Two Mistakes and Scepticism

He doesn’t doubt everything; but doubts the sources used in the acquisition of knowledge. As I’ve posted before:

“You must examine all human knowledge and see if it can be doubted. If it is dubitable and so ‘infected’, then it must be mercilessly rejected as flawed. I asked myself where all human knowledge comes from. I decided there are only two sources of knowledge: our sense and our reason.”

This is where he starts his sceptic journey. It just so happens none of these source can be found to be indubitable, so for a sceptic all is doubtable until he realises that he must have a consciousness to observe his own doubting, this he can’t doubt.

This isn’t exactly what Descartes says or does. An example: Imagine a river flowing down the side of a mountain and on it’s journey it passes through 4 villages. The 1st is closest to the rivers source, and the 4th closest to the sea. Now if the first 3 villages use this river to bath in, by the time it gets to the 4th the water could be quite dirty. The first village gets clean water, the second is slightly dirty, the third is more dirty, and then finally the fourth the waters dirty. If the 4th village wants clean water it must get it between the source and before the first village, because beyond that point it becomes contaminated. Now if somebody wanted to poison everybody in all of the 4 villages all they would need to do is go to the river’s source and mix in the poison there. The flow of the river would then automatically poison everybody and everything a long it’s path.

This is the same for the two sources of knowledge that Descartes believes all knowledge stems from. If the source itself is contaminated with doubt, this doubt will be passed onto all knowledge that springs from it. I hopefully explain this clearly in my post about “questioning opinions”

The part in bold is not true, yes he accepts that he has senses, but not that they are true or that they are real, only that it appears he has them. The only certainty is that he is thinking about this problem, but for everything else, there is no certainty, as when he sleeps these senses give him very different pictures of the world, which we call dreams. How do we know we’re not in some dream like state right now? Most people have at one time in their life woken up in a cold sweat from a nightmare that they believed to be true, up until the point of waking that is. How do I know I’m not going to wake up before I finish reading this post?

Even the most simplistic of animal brains have the ability to doubt. I would also speculate that doubt would be one of the first “conscious” brain functions acquired. Why? Because of the ‘Fight or Flight’ response. To make the decision to Flight or run away is to doubt that you can Fight and win. All animals have this ability; all animals are capable of doubt even if they don’t have beliefs or a historical context. It’s much more basic then that. Yes he’s right they do shape them, but that view is more of an anthropologists view then a philosophical one.

I have cover indirectly in my other reply to you on “questioning opinions”. If you would like a fuller account let me know and I’d be more the happy to type it up.

Definitely got some good stuff here and in the other thread. Let me try to address three points here:

First,

Now, I’ve taken the Davidsonian route here, but you can also take the Wittgensteinian route and question the connection between dubtibility and knowledge. I’ll let that go for now, but I want to point out that this quote already presupposes his conclusion. Why did he decide that there are only two sources of knowledge? Why lump all five sense together and call it sense, why separate this from thinking processes? Why, in fact, call these sources, even separate sources, of human knowledge and not facets of a holistic human individual? Senses and reason aren’t sources of knowledge, they are what make us us. Do you see how the conclusion is foretold by the premises inherent in this quote?

It may seem like I’m being a little hard on the old French guy here, but that’s not really my intention. I think these basic Cartesian intuitions are still the default position for many, and while I probably won’t be able to persuade many people that there’s a better way to go, I might be able to modify this dualism just a bit and, as I said before, show that we aren’t cut off from the world at all. Of course, I suppose I haven’t done a very good job at doing that yet.

I’ll address your river source point later, but I see no inherent reason to confine ourselves to two abstract sources of knowledge and many good reasons to see many ways of checking and double checking what you call sources. To go back to the stick for example, how does Descartes know that his senses are deceiving him if he didn’t, I don’t know, thrust his hand in the water and find his sight misleading him. It seems very clear to me at any rate that he just could have accepted that something about the distinction between water and air changes the nature of the stick rather than the nature of his sight. Now, you’ll probably say that he doesn’t know that he’s being deceived, he’s only stating the possibility of being deceived – two different things – but my point would be that he knows that he can possibly be deceived. If he doesn’t work from that point, I don’t see how he can get any further than an endless, circular doubt.

Second, the dream hypothesis.

