Reading: Cartesian Epistemolgy

Rene Descartes has had a very strong influence on philosophy since his life. One of his important areas of writing have to do with his theory of knowledge or epistemology. The following excerpt from the Stanford Philosophical Library will give us a glimpse of the central thought of Descartes on what we know. -RZ

Rene Descartes’ Philosophy of Knowledge

René Descartes (1596–1650) is widely regarded as the father of modern philosophy. His noteworthy contributions extend to mathematics and physics. This entry focuses on his philosophical contributions in the theory of knowledge. Specifically, the focus is on the epistemological project of Descartes' famous work, Meditations on First Philosophy. Upon its completion, the work was circulated to other philosophers for their comments and criticisms. Descartes responded with detailed replies that provide a rich source of further information about the original work. He indeed published the first edition (1641) of the Meditations together with six sets of objections and replies, adding a seventh set with the second edition (1642).

Famously, Descartes defines knowledge in terms of doubt. While distinguishing rigorous knowledge (scientia) and lesser grades of conviction (persuasio), Descartes writes:

I distinguish the two as follows: there is conviction when there remains some reason which might lead us to doubt, but knowledge is conviction based on a reason so strong that it can never be shaken by any stronger reason. (1640 letter to Regius, AT 3:65)

In the preceding few sentences, Descartes is saying that there are times when we have to distinguish between what we can confidently assert as a conviction and what we cannot so confidently affirm to be convinced of. The first he calls knowledge and the second is not knowledge as far as he is concerned.  It has to do with how shaky our convictions are. If we know something so profoundly that it cannot be shaken by any doubts or reasons put forth in an argument, then it is knowledge. – RZ

Elsewhere, while answering a challenge as to whether he succeeds in founding such knowledge, Descartes writes:

But since I see that you are still stuck fast in the doubts which I put forward in the First Meditation, and which I thought I had very carefully removed in the succeeding Meditations, I shall now expound for a second time the basis on which it seems to me that all human certainty can be founded.

First of all, as soon as we think that we correctly perceive something, we are spontaneously convinced that it is true. Now if this conviction is so firm that it is impossible for us ever to have any reason for doubting what we are convinced of, then there are no further questions for us to ask: we have everything that we could reasonably want. … For the supposition which we are making here is of a conviction so firm that it is quite incapable of being destroyed; and such a conviction is clearly the same as the most perfect certainty. (Replies 2, AT 7:144–45)

As we will be seeing in the material that follows, Descartes sees knowledge as the opposite of doubt. Ignorance is not doubt, and it is not the opposite of knowledge. It is doubt which raises the uncertainty in one’s heart concerning the truthfulness of a particular assertion, it is not ignorance that does so.  Here is a for example,: If I  say, “I know beyond a shadow of a doubt, that my guilt has been paid for by the suffering and death of Jesus,” then that is knowledge that I have. Now if Satan wants to challenge that in my life, he will not attack it head on and tell me I am ignorant. Instead, the Serpent will ask, “Is it really so? Did God really say? …” In doing so, he casts doubt into or hearts and destroys our knowledge. -RZ

These passages (and others) clarify that Descartes understands doubt as the contrast of certainty. As my certainty increases, my doubt decreases; conversely, as my doubt increases, my certainty decreases. The requirement that knowledge is to be based in complete, or perfect certainty, amounts to requiring a complete absence of doubt — an indubitability, or inability to undermine one's conviction. Descartes' methodic emphasis on doubt, rather than on certainty, marks an epistemological innovation. This so-called ‘method of doubt’ is discussed below (Section 2).

