René Descartes (1596–1650)

This must-read classic of modern philosophy lays out, in great detail, the primary skeptical challenge that philosophers are still trying to dig out of today. While the phrase “I think, therefore I am” is an important philosophical find (denying your own existence presupposes your existence), the deeper issue Descartes uncovered is that, beyond the certain knowledge of your own existence, you could still be wrong about everything else.

Descartes sought to reject any of his beliefs that show more introduced even the slightest degree of doubt. He began by finding reason to distrust the senses, along with his ability to distinguish dreams from waking life. He then imagined the possibility of being deceived by a “malicious, powerful, cunning demon” that convinced him of seemingly certain—albeit false—beliefs, such as the mathematical truth that 2 3=5.

The result was that Descartes had to reject all of his beliefs, as they were all subject to some degree of doubt. But there was one belief that was beyond doubt: the certainty of his own existence, which even the evil demon could not call into question. (It’s possible to think false beliefs, but it’s not possible to think you’re thinking when you’re not.)

Modern versions of “Descartes’ demon” include the possibility that we are all living inside a computer simulation or that we are “brains in a vat” manipulated by scientists to simulate artificial experiences. The unnerving thing about these scenarios—for those who have given them sufficient consideration—is that, despite their apparent implausibility, there is no way to disprove them. I may be certain of my own existence, but the nature of this existence is still left wide open. I could exist in a computer simulation, as a brain in a vat, or as an immaterial entity manipulated by an evil demon. How could I prove otherwise?

So how do you deal with this skeptical challenge? I see three main options: (1) deny the possibility of any knowledge at all, following the ancient Pyhronnian Skeptics, (2) ground knowledge in the idea that God is a perfect being and wouldn’t deceive you, as Descartes did, or (3) accept that certain knowledge is not possible but that certainty is not required for knowledge (the critical rationalist approach). I suppose the fourth possibility is to remain blissfully unaware of the problem at all.

Descartes pursued the second option, using a version of St. Anselm’s ontological argument to demonstrate that God is perfect and would never deceive him. This is ultimately a failed solution, as the ontological argument has so many valid objections and refutations that today it is not taken very seriously even by theists.

Further, Descartes ultimately argues in a circle to get out of his own dilemma. He tells us we shouldn’t trust our judgment regarding the basic truths of arithmetic, such as 2 3=5, but then tells us we should trust our judgment regarding the existence of a perfect being that wouldn’t deceive us. But since he tells us that we shouldn’t trust our judgments before establishing the existence of God, how can we then trust our judgments concerning the existence of God?

So Descartes introduced a critical philosophical problem but blatantly failed to resolve it. This is why I see his legacy as mixed. I also see Descartes as getting too much credit in two important respects.

First, Descartes is often referred to as the “father of modern philosophy,” yet Francis Bacon published his masterwork, the Novum Organum, in 1620, a full two decades before Descartes published the Meditations in 1641. Bacon laid out a new system of philosophy that influenced both the founding of the British Royal Society and later the Encyclopédie of the Enlightenment. Bacon’s attack on Aristotelianism and Scholasticism and his charting of a new path for philosophy and science based on inductive reasoning suggests to me that he is the real father of modern philosophy, not Descartes.

Second, Descartes is not the first philosopher to engage in a process of systematic doubt or to develop arguments against the reliability of the senses. The ancient Phyronnian skeptics, as well as Sextus Empiricus, hold that distinction, and would not have viewed his distrust of the senses as particularly innovative.

My recommendation would be to read the Meditations for Descartes’ systematic method of doubt, an understanding of the skeptical challenge, and the reasoning behind the certainty of your own existence. Beyond that, ignore his solutions and instead read the works of Karl Popper to see how critical rationalism is the only workable, albeit imperfect, solution to the skeptical challenge. show less

This is not an easy collection of writings to review. How does one sum up writing that attempts to lay out a method for and then drive to what becomes a core principle of rationalist approaches to modern philosophy? Descartes offers his own summary in cogito ergo sum -- I think, therefore I am. And the fact that you have mostly likely heard this phrase and can link it to Descartes suggests the influence this work has had.

I'll be the first to admit that although I had certainly heard the show more phrase "cogito ergo sum" and probably had to read some of Discourse on Method at some point in my undergraduate years, I had next to no concept of why the observation was so meaningful. So here is an attempt to put it in perspective that made sense to me (upon a couple of readings).

Imagine anything that you know or take to be true and divide/dissect it into the core claims, assumptions, beliefs, and measurements that comprise it. How many of those component pieces of the thing that you hold true are things that you, personally, know distinctly and with certainty? Now take all those core claims, assumptions, beliefs, and measurements from the first dissection and divide/dissect those into the claims, etc. that they are built on. If you are engaging in this process honestly, then you now have exponentially more claims, etc. And ask yourself: of all those claims, etc., how many do you, personally, know with certainty or distinctness? Now imagine, after layers of mental dissection, you have the idea that you took as truth disassembled into hundreds of component claims, etc., all stacked on each other in strata. Imagine that some of those claims etc. can be doubted and a contrary position stated. Maybe it's a handful of such claims, etc. that can be doubted, but how many before the initial truth unravels? Truths that we adopt because they are given to us are built upon similar structures of claims, etc., so how can you really know that any of those things are true?

Descartes offers a method for engaging in this kind of work as well as a starting truth: cogito ergo sum. It is the base truth that cannot be doubted. You are having thoughts all the time. And if you are having thoughts, you exist. And if you are not, then you don't. Truth builds upon this core truth, iteratively and (if we do it right) carefully. All of the faculties of reason that are in us can be confidently used in the pursuit of truth by exposing doubts and reasoning our way through them to indubitable claims from which we can make reasonable inferences and deductions. Except with the senses ... they're a little too unreliable.

Now I'm a bit less skeptical of empiricism than Descartes, but I understand where he was coming from about the potential fallibility of the senses. As I see it, sense data, aided by reason, disciplined by a method of analysis (e.g., the scientific method) can yield the "clear and distinct" impressions that Descartes says are important to truth. In fact, empiricism seems to give a better definition of what clarity and distinctiveness might mean -- more so than is easily extracted from this volume.

At times a bit too insistent on the importance of God to establish the perfection that becomes the goal of doubting and dismissing doubt. Descartes acknowledges the ancients but then also dismisses them; yet, there seems to be more in this volume that is owed to Plato and Aristotle than is acknowledged.

Nevertheless I have to give this foundational work at least 4-stars. Any less is just iconoclastic. show less

In the Discourse Descartes is charming, down-to-earth, and his investigation of skepticism is exciting, fun and profound at the same time. That’s a rare combination in philosophy, at least in my experience - only Plato and Chuang Tzu come to mind as similar in this respect (maybe Nietzsche, but he’s such a ninny). Although Descartes’ skepticism is arguably a borrowing from ancient philosophy, his turning it into a method of investigation appears to be original, and it was enormously show more important in the development of modern science as well as modern philosophy.

I think his famous cogito ergo sum (I think, therefore I am) is flawed – perception of thought proves the existence of operating consciousness, but not the existence of an individual, thinking being. Hair-splitting and navel-gazing to some, a big deal to others. But all good, clean fun. The Meditations, on the other hand, is not so charming, it’s often boring, and it’s sometimes profound and sometimes not very. It has a couple weak and fallacious arguments for the existence of God - you get the impression that, after the relentless skepticism of his Discourse and the first couple meditations, and in light of Galileo’s travails, he’s trying to keep himself in the good graces of the Church and neither his heart or head are completely in the proofs of God and the things leading up to them. At least that’s the impression I get. If I exist.

But I’m a bit hard on Rene, and he lived in hard times. The Discourse, written in French, was aimed at a more popular audience while the Meditations, written in Latin, was for scholars. And it is more substantial. Speaking of Chuang Tzu, Descartes could have lifted his dreaming argument from the old sage, but it’s highly unlikely he’d ever heard of him (and his recollection-like a priori knowledge of mathematical objects is straight out of Plato’s Meno). This dreaming together with the evil god concept puts us in pretty shaky epistemological territory. The search for anything knowable is a logical next step, but beyond that Descartes tends to build his house with quite a few cards. Still, it’s probably not unreasonable to say that what he accomplished was revolutionary, and that it engendered a remarkable quantity and quality of further developments for hundreds of years. To be fair, Descartes’ mind-body dualism is pretty much from Plato as well; apparently he wasn’t big on attribution, but so it goes. show less

These are undeniably important works. The introduction calls Descartes the "originator of modern philosophy." This is also very lucidly written--I think the arguments are perfectly accessible to the layman, it's just I don't think much of them. The full title of the first treatise of only 54 pages is "Discourse on the Method of Rightly Conducting One's Reason and of Seeking Truth in the Sciences" but would more correctly be titled, "A Rehash of Just about the Lamest Philosophical Proof of show more God Ever." The first three sections of the six section treatise sound pretty commonsensical for the most part, the core of the "method" seems to be detailed in Part II:

The first was never to accept anything for true which I did not clearly know to be such; that is to say, carefully to avoid precipitancy and prejudice, and to comprise nothing more in my judgment than what was presented to my mind so clearly and distinctly as to exclude all ground of doubt. The second, to divide each of the difficulties under examination into as many parts as possible, and as might be necessary for its adequate solution. The third, to conduct my thoughts in such order that, by commencing with objects the simplest and easiest to know, I might ascend by little and little, and, as it were, step by step, to the knowledge of the more complex; assigning in thought a certain order even to those objects which in their own nature do not stand in a relation of antecedence and sequence. And the last, in every case to make enumerations so complete, and reviews so general, that I might be assured that nothing was omitted.

It would be nice if Descartes then gave an example of how by such principles he solved a scientific problem, but no. He then proceeds in Part IV to decide that the first principle from which all else is to be deduced is the famous dictum, "I think, therefore I am." Except I'd stop right there and challenge that as a first principle. We think based on our experiences of the world as meditated by the senses. Read Helen Keller's autobiography some time for some appreciation of how impossible it is to think without language, and to get language without association between a discrete experience and means of communication. But that's not all, from that first principle Descartes proceeds to leap to the the conclusion that there must be a God. Why? Because since he has doubts in this thinking he's not perfect, but something must be, and nothing is perfect but God. That is the ontological argument for God, which is not original to Descartes but is attributed to the 11th Century Anselm of Canterbury. Descartes even claims this "proof" is more solid than the experience of our own bodies, and from this deduces the idea of the mind/body dichotomy. The six Meditations are basically an elaboration on this theme.

So why am I even rating it as high as three stars? This isn't a philosophy I can and wish to ascribe to, but yes, given its importance I do recommend reading it--it's not long either, the book containing both treatises is only 143 pages. Descartes treatises were tremendously influential in provoking disparate philosophers from Spinoza to Berkeley to Hobbes to form their own views as they sought to refine or refute Descartes arguments. show less