A new twist on an old problem.

Traditional natural law theorists are sometimes accused of committing the naturalistic fallacy, since their arguments about good and evil (both natural and moral) are usually based on a theoretical grasp of a thing’s nature. Proponents of the so-called “New Natural Law Theory,” for instance, blame the traditional natural law theorists for attempting to “deduce” a list of goods from a theoretical grasp of a things nature. Complicated arguments usually ensue regarding the relationship between the practical and theoretical operations of reason.

Now I think the naturalistic fallacy is closely related to the devaluing of nature typical of modern thought. For pre-moderns like Plato, Aristotle, Augustine and Aquinas, on the other hand, nature is value laden, so that a theoretical grasp of a thing’s nature in some way entails knowledge of what is good for that thing.

I wish, however, to address this claim that traditional natural law starts with a theoretical grasp of a thing’s nature and then from it “deduces” what is good for that thing. Discussions with my colleague Joe Spoerl have led me to adopt the following position: One can’t deduce an “ought” from an “is”, but we do get an “is” from an “ought,” and we get an “ought not” from an “is.” In this blog entry I’ll briefly explain and defend this claim.

Let’s start with getting an “ought not” from an “is.” We ought not to do evil. Evil, as Augustine and many others argue, is a privation of a proper good. A good being “proper” or not depends on its relation to a thing’s essence. Proper goods belong to a thing in virtue of the thing’s essence. Hence, eye sight is a proper good of a frog, but not a proper good of a rock; the privation of sight, or blindness, is an evil that a frog can suffer, but a rock cannot. In light of this definition of evil, it follows that in order to recognize evil one must first start from a knowledge of a thing’s essence, for we can’t recognize a “privation” unless we first know the proper “completion.” The more we know a thing, the more we know its proper goods, and the more we are able to recognize the privation of those goods as evil.

This line of reasoning supports the claim that from a theoretical grasp of a thing’s essence or nature we actually can deduce what things are evil for it. For example, a theoretical grasp of human nature would include in it the notion of “rational;” hence, we can deduce that the privation of reason is an evil for the human being, and the willful privation of reason a moral evil. Knowledge of a thing’s nature is thus required in order to recognize a lack as an evil. What a thing “is” must be known before one recognizes what “ought not” to be the case with it.

Here, however, is an interesting twist: where as knowledge of a thing’s nature is prior to knowing what is evil for it, knowledge of what is good for a thing is prior to knowing its nature. This is because, as Aristotle says in the De Anima II, we know a thing’s nature in terms of its powers, a power in terms of its activity, and an activity in terms of the object to which it is directed. The object brings into act and there by perfects and make intelligible the otherwise latent and incomplete natural power of the substance. All of the powers of the soul, then, are known in terms of the objects to which they are directed and by which they are actualized: the power of vision, for example, is made known by colors; the power of hearing is made known by sounds. After experience and reflection on the relationship between a thing and its surrounding environment, we progress to judgments concerning certain objects as perfective of a thing – that is, we judge that object “x” is “perfective of” and hence “good for” that thing; and upon this judgment we infer that the thing is of such a kind as to have “x” as one of its goods.

A things nature is known in terms of the goods that perfect it. Knowledge of goods is in this a way prior to knowledge of a things essence. From this it is clear that one cannot start with a knowledge of the essence and go on to deduce what goods belong to it. Rather, we see what things are good for a thing, and thereby come to a knowledge of the thing’s nature.

In this way, I would agree that you cannot deduce an “ought” (good) from an “is” – no deduction that starts from a thing’s essence arrive at a good that was not previously known. But you can and do get an “is” (a theoretical understanding of a things nature) from an “ought.”

For the sake of brevity I’ve had to sacrifice a certain degree of precision. When the inadequacies are detected I hope that they can serve as the occasion for further discussion.