Ironically, those who propound this theory never seem to take it seriously enough. When you’ve been dreaming, most of the time you know your dreaming, but I accept the idea of lucid dreaming – a point for whatever reason where you really can’t tell the difference. I’ve been in one of those dreams where you wake up in the dream and given that it was a RipVanWinkel kind of dream, it was a rather frightening and dismaying experience. Yet, nevertheless, most of my beliefs remained intact, it was not a completely alien world, my wife was twenty years older but she looked the same (and she blamed me for sleeping for twenty years just as she blames me for many things I consider out of my control :slight_smile:), my daughter kept flashing between my picture of her now and my picture as she might be twenty years from now (much like it might happen if it, well, really happened). The point is that if this is a dream right now, it doesn’t change the fact that even in dreams most of your beliefs aren’t questioned. If they were, dreams wouldn’t be interpretable (both in and outside of the dream) and of course they are.

We might even say that the only thing being put into question is the dream/reality distinction. To which my answer is so what? I see nothing foundational to that distinction. That shouldn’t be surprising as I don’t see any particular belief as foundational, I see them as holistically coping with the world. Descartes search for a foundation is flawed because the very search for a foundation seems to me to be flawed, even incoherent when we try to assess the things we actually do to get around in this world.

Less than a hundred years ago we believed in a steady state universe, fifty years ago, we believed in an expanding but slowing universe, we now believe, or many do at least, believe in an expanding but accelerating universe. Is that really any more fantastic than the idea that we live in a dream?

And anyway, last time I checked reason doesn’t account for such things as quantum superpositioning or tunneling.

Third, Matrix.

Enjoyable movie with its flaws and religious overtones (Who exactly is the Oracle anyway?). Look forward to the sequels. But my argument remains much the same. Given the premise that we could be in a computer simulation doesn’t change the fact that most of Neo’s beliefs are still true, it is only the way he received them that is different. They speak English in and out of the Matrix, he has people to help him through the transition, people who are much like the people he met in the Matrix, he still has to eat, he can still fall in love, and perhaps most poignantly for any kind of narrative tension, if you die in the Matrix, you die in the real world.

It really isn’t as staggering as some may think. The effect isn’t a representation of Cartesian thinking so much as caused by Cartesian thinking. If I remember my Celtic mythology/literature class correctly, the idea of other worlds was more or less taken as a given. So a Celt would simply see this as a jump to a different world.

And wonder of wonders, I think it’s clear that Neo already knew something was ‘not right’ with the world. He actually suspected it, and I suppose that many who take this movie more seriously than I do also have that feeling. Contrary to incoherence or destabilization, they might actually feel slightly vindicated. But that just means that one of my beliefs was false, and one of theirs was true. But most of our beliefs in either world are still true.

A far scarier proposition is something like Putnam’s second Twin Earth paradox. There’s a twin earth on the other side of the sun, in all respects the same as this one with one difference suitably adjusted for. Water on this planet is always twenty percent grain alcohol. This doesn’t bother them as their body chemistries are different enough to account for that (and let’s say their science gives them no ability to tell the difference between our water and their water). You are spirited away without your knowledge to this planet and find you are always drunk. At what point, do you stop arguing with other people that they are wrong and start questioning your own sanity?

Most of your beliefs are still true, but you have no way to account for this, not because you are wrong, not because they are wrong, but because you have no way to explain the difference between you and them.

What kind of hell would that be?

Therefore, the demon simply cannot trick me about everything at the same time.


Why not?
After all, even if I do have to accept some propositions as true in order to reject others as false, as you claim, why can’t it turn out that even the propositions I accept as true are, in fact, false. To accept some propositions as true doesn’t imply that they are true.

Furthermore, whatever propositions I accept as true, if the demon makes me believe (as he is supposed to have done) that there is a material world, and if there isn’t a material world, why hasn’t he “tricked me about everything at the same time?” What has to be true (and not only accepted as true) so that the world is not an illusion? It is true that the notion of illusion has to be contrasted with the notion of what is real. But it does not follow that there actually has to be anything real.
To make an analogy. Could all money be counterfeit money? Why not? It may be that we have to accept some money as genuine to reject some money as counterfeit, but it doesn’t follow that the money we accept as genuine is genuine. And it may be that the notion of counterfeit money has to contrast with the concept of genuine money. But it does not follow that there actually has to be genuine money for there to be counterfeit money.

But this is just to place emphasis on the real/illusion distinction, to make it a foundation. Assume everything is an illusion and you’ve really only changed one belief, cats are still cats, hammers still hammers etc… They just are now in a different overall framework. Not too long ago many people thought the Earth was flat or that we were carried by elephants. People accepted the change pretty quickly, but they didn’t plow or measure their fields any differently.