The certainty/indubitability of interest to Descartes is psychological in character, though not merely psychological — not simply an inexplicable feeling. It has also a distinctively epistemic character, involving a kind of rational insight. During moments of certainty, it is as if my perception is guided by “a great light in the intellect” (Med. 4, AT 7:59). This rational illumination empowers me to “see utterly clearly with my mind's eye”; my feelings of certainty are grounded — indeed, “I see a manifest contradiction” in denying the proposition of which I'm convinced. (Med. 3, AT 7:36)

In the denomination I grew up in, when a person was going to be baptized, the pastor would read a set formulary for baptism. In that formulary it would be said that baptism is an “indubitable sign and seal” of the promises of Most High God. I find that language to be instructive as I read Descartes’ affirmation of what is true. It has the character of being “indubitable.” -RZ

Should we regard Descartes' account as a version of the justified true belief analysis of knowledge tracing back to Plato? The above texts (block quoted) are among Descartes' clearest statements concerning the brand of knowledge he seeks. Yet they raise questions about the extent to which his account is continuous with other analyses of knowledge. First of all, his characterizations imply a justified belief analysis of knowledge — or in language closer to his own (and where justification is construed in terms of unshakability), an unshakable conviction analysis. There's no stated requirement that the would-be knower's conviction is to be true, as opposed to being unshakably certain. Is truth, therefore, not a requirement of Descartes' brand of strict knowledge?

Many will balk at the suggestion. For in numerous texts Descartes writes about truth, even characterizing a “rule for establishing the truth” (Med. 5, AT 7:70, passim). It might therefore seem clear, whatever else is the case, that Descartes conceives of knowledge as advancing truth. Without denying this, let me play devil's advocate. It is not inconsistent to hold that we're pursuing the truth, even succeeding in establishing the truth, and yet to construe the conditions of success wholly in terms of the certainty of our conviction — i.e., wholly in terms of internalist criteria. Thus construed, to establish a proposition just is to perceive it with certainty; the result of having established it — i.e., what gets established — is the proposition's truth. Truth is a consequence of knowledge, rather than its precondition. Note again that Descartes says, of the perfect certainty he seeks, that it provides “everything that we could reasonably want,” adding (in the same passage):

What is it to us that someone may make out that the perception whose truth we are so firmly convinced of may appear false to God or an angel, so that it is, absolutely speaking, false? Why should this alleged “absolute falsity” bother us, since we neither believe in it nor have even the smallest suspicion of it? (Replies 2, AT 7:144–45)

On one reading of this remark, Descartes is explicitly embracing the consequence of having defined knowledge wholly in terms of unshakable conviction: he's conceding that achieving the brand of knowledge he seeks is compatible with being — “absolutely speaking” — in error. If this is the correct reading, the interesting upshot is that Descartes' ultimate aspiration is not absolute truth, but absolute certainty.

On a quite different reading of this passage, Descartes is clarifying that the analysis of knowledge is neutral not about truth, but about absolute truth: he's conveying that the truth condition requisite to knowledge involves truth as coherence. Harry Frankfurt defended such an interpretation in his influential 1970 work, Demons, Dreamers, and Madmen. Yet, in a follow-up paper he retracted the view:

I now think, however, that it was a mistake on my part to suggest that Descartes entertained a coherence conception of truth. The fact is that there is no textual evidence to support that suggestion; on the contrary, whenever Descartes gives an explicit account of truth he explains it unequivocally as correspondence with reality. (1978, 36f)

More recently, Ernest Sosa (1997a) and Michael Della Rocca (2011) have helped revive interest in whether Descartes should be read as holding some form of coherence theory.

A definitive interpretation of these issues has yet to gain general acceptance in the literature. What is clear is that the brand of knowledge Descartes seeks requires, at least, unshakably certain conviction. Arguably, this preoccupation with having the right kind of certainty — including its being available to introspection — is linked with his commitment to an internalist conception of knowledge.

In characterizing knowledge as “incapable of being destroyed,” Descartes portrays knowledge as enduring. Our conviction must be, he writes, “so strong that it can never be shaken”; “so firm that it is impossible for us ever to have any reason for doubting.” Descartes wants a brand of certainty/indubitability that is of the highest rank, both in terms of degree and durability. He wants knowledge that is utterly indefeasible. (Sceptical doubts count as defeaters.)

This indefeasibility requirement implies more than mere stability. A would-be knower could achieve stability simply by never reflecting on reasons for doubt. But this would result in mere undoubtedness, not indubitability. Referring to such a person, Descartes points out that although a reason for “doubt may not occur to him, it can still crop up if someone else raises the point or if he looks into the matter himself” (Replies 2, AT 7:141).

Retrieved from http://plato.stanford.edu/entries/descartes-epistemology/