mental substance

For many philosophers, this word or the phrase "mental substance" has a special meaning.

Descartes is famous for his Dualism of material and mental substances.

After a moment he thought of words whose mental substance he flung into the abyss: "I accept.

This is opposed to the materialists, who hold that what we normally think of as mental substance is ultimately physical matter (i.e., brains).

Mental substance is the idea held by dualists and idealists, that minds are made-up of non-physical substance.

Thomas Sergeant, Joseph Butler, and Thomas Reid reasserted a continuous mental substance as the basis of personal identity, and said that the Lockean continuity of self-consciousness made no sense without it.

So, since they claim to know the complete and final story about the nature of mental substance, it is incumbent on them to show that it is impossible for the same consciousness to be transferred from one substance to another.

Certainly, to repeat, the terms "subject" and "object" are not to be taken as carrying with them the Cartesian theory of a subject in the sense of a simple indivisible mental substance whose identity over time is primitive and irreducible.

The point is that, in instances of some sort of brain damage (e.g. caused by automobile accidents, drug abuse, pathological diseases, etc.), it is always the case that the mental substance and/or properties of the person are significantly changed or compromised.