Descartes and “the brain in a vat”
In Descartes’ “metaphysical meditations 2”, he said: “I am therefore, precisely speaking, only a thinking thing.” That’s the conclusion he drew after he presumed that all the knowledge he had once acquired through his senses were all unreliable. Only the fact that “I am thinking” is real and by that premise he could conclude that “I am or I exist”.
In Descartes’ reasoning, only thinking makes a man a man, because the realization of one’s thinking has no relationship with one’s sense. However, in 17th century, the bio-science had just begun to develop, and people’s knowledge of the human being is not only scarce, but full of mistakes. Even the most intelligent philosopher, like Descartes, wrote sentences like “...persons in a state of insanity, whose brains are so disordered and clouded by dark bilious vapors as to cause them pertinaciously to assert that...”. Nowadays we obviously know that there’s nothing like “dark bilious vapors” in our brain.
As the bioscience develops, we came to know that the reasoning in the brain actually works through electrical impulses. Thus another question rose: isn’t reasoning another kind of process of receiving senses from outside? And thus a famous experiment named “the brain in a vat” appeared.
The concept of this experiment could be depicted in an easy way: a brain was removed from a person’s body, and kept in a vat full of lifesustaining liquid, which guaranteed its function. Then the brain was given the identical electrical impulses it received in a human body, so how could it tell that itself was in a vat or in a body?
[picture from Wikipedia]
Many thinks that the concept of “the brain in a vat” stems from Descartes’ view of senses and also his skepticism. He thinks that there’s a “genius malignus” who tried to cheat him, making him believing in all the knowledge acquired via senses, while he actually even have no organs of senses. Similarly, the mad scientist who kept the brain in a vat could be viewed as the “genius malignus”.
If the only thing that Descartes considered reliable, which is thinking, became the same as the other senses we have, and therefore became unreliable, what can we really trust? Then maybe the only way we could go is the full skepticism.
[to be continued]
I like your post Chengzhi, I think it is interesting when you incorporate the thoughts of Descartes to modern findings. I think, independent that thinking come also of the senses, it cannot be denied that we are thinking all the time. How can man be sure that absolutely nothing is certain if man doesn´t think? Maybe it is a contradiction in Descarte´s thoughts.
ReplyDeleteWhen I read your comment, another idea came to my mind related with the issue that "only thinking makes a man a man". There are a lot of people that cannot think because they are in coma, but they are still alive, then they exist. However, according to Descarte´s reasoning, these people wouldn´t exist since they cannot think. For me, this is another example of contradictions in his ideas.
Thx for the comments, as the example of people in coma that you mentioned, I think the concept of "exist" to Descartes was not a scientific one but a philosophical one, but at that time philosophers tended to mix them up, partly due to the underdevelopment of science. Anyway, we cannot deny the existence of people suffering from Alzheimer's disease or other mental problems.
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