Selection from An Introduction to Philosophy | Daniel J. Sullivan

(Rockford, IL: TAN Books and Publishers, 1992), 67-69.

The doctrine of intentional existence gives us the solution of Aristotle and St. Thomas to what has come to be called in the history of philosophy the problem of universals. The answer to the question, What is the nature of ideas? is one of the most important and revealing that can be asked of any philosopher, for it is the key not only to what he holds about the nature of thought but also to his teaching on man and the universe. Philosophies can be classified according to their answer to this question, although the modifications of the basic positions are innumerable.

1. Moderate Realism

The view of philosophers in the tradition of Aristotle and St. Thomas is that what is known exists as universal in the intellect, but as individual outside the mind. This position is called Moderate Realism. It is called realism because the universals really do exist in the intellect; moderate, because their existence stops there. Since the form universalized in the intellect is identical with the form individuated in the thing, we can say, following the traditional formula, that our ideas are universal in the intellect only, but have a foundation in things.

Implied in this view of the nature of the idea is the spirituality of the intellect (otherwise the universal could not exist there) and the matter and form composition of all corporeal substances, including man.

2. Absolute Realism

The position of Plato and his followers, where the universals are real things existing by themselves, is called Absolute Realism, because the universals have a real existence in themselves. This doctrine is also termed Platonic Realism. Some of those who disagree with the position call it also Exaggerated Realism or Extreme Realism because they believe that it gives too much reality to the ideas.

This view implies a radical separation between the world of ideas and the world of bodies. According to it, man is a soul imprisoned in a body, or else soul and body are two separate substances. Reality is referred so exclusively to the ideas that the world of bodies is an indigestible fact of else it is dismissed as illusion.

3. Conceptualism

A modification of the Absolute Realist doctrine is found in the German philosopher Kant and his disciples. Rather than maintaining that the idea of universal is a spiritual reality existing independently of man, the same whether or not man exists at all, Kant placed the universal idea in the mind as a "form or category," a structural necessity of thought itself, a kind of mold into which our thoughts are cast. Thus we must think things as though they were universal, but this is due solely to the way the mind is constructed, and there is no relation of the idea to whatever may be outside the mind. Since universals exist as mental concepts only, this doctrine is given the name Conceptualism.

The nature of the outside world, the "thing-in-itself," is unknowable for the conceptualist, since what comes into the mind is re-cast according to the configuration of the mind itself. The end product of this constructive activity of the mind is called the phenomenon. The unknowable "something" outside mind is called the noumenon. Some of Kant's followers went beyond him and said that there is nothing whatever outside the mind itself. They are called Idealists, since they reduce all reality to the nature of mind and idea.

4. Nominalism

It is possible, finally to deny that there are any universals at all, either in the mind or outside the mind. What we call ideas are simply sense impressions. This position is called Nominalism The name comes from an eleventh-century philosopher called Roscelin who said that ideas are just names (nomina), "puffs of breath," standing for nothing.

Since there are only sensations and no ideas, the nominalist is forced to admit only one kind of reality. Either he is a Materialist, and admits the existence of bodies only, or he is an Idealist, who says that what we call sensations are mental modifications, which along with mind constitute the whole of reality.