Other than reversing Ryle here, it’s hard for me to understand this. Money is a mind dependent concept. If, I don’t know, the mafia suddenly were able to replace genuine money with counterfeit, I suppose we could be fooled by this, but not without genuine money existing at some point. If money began as counterfeit money, then that would be genuine money or perhaps, more correctly, it’s simply incoherent to say something like that.


My problem begins with your view that what is accepted as true (by everyone? Who?) is, ipso facto, true. To talk about a proposition being “accepted” as true surely leaves room for its not being true. If I accept money as genuine, that still leaves room for its not being genuine.
I never used the word “illusion”. “Illusion” is an internal notion. And of course, cats are cats, and hammers are hammers. But that is only a tautology. But, if, hammers and cats are made up of space time points, they are, of course, still cats and hammers, but wildly different from how they appear to be. After all, even if they are "illusions’ they are not hallucinations.

As for genuine money. Genuine money is money produced by and certified by the United States. Now, there could have been a vast conspiracy whereby none of the money we take as money is genuine money. Think of it this way: is Confederate currency real currency? It was produced by the Confederacy, and accepted by people in the South as currency. But is was illegal all the same. Had the colonists lost the war against England, the Continental currency accepted and used in trade would not, well, be worth a continental.

Yeah, I realized what you were shooting for yesterday, tried to post an addition and it didn’t go through (Ah, these things happen.). If I’m right, you accept that we have to believe most of our beliefs our true but that that, by itself, doesn’t mean that they are true. The way we know that they are true is through a process Davidson calls triangulaton (Yep, he means it in the same way we use triangulation when on the high seas before GPS). Because we can be wrong about any one belief we are one point in a triangle with other minds and the external world as the other two. That we can actually be wrong about something presupposes that we can be right and triangulation is the trick that gets us there. For example, we (wife and I) recently watched the movie ‘Dinosaur’ with my daughter. She saw a dinosaur and said the Korean word for horse. We corrected her (though I don’t think it was such a bad categorization), but she wouldn’t have corrected herself if only herself existed, and we wouldn’t have known how to correct her without an external point that we all see.

Ironically, it’s our ability to doubt (more correctly, to be wrong) that gives us the vehicle to know we’re in the real world.

I like that last sentence (illusions but not hallucinations), but I still detect a kind of foundationalist residualism here. I see no reason to choose between different points of view (Is a coin really a circle if looked at a certain way or is it a thick line if looked at another way?). Cats and hammers are wildly different if looked at in different ways but that in no way puts the fact that you know what I’m talking about in question. We can describe them chemically, atomically, aurally, or visually. I see no reason to privilege one over the other.

And that ain’t going to change if we are wrong about what exactly reality is.

I think, as did Wilfrid Sellars, that the “scientific image” of the world is the authoritative description. The “manifest image” is the way, given who we are, we have to see the world, and it enables us to get along in the world (obviously, else we wouldn’t be here.) But the scientific image tells us the truth about cats and hammers, and isn’t that what we are aiming for?

Brad said earlier:

1 and 2 are fine, but 3 is just plain wrong. You can question something without taking anything for granted. You are basing 3 on learning that what you beleived was wrong. If everything you knew might be wrong, it would be impossible to learn that everything you knew was wrong at the same time, but that does not mean that it is impossible for everything you know to actually all be wrong at once, without you knowing it was wrong.

kennethamy,

No doubt, there’s every reason to accept scientific description on any of a number of occasions, but I see no reason to accept it across the board. A variation on Putnam explains it well: you aren’t going to do very well in courting a young lady by explaining that she is really nothing more than a collection of sense data to you.

Or

“Di-hydrogen monoxide, di-hydogren monoxide everywhere and not a drop to drink” :wink:

Mentat Monkey,

I am attempting to describe the nature of doubt. It has nothing to do with whether something is actually true or false (that involves triangulation as explained later). One cannot question without first taking the ability to question for granted (Hell, even Descartes got that one right), but that one acceptance presupposes a lot of other things that you can’t question while you are questioning something else.

Just give me an example of what you mean by

And I’ll change my tune.

[quote=“Brad”]
kennethamy,

No doubt, there’s every reason to accept scientific description on any of a number of occasions, but I see no reason to accept it across the board. A variation on Putnam explains it well: you aren’t going to do very well in courting a young lady by explaining that she is really nothing more than a collection of sense data to you.

Or

“Di-hydrogen monoxide, di-hydogren monoxide everywhere and not a drop to drink” :wink:


Well, of course. And neither is it a mistake to talk about the setting sun despite the fact that we are all (I hope) copernicuns. As Berkeley said, “Speak with the vulgar, but think with the wise.”


