Descartes Essay, Research Paper

Descartes believed that we should ask what it would mean to know about reality,

and to examine what reality meant. He claims that unless we know first whether

our belief itself is justified we can’t know. To determine whether our beliefs

are justified, we have to be able to trace them back to a statement, belief, or

proposition that cannot be doubted. Like many other philosophers the only true

and believable facts are mathematical. But if achieved, such a proposition could

place the firm foundation on which all subsequent beliefs could be grounded; it

would guarantee that all subsequent claims based on it would be true. Descartes

was big on doubting everything. For us to distinguish this base of ultimate

truth and knowledge, of which all other knowledge can be based, Descartes

described a process. This method is to take away all confidence in which has

been taught, what the senses tell us, and what is thought is obvious, basically,

regarding all that is known by us. In order to determine whether there is

anything we can know with certainty, he says that we first have to doubt

everything. This doubting does not fully seem unreasonable. What he suggests is

that, in order to see if there is some belief that cannot be doubted, we should

temporarily believe that everything we know is questionable. Since sense

experience is sometimes deceiving, it is obvious to Descartes that there are two

operative ways of which to draw knowledge. They are intuition (A*B B*C) and

deduction (A*C). Anything else cannot be the basis for claims of knowledge. We

cannot know that what we experience through the senses is true with any

certainty. So the best thing to do is to doubt our senses. Furthermore, we

cannot be sure that we really exist, have bodies, or that experience of the

world in general can be trusted. After all, we could be dreaming the entire

thing. Next, we cannot even be sure that mathematical propositions such as 2+2=4

or that triangles always have three sides are true because some "arch

deceiver" as Descartes called it, might be deceiving us to think such a

thing. It is possible that even propositions that seem evident to us as true

might themselves be really false. But regardless if an arch deceiver deceives us

about all of our beliefs, there is one belief that we cannot be mistaken about.

And that is that we are thinking. Even doubting this is asserting it. Thinking

proves that we exist (at least as a mind or thinking thing, regardless of the

possesion of a body). The body is not an essential part of the self because we

can doubt its existence in a way that we cannot doubt the existence of the mind.

So Descartes concludes that I know one thing clearly and distinctly, namely,

that I exist because I think: "Cogito ergo sum," I think, therefore I

exist. From this starting point I can begin to note other truths that I know

clearly and distinctly, such as the principle of identity (A is A) and the

notion that things in the world are "substances." Since identity and

substance are ideas that are not based on sensation, they must be innate (that

is, they must be implicit in the very act of thinking itself). Even sensible

things (e.g., a block of wax) are knowable not based on sense experience but

intellectually, insofar as we know them to be the same things even though their

sensible appearances might change dramatically. In order to be certain that we

are not deceived when we claim to know something, Descartes must dispose of the

evil genie. This is done by proving that an all-good, all-powerful God would not

permit us to be deceived. If there is such a God, we can have knowledge. Since

the senses cannot be trusted to provide a proof that God exists, only a proof

based on the principle of the cogito ("I think, therefore I am") will

work. That proof can be summarized in the following way: I know I exist; but the

"I" who exists is obviously imperfect; otherwise I would not have

doubts about what I know in the first place. To know that I, an imperfect thing,

exist means that I already know that a perfect thing must exist in terms of

which my own existence is meaningful. I know what it means to be imperfect only

if I already know what perfection is. But I do not know perfection in virtue of

myself; therefore there must be a perfect substance (God) who exists in terms of

which my own imperfect existence is intelligible. No perfect (all-good,

all-powerful) being would deceive us into thinking that we know something with

certainty when, in fact, we are mistaken about it. So if there is a God, then no

arch deceiver could exist who tricks us regarding clear and distinct knowledge

(such as mathematical reasoning). We have a "great inclination" to

believe that there are physical objects that are external to the mind. But since

only those objects known in terms of mathematical properties–not those imagined

by use of the senses–can be known clearly and distinctly, the only knowledge we

can have of such objects is in terms of mathematical, quantifiable physics. The

only real knowledge we can have, then, is of things understood as functions of

laws of physics. The objects we see are not the objects we know, because what we

know is intelligible only in terms of the clarity and precision of the formulae

of physics. Information provided by the senses cannot therefore be the basis of

knowledge.

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