. The city reservoir is a common good of the citizens; the public library is another; safe streets is another; a justice system to which citizens may all have recourse is still another. And the family car or family house are common goods for all the members of a family, and each member of the family is also a common good for all the other members. My wife and I both benefit from having a new child in our lives, and our other children all benefit from having a new sibling—all at the same time, and without diminishing that good by sharing it. It is the business of the sciences to study all these particular goods, and the order among them.


When people speak of “the” common good, they are speaking by the figure of speech called antonomasia. That is when we give a general name to a specific instance which stands out. Hence we speak of “the good book” not because the Bible is the only good book, but because it is THE good book. And we speak similarly of St. Paul as “the Apostle,” and of Shakespeare as “the Bard,” and of Aristotle as “the Philosopher,” and so on.

In human affairs, which common good stands out? The one that benefits the most people, namely the common good of a whole city or nation (or even the whole world). But even a city or nation has many common goods, not just one—so what is meant by “the” common good? What is meant is the whole orderly aggregate of common goods for the city or nation, the whole good of the whole. This is a case of a common good arising out of many particular common goods. This is usually what people mean by the phrase “the common good,” and usually what the Catholic Church means when she employs it:

By common good is to be understood “the sum total of social conditions which allow people, either as groups or as individuals, to reach their fulfillment more fully and more easily” ... (CCC nn 1906-1910)

One final note:

Many people mistakenly oppose “the common good” and “the good of the individual.”

Perhaps we could reasonably call a private good a “good of the individual,” since an individual’s private goods are more his property than any common good can be.

But many people have the false idea that a “common good” is not a good for the individual, but is good only for some collection or multitude as a collection or multitude, and does not actually benefit the individuals in it.

In what sense would that be “good”? For whom would it be good? For no one, if not for individual people—and hence it would not really be a common good as it was defined above.

A common good, remember, is one that can benefit many individuals at the same time. Why would one good be able to do that, whereas others, “private” goods, cannot? Because some goods are greater, more intense, more divine, more perfect, and hence can benefit more people than others can. Within one and the same order, therefore, any common good benefits an individual more than any of his private goods. For example, the existence of the U.S. is a greater good for me as an individual than my own house or car; it would be a greater loss for me if the U.S. were destroyed than if my house and car were destroyed. Again, since I am a social being, and am perfected most of all by living a life in common with others, the goods which make a human community possible are greater goods for me than those which benefit me alone. For example, I benefit more from the existence of a public food and water supply than I do from my own private food and water supply. The common source is the cause not only of my own private share, but also of the share of many others, which makes it possible for me to live with many others, with all the further goods that implies.

It is a mistake, then, to think that since a private good is good for an individual, a common good must not be good for any individual. The truth is that both private goods and common goods are goods for individuals. The difference is that a private good is good for only one individual, whereas a common good is good for many.

Another reason for the error is that “common good” has in recent times been used to mean something like “the good of the collective” as opposed to the good of any individuals. What does this mean? What does it mean for something to be “good” for the whole society but which in no way benefits any of the individuals in it?

In such a case, the “good” obviously does not answer to any desire within the society itself. Then the desire it satisfies is outside it, i.e. in the maker and shaper of it, like the Marxist philosopher, or the Socialist totalitarian, who wants to shape all of society according to his own wishes. The Marxist (we might imagine) looked down upon the collective which he had fashioned just as he wished it to be, in which all the members were miserable but were doing what they were supposed to, “and he saw that it was good”—where “good” means “made in the image and likeness of the totalitarian,” conformed to his thought, expressing it, like a great work of art. The members of his work of art want this or that, but who cares about that? The poor fools don’t know what they want, or rather, what they want does not matter; what matters is the will of the artist!