what is reality?

[Thriller]

No, it depends on what you mean by "mind". You stated that reality only exists in the mind. Using the same meaning of mind, I asked you where the mind exists, implying that it cannot only exist within itself, as without its existence, it can neither contain nor conceive its existence. In other words, the mind must actually exist, as opposed to subjectively exist.

I've already concluded that not all reality is subjective. There are two realities.

To reformulate what I said before: one reality is subject to perception and belief: subjective/perceived reality.

The other one is what actually exists, but this one is unknowable, except to a very limited extent through reason. I call this second reality "actual reality". I can prove that it exists by stating that I am thinking and therefore my thoughts actually exist. My thoughts, however, must also be conceived, and that which conceived them must also actually exist.

Cogito ergo sum... the problem with that is that the argument presuposes ones own existence

x thinks
i am that x
therefore i think
therefore i am

the argument is syllogistic

[agapooka]

And the presupposition that he presupposed his existence presupposes that he existed to presuppose his existence.

Actually, what he did was quite within reason. He realised that he thought and that implied, perhaps among other things, his existence. Is there a theoretical alternative of what it could imply? Furthermore, he never stated what he is.

I see what you're getting at in a way - one of his premises implies his conclusion, yet can his premise be denied? Can you deny that he thought? Whence, then, come his premise and conclusion, if they were not the object of thought?

Yes, perhaps you can deny that he thought, actually. The question is, can you doubt or deny that you think? Can I doubt or deny that I think? And if I doubt or deny that I think, must I not exist to doubt or deny it?

But I have convinced myself that there is absolutely nothing in the world, no sky, no earth, no minds, no bodies. Does it now follow that I too do not exist? No. If I convinced myself of something [or thought anything at all] then I certainly existed. But there is a deceiver of supreme power and cunning who is deliberately and constantly deceiving me. In that case I too undoubtedly exist, if he is deceiving me; and let him deceive me as much as he can, he will never bring it about that I am nothing so long as I think that I am something. So, after considering everything very thoroughly, I must finally conclude that the proposition, I am, I exist, is necessarily true whenever it is put forward by me or conceived in my mind. (AT VII 25; CSM II 16–17)

EDIT: I see you used Kierkegaard's critique to the letter.