Q&A: Maimonides and the Principle of the Identity of Indiscernibles
Maimonides and the Principle of the Identity of Indiscernibles
Question
Hello Rabbi,
As I understand it, at the beginning of the Book of Knowledge, regarding the unity of God, Maimonides mentions that there cannot be two divinities, because if there were two, then there would have to be some property that differentiates and defines the boundary between them. But according to the Rabbi’s view, it is still possible that there could be 2 objects with exactly the same properties.
Also, I wanted to ask why the Rabbi thinks that the identity principle is in fact incorrect. Although I agree that there is no essential connection between an object’s properties and its existence, I still think that there cannot be two objects with the same properties, because one object would “override” the property of the other object. Of course, not every property is one-to-one (for example, beauty, strength, power, and so on), but there could be properties of that kind, such as the location of an object.
If there were many gods, they would be bodies and corporeal entities, because things that are counted and are equal in their existence are distinguished from one another only by the accidents that occur to bodies and corporeal entities. And if the Creator were a body or corporeal entity, He would have an end and limit, for it is impossible for there to be a body without an end. And everything whose body has an end and limit, its power too has an end and termination. But our God, blessed be His name, since His power has no end and does not cease—for the sphere revolves continually—His power is not the power of a body. And since He is not a body, the accidents of bodies do not occur to Him, such that He could be divided and separated from another; therefore it is impossible that He be anything but one. And the knowledge of this matter is a positive commandment, as it is said: The Lord our God, the Lord is one.
Answer
As for Maimonides, I don’t see any reference there to the principle of the identity of indiscernibles (he is speaking about the accidents that happen to bodies, not about their properties). He assumes that a material thing is necessarily finite and limited. Personally, I am not convinced by that assumption.
As for your question about the principle of the identity of indiscernibles, I really do not agree. I think I explained this in the piece “Two Wagons.” Location is not a problem. Two bodies can be in the same place. Bodies with mass do not allow one another to be there, but that is only a physical principle (they exert force on one another), not a logical one. There is no logical obstacle to there being two bodies in the same place with all their properties identical. For example, photons or physical particles called bosons can have exactly the same properties (including location). This is unlike the particles called fermions.