JCCMI- Phil Week 5 Dis 1
Lecture Attached
Post (1) a summary of an argument found in Cartesian Doubt and the Search for Foundational Knowledge and (2) a critique of that same argument. Follow the usual guidelines for your argument summary (using the premise-conclusion form) and follow the guidelines given previously for writing your critique.
Week 5: Cartesian Doubt and the Search for Foundational Knowledge
We begin our study of epistemology with Rene Descartes Meditations. Descartes tells us he wants to rid himself of his false opinions and to begin again from the first foundations. Notice how Descartes uses the metaphor of a building or a structure. He thinks of knowledge as having foundations and other knowledge built upon the foundations. Pause a minute here and think about what that might mean. Why would some knowledge be more foundationalwhat is it about that knowledge that makes it foundational? When some knowledge is built upon some other knowledge, does the former depend on the latterwhat does dependence mean here? Are there better and worse ways to build an edifice of knowledge?
Descartes thinks foundational knowledge should be certain, and he thinks that the foundational knowledge serves as justification for the rest of what one knows. From this, we can infer that the best-built structures of knowledge are those in which (i) the foundations are completely certain and (ii) the non-foundational knowledge follows from the foundational knowledge deductively. If that is how ones edifice of knowledge is erected, then one wont have any false beliefs. Ones structure of knowledge will reflect the truth. Descartes wants to have this sort of knowledge, so hes trying to find beliefs of which hes absolutely certain to use for his foundation. In order to find the absolutely certain beliefs, he decides to doubt everything he can. His idea is that if theres a belief he cant possibly doubt, then he can be certain of that belief.
Rather than go through his beliefs one-by-one trying to doubt them, Descartes all at once throws into doubt all the beliefs hes come to have on the basis of sensory experience. He supposes that most of what hes come to believe has come from his senses, but he wonders if his senses are a reliable guide to truth. If his senses have ever misled him, then they cant be fully trusted as a source of knowledge. And, of course, Descartes senses have misled him. We get unreliable information from our senses all the time. If you look at pavement on a hot day, it looks like its wet, but its not. If you look at a stick thats half-submerged in water, itll look like disjointed or bent at an odd angle (depending on the angle from which youre looking). These are cases in which what you see is inaccurate, cases in which it looks like your perceptual capacities dont lead you to truth. So Descartes can doubt the beliefs hes come to have by virtue of perceptual experience; hence, he wont use any of these beliefs in his foundations.
But he doesnt stop there. Descartes considers the possibility that hes dreaming. Have you ever dreamt something and believed at the time that it was real? I had a dream not long ago that I was sitting beside a lake, when I woke up, it took a minute for me to realize that I hadnt really just been sitting beside a lake. When youre having a dream like that, you dont know at the time youre dreaming it that its just a dream. If someone were to ask you in the dream whether youre dreaming, youd say you arent. You think youre beside a lake (or wherever)not in bed, dreaming. But youre wrong. Because in those cases, you are in your bed dreaming. Descartes wonders if he can be absolutely sure at any moment that hes not having a dream like that. Are you absolutely sure that you wont wake up in a moment and realize youd been dreaming about reading a lecture for your philosophy class? Keep in mind that if you were having such a dream, youd be absolutely convinced that youre not dreamingjust like you probably are now, so your conviction that youre not dreaming isnt enough to prove that youre not really dreaming. You could be. And, if you could be dreaming, then youre not absolutely sure that youre not dreaming. And if youre not absolutely sure that youre not in your bed dreaming, then theres a whole lot more that youre not sure of either: youre not sure that youre looking at a computer screen; youre not sure which day of the week it is; youre not sure how old you are. If you have to be sure of something to know it, then you dont know where you are or when.
But thats not all! The thing is, when youre having one of those dreams, you dont really know anything about what the non-dream world is like. You might wake up and be a completely different person than who you think you are in your dreamyou might be a different gender, a different race, a different age; you might live 2000 years after the time it seems it is in the dream or 2000 light years away. You might wake up to discover that youre a slug living on Mars. If you dont know whether youre dreaming or not, it could be that having a body at all is part of the dream, when in reality, youre just a disembodied soul. It may be that Earth is just part of your dream, and there isnt really any material universe at all. If you cant be sure of any of it, you dont know any of it.
So then maybe you dont know anything. Theres nothing you know for certain, so theres nothing you can use in the foundation for you edifice of knowledge. You dont even know that you dont know whether youre really so ignorantits just possible that you are, but its also possible that youre just dreaming that you dont know anything.
After thus destroying the edifice of knowledge, Descartes rebuilds. He finds something that he thinks is completely indubitablesomething that he just cannot doubt. Its his own existence. Its not that he cant doubt it because hes constitutionally unable to or because it would be too painful for him. Its that he cant doubt it without contradicting himself. Recall that he started out by asking what he could doubt. For any belief he came across, he asked whether he could doubt it; if he could, he decided that he must not know it for sure. Can he doubt that he exists? He thinks he cant.
Why not? Notice that if he doubts that he exists, then he has reason to believe that theres something doing the doubtingthat is, when he doubts, he does something. And in order to do something, one must exist, of course. So hes got to exist in order to doubt his existence; but if he exists in order to doubt his existence, it must be a contradiction to doubt his existence. So he cant doubt that he exists without contradiction. So he knows that he exists; hes certain of it.
In fact, he thinks he knows more than that. Suppose he tries to doubt that hes doubting. But in order to try that, hes got to doubt; and, if he doubts, hes doubting. So, again, he cant doubt that hes doubting without contradiction. Moreover, since doubting is a kind (or species or mode) of thinking, and Descartes cant doubt that hes doubting, he knows, hes certain, that hes thinking.
Descartes uses these ideas to resurrect the edifice of knowledge hed previously torn down. In our reading, he reasons that he must be a thinking thing and not a body, since he can conceive of existing without a body but not without a mind. That is, he would contradict himself if he were to think that he exists but isnt thinking, but he wouldnt do so if he were to think that he exists but has no body. So he concludes that he is, essentially, a thinking thing. A thing that doubts, understands, affirms, denies, wills, refuses, and which also imagines and knows. (194)
When you read the excerpt from John Locke, ask yourself how Descartes might respond.
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