Instantiation principle

The instantiation principle is a concept in philosophy that states that if something has a property, then necessarily that "something" must exist. For it not to exist would be a property without an essence, which is impossible.

For example, an apple is red. Here, the apple is the essence and the property is red. The instantiation principle implies that it is meaningless to say that "the apple is red, but the apple doesn't exist". The apple "must" exist for it to be red.

Note that the apple doesn't have to "physically" exist - It can simply be a conception in one's mind. For instance, the statement "Pegasus has wings" has the same structure as the apple analogy, but in this case Pegasus is only an idea in one's mind. However, the instantiation principle holds: in order for Pegasus to have wings, Pegasus must exist (if only conceptually).

This appears to be a simple and straightforward concept, but it is the basis for many important questions in philosophy. For instance, historically it has been the crucial building block of Descartes's philosophy, which is summed up in the cogito ergo sum argument, which runs something like this:

:"I am thinking, therefore I exist"

"I am thinking" is taken true. If this is true, then thinking is a property of a thing. One cannot have "thinking" (the property) without a "thinking thing" (essence). Therefore, a thinking thing must exist, and this Descartes holds to be himself.

Hinduism

In the Vedanta school of Hindu philosophy, Ramanuja establishes tenets of Visishtadvaita based on the instantiation principle. He argues that "a contentless cognition is not possible" and that for identification of an object, attributes (property) is a must. He extends the same to justify that multiple attributes can exist in one substrate without mutually excluding each other.