It is impossible to prove because mind is unreal.
Rene Descartes: John Searle, my argument is based upon my thoughts. I am thinking, so I exist. See, my thought or the process of thinking proves that I am real and I exist. Why you people consider mind and body as a single unit? How can you prove that mind and body are same? I can prove that mind and body are different entities. At the same time, mind and body influence each other.
Searle: We need not ponder upon the term ‘mind’ because it does not exist and it is unreal. Sir, you pointed out that mind and body influence each other. At the same time, why don’t you consider that mind is the part of body? I think the study of mind needs a satisfactory conclusion because we are arguing upon an imaginary thing without proof. When you say that the process of though proves the existence of mind, why can’t you say that the same process of thought proves that thought is an inseparable part of brain, which is real?
Descartes: For the sake of argument, please think that you do not exist in this world. You cannot prove your argument because you are real. From a different angle of view, your thought or argument is totally against your existence. To be specific, your argument that you are unreal (say, your imagination based upon your mind) proves that you are thinking. At the same time, you are totally aware of the fact that you are not unreal because your physical body is here. ...