After reading Descartes meditations, it seems clear: we can think, therefore there must be an ‘I.’ In other words, if we are doing anything, thinking, doubting, hoping, the fact is we are. We exist. What I did think was interesting in his argument in the beginning was when he said that we must doubt something that even has a small chance of being untrue. He mentions that his senses sometimes deceive him, as in dreaming. While extreme, this concept is essential.
On a slight tangent, with modern day technology and research we can corroborate this, but even in every day life. Elizabeth Loftus wrote in the 1980s about false memories.
This means that while we think we remember something, it did not in fact happen. So if our senses are really that unreliable where we think we have gone somewhere or done something that actually has never happened, then who is to say we aren’t brains in a vat being manipulated by bored scientists?
Descartes also mentions that there are some things that, whether dreaming or awake, are always true such as two plus three equals five and a square has four sides, a triangle has three, etc. However, if we truly are brains in a vat, isn’t it entirely possible that these truth elements could be altered? Couldn’t someone make us think that 2 + 2 = 5, just as we now think that 2 + 2 = 4?
Next, Descartes differentiates between the soul and the body. The body, he argues, is the structure of bodily parts (arms, hands, etc.) while the soul is where sense-perception and thinking occurs. While I don’t doubt that there must be some sort of location where thinking and perceiving occurs, I can doubt that I have a body. Again, we could just be brains in a vat where someone makes me think that I have a body that moves.
Thomas Hobbes responded to this separation of thought and body with, how can the body be separate from thinking as you need thinking to move the body? He says that “the mind is nothing more than the movements of various parts of an organic body.” These things Descartes describes as two separate entities, and yet, they cannot exist alone without ceasing in existence. This brings up for me a question of what it means to exist or be alive, but seems to be a totally different problem. Are we really living if we are brains in a vat? Aren’t we just a sort of zombie if someone is telling us what to think?
Moore wrestles with similar issues of what we can actually be certain. He says that there is no way to know for certain that he is not dreaming when he thinks that he, for example, is standing up. But he then argues that the sensory memories of the recent past “may be sufficient to enable [him] that [he] is not dreaming.”
He goes further to say that it is logical to argue that he may be dreaming right now and that he is dreaming would not be self-contradictory; but saying that he can’t be having both all sensory experiences and memories that he has, and be dreaming, is illogical and self-contradictory.
I believe that you could be dreaming and have sensory experiences and memory. Just as we can remember actual events, we can remember what has happened in a dream and sometimes the two blur. So couldn’t our memories of a “sensory experience” be just of a dream?
After reading this, I begin questioning whether I am actually a body and not a brain in a vat or living in a computer simulation, because as far as I can tell, there isn’t a way tell. Descartes and Moore reiterate one common conclusion for me: I am, but I also am certainly uncertain.
Hobbes: http://www.earlymoderntexts.com/pdfs/descartes1642_2.pdf