How, can anything, let alone, everything, you know be wrong? If you know it, then you can’t be wrong. That is one of the differences between knowing and believing.

Of course, to take something for granted doesn’t mean you are right to take it for granted. You may take something for granted, and be wrong to do so. Alas!

Now, let’s take Descartes’ own doubt, that there is a material world “external” to the mind. That the world is a kind of hallucination caused by the Demon. I don’t see right now what I have to believe to have that doubt. I suppose I have to believe there are hallucinations, and there are doubts. But that doesn’t seem to me germane to the doubt about the world. Perhaps it will be said that to believe there are hallucinations I have to believe there are real things. I don’t see that. Perhaps I have to believe there might be real things, but that only means I have have to have the concept of a non-hallucination. Is that all there is to Brad’s claim?

I’m not sure if this will add anything to the discussion, but maybe Brad’s claim is similar to some medieval arguments concerning the nature of God, in that we can know through negation; and that having the ability to know that something is false in the world at least requires that you aren’t doubting that what you ‘know,’ is in fact false about the world? so in order to doubt, you at least have to assume that you can doubt?

But Brad, doesn’t any argument about how we know or about reality itself involve at least one presumption to base the argument upon? And can’t that in itself always be questioned?

No, it involves many, at least many.

Again, I ask that what you say be tested. What we doubt, what descartes does is really only doubting one thing.

Yeah, I admit enjoying stating the obvious. Every once in awhile, you get someone who says, “I never saw it like that before”. We do have a culture, civilization that, to some extent, avoids the obvious in search of the secret.


I don’t understand your reply. You did not state the obvious. I disagreed with you. I pointed out that although (here is another example) we do not say, “Please pass the NCl” when we say, “Please pass the salt,” that is, in fact, what we are saying. Do you agree?

Huh? You disagreed with me? Well, okay. I guess I misunderstood that ‘of course’. It does nothing to salt to describe it as salt or as NACL. The appropriateness of any description depends on ‘our’ goals, not on the essence of salt.

I thought about going after ‘wise’ but changed my mind. I guess I should have. There is no outside point of view, no skyhook, no way to have a view from nowhere. The wise are not more in touch with reality, we are all in touch with reality. We just describe it differently.

It occurs to me that Plato’s Allegory of the Cave might illuminate the issue. Take the position of the prisoners facing the inner wall of the cave and watching only the shadows of the real objects passing outside of the cave. So far as they are concerned, the shadows are the reality. Now, that there are real objects outside the cave is true, but the prisoners don’t know of them. Some great metaphysician among them might speculate that perhaps what they see is not real, and that there is a reality somewhere, but that does not mean he believes in the existence of that reality. He has only the concept of such a thing, and perhaps he dismisses it as a fantasy. What he believes is that the shadows are real.
So the question is, what must that metaphysician believe is true to doubt that the shadows are real? Nothing, that I can see which is germane to the issue.


I do disagree, and I think I understand you.
Why is the scientific image superior to the manifest image, to use Sellars’ language?
Because we can explain the manifest image in terms of the scientific image, but not vice versa. For instance, we can explain why (and how) the manifest image is the manifest image: Why a world of electrons and other microparticles whizzing around at enormous velocities appear as middle-sized objects to us. But we cannot give an explanation the other way round. To put it a bit differently, we can understand the manifest image in terms of the scientific image, but not vice versa. And, of course, we can do other things with the scientific image that we cannot do with the manifest image. For instance, we can get (or at least try to get) a picture of the whole, how, for instance, electricity works with (maybe) gravity.
I don’t think that the scientific image is a “skyhook” in anything like the sense Davidson means that. The scientific image integrates the manifest image and connects with it. It is a picture of the world from within, but a superior one.

But this is just confusing speculation with doubt. If he believes the shadows are real, he doesn’t doubt them. I’m certainly not trying to make a case against speculation – that would turn my points away from the sceptic and toward fiction. I certainly don’t want to deny that fiction exists.

Gotta go, wife says she’s hungry. :wink:

Let me try to expand on that. What Descartes says is that if it is possible to doubt something, it must be rejected as a foundation for certainty. What I say following Davidson is that it is not possible to doubt something without at the first time believing in many other things.

Plato, or rather the great metaphysician, doesn’t really doubt that the shadows are real, what he thinks is that there is another world, presumably the world that casts those shadows on the cave wall (which he doesn’t doubt, nor does he doubt the imprisonment of those other, less gifted, metaphysicians) that is somehow realler than the real shadows. That is, that we’re not getting the whole picture. The doubt therefore is really only one doubt, doubting whether what we see are shadows of another world, but those shