Cartesian Skepticism

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This is the the second post in my Theories of Knowledge and Reality series. Follow the link for the introduction to the series that explains what it's all about and the list of posts in the series, which I will update as they appear.

Perhaps the most famous line in the history of philosophy is Descartes' "I think therefore I am". What's often misunderstood is what he meant and why he was saying it. He wasn't saying that only things that think exist, as if thinking is what makes us exist, though many jokes rely on that mistake. [Descartes walks into a bar. The bartender asks him if he wants a drink. He says, "I think not" and promptly disappears.] What Descartes was up to with that line, often called the Cogito (from the Latin "cogito ergo sum"), was a response to a particular skeptical claim, and it was the beginning of an extended response to skepticism that most philosophers today believe was completely ineffective. They do, however, tend to think that the skeptical questions he raised are very difficult to get around, and they attribute the persistence of skepticism to him, even if his goal was to refute it. This is how these things go sometimes.

What I want to do in this post is motivate the kind of skepticism Descartes raised. I'll proceed to other kinds of skepticism and responses to skepticism in further posts.

The ancient skeptics had argued that we shouldn't believe anything. Most of their examples had to do with trusting our senses or philosophical views. They said that any view can have a counterargument, so we shouldn't believe anything, and they argued that any perception can have a contrary one from another person, from the same person at a different time or with a different sense, or from how animals perceive from how we do. We have perceptions, and you don't deny your perceptions, but you don't affirm them either.

The Cartesian skeptic is more radical in one sense, however. Descartes, when he starts off his Meditations by portraying the doubts of the skeptical frame of mind, raises doubts not just about particular things, with the particular arguments the ancients had used. He gives these comprehensive skeptical scenarios, which if true would mean most of our beliefs are false. If everything I perceive right now is just a dream, then I don't know if any of it is real. If it could have been presented to me by an evil deceiving spirit, then I don't know if any of it is real. The contemporary example is the Matrix. If I don't know that I'm not in the Matrix, then how do I know there's really a computer here that I'm typing on. How do I even know I have hands? Everything that seems to be true could simply be a delusion created by a mad scientist or evil demon.

The structure of the argument is extremely important, because the responses to the argument have to pay attention to the details of what's being said and what's concluded on what basis. The crucial issue here is that, if X implies Y, then our inability to know Y means we cannot know X.

If we can't know that we're not in the Matrix or dreaming, or deceived by a neuroscientists, then we can't know that our beliefs about our own hands are about real hands we have. Yet it seems obvious that we can't know that we're not in the Matrix. The Matrix scenario is just as consistent with my evidence as the more common belief of what's going on around us -- that there really are these objects out there in the world, and I'm perceiving them. In both cases things seem as they seem. So how can I know which one is true? But then if I can't know I'm not in the Matrix, then I can't know what wouldn't be true unless I weren't in the Matrix -- that the hands I seem to be seeing and feeling are really there.

This works with any ordinary belief that wouldn't be true if some skeptical scenario that you can't absolutely rule out were true. If the skeptical scenario that you can't rule out would have some belief of yours turn out false, then you don't know that thing that you believe. This is why Descartes' skeptical arguments lead to a truly radical conclusion. We know hardly anything. In the next post, I'll sketch out how similar arguments can lead to some serious skepticism even without radical skeptical scenarios, and then I'll examine various responses to skepticism.

Update: If you want to read Descartes for yourself, I suggest using Jonathan Bennett's translations of the Meditations. It's designed for people who aren't familiar with reading early modern philosophical texts. Those who are familiar with this sort of thing should of course look at one of the most recent scholarly translations (not that Bennett isn't a scholar, but these texts were prepared for introductory courses), but those just exploring this sort of thing for the first time can probably benefit most from Bennett's version, which is more readable than any other translation you could possibly find and sometimes contains some commentary set off in brackets. For more information on what sorts of things he's done in his translations, see this page. If you want a more traditional translation, Bennett recommends Cottingham. If you want one online, see here.


Is this in any way related to solipsism, or am I thinking apples and oranges here? Is there a connection between skepticism, i.e., are they different points on a continuum, or am I merely showing my ignorance?

Be gentle, please.



One more thing: what books would you recommend I read as I try to follow this series? I think I have Geisler's around somewhere, as well as Moreland & Craig's text. Would either help? Are there others?

Thanks again.

Solipsism is the view that the person holding the view exists and no one else does. Skepticism about some purported body of knowledge is the view that I don't have knowledge about that thing. A skeptic about the existence of God doesn't think we know anything about God, if God even exists, though they might continue believing in God nonetheless and just not call it knowledge. An atheist denies that there is any such being. When it comes to the existence of other people, a solipsist is analogous to atheism, whereas a skeptic about the existence of other people simply doesn't think they know that other people exist. They may still believe in them. A solipsist doesn't even believe in the existence of other people.

Strange as it may sound, one of the best introductory level presentations of this stuff is in Thomas Morris' Philosophy for Dummies. I use so many different sources that I can't just point you to a textbook that I use. When I get to stuff that more heavily relies on material I do use, I'll indicate what that is. This does remind me to put a link to Descartes in the post, though.

Jeremy - you seem to have left out how "I think therefore I am" was an attempt to refute readical skepticism. So I'll do my best to fill in that gap (feel free to correct me).

Descartes reasoning went something like this:
1) I may be living in the Matrix.
2) If I live in the Matrix, I can't be sure of any sensory input. In fact, I can't be sure anything exists. I.e. I doubt all knowledge.
3) However, I know that I doubt.
4) Therefore, I must exist, for if I didn't exist, then I couldn't doubt.

And since doubting was a form of thinking, Descartes summed up his refutation of radical skepticism as "I think therefore I am."

Mike - another good intro to philosophy is "Looking at Philosophy: The Unbearable Heaviness of Philosophy Made Lighter" by Donald Palmer. (Warning, all of the text is written in Comic Sans, so if you don't like that font, this book is not for you.) Palmer gives 5-15 pages of very readable summary of almost every major figure in philosophy. Of course, he has to simplify things a lot to do so, but that is the nature of intro survey books. That being said, he does a very good job if it (IMHO).

Hey, no jumping the gun! I said, "In the next post, I'll sketch out how similar arguments can lead to some serious skepticism even without radical skeptical scenarios, and then I'll examine various responses to skepticism." That argument's still two posts away.

lol! I'm saving my surprisingly dumb questions for later on. :)

Ha Ha ... Do you know any other Decartes jokes ?

There's one about getting Descartes before the horse, but I don't remember how it goes.

Ooops...sorry. It's just that you brought up "I think therefore I am", and then didn't mention it again. I didn't realize you were waiting for post 3.

Would Solipsism be a form of extreme narcissism?

I wouldn't think so. You can think you're the only intelligent mind in existence without loving yourself very much. It's not about how much you like yourself. It's about coming to the conclusion that other people, whether you like them or not, don't really exist.

It would seem that Solipsism would be the ultimate form of narcissism.

I disagree that the solipsist view is necessarily narcissistic. It is possible that the person believing that they are the only one would rather that they did not believe that but due to the amount of proof they feel they need to know that any other consciousness exists, which they do not feel they have, they are unable to believe that anyone does exist but them.

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