The polemic of one and many (unity and diversity) has become the matter of philosophy since the age of the early Greek philosophy. For example, Thales maintains the unity when he says that the substance of the universe is water. This opinion has been rejected by Empedocles and Anaxagoras who stresses on the diversity by saying that there are some or many substances in the universe. Another philosopher, Parmenides, think about the unity when he says that the existence must be one and there are no other things that exist. However, Heraclitus declines this opinion when he describes that all sensible things are always in a state of flux and there is no knowledge about them.
A few centuries later, Plato teaches about the unity in the world of idea and plurality in the world of matter. Yet, Aristotle, Plato’s student, speaks against this distinction. He says, “… it must be held to be impossible that the substance and that of which it is the substance should exist apart; how, therefore, can the Ideas, being the substances of things, exist apart?”
With the advent of the enlightenment era which enhances the significance of human ratio, the pursuing of the objective and universal truth has become the main effort in the entire investigation of modern philosophy and therefore the unity has become a big theme. However, postmodernism today declines the unity and elevates the diversity, and for this reason its philosophers reject all modernism endeavors to gain universal and objective truth. For instance, Derida expresses his rejection when he says, “What is really going on things, what is really happening, is always to come. Every time you try to stabilize the meaning of a thing, to fix it in its missionary position, the thing itself, if there is anything at all to it, slips away.”
To give a Christian response to this problem Van Til in "The Defense of the Faith" describes:
In seeking for an answer to the one and many question, philosophers have admittedly experienced great difficulty. The many must be brought into contact with one another. But how do we know that they can be brought into contact with one another? How do we know that the many do not simply exist as unrelated particulars? The answer given is that in such a case we should know nothing of them; they would be abstracted from the body of knowledge that we have; they would be abstract particulars. On the other hand, how is it possible that we should obtain a unity that does not destroy the particulars? We seem to get our unity by generalizing, by abstracting from the particulars in order to include them into larger unities. If we keep up this process of generalization till we exclude all particulars, granted they can all be excluded, have we then not stripped these particulars of their particularity? Have we then obtained anything but an abstract universal?
According to him, only in the doctrine of the Trinity people can find a real solution because in it people can actually have a concrete universal, that is, in the being of God, all particulars relate to universal where the universal is fully expressed in the particulars. To put Van Til’s view another way, in the Trinity the concept of one does not exist in abstract universal just as philosophers view (e.g. Plato with his world of idea) but in the being of God and therefore we find a concrete universal. Moreover, the being of God is fully expressed in its particulars (in the three persons). Consequently, Christians really have a concrete one and many in the being and the persons of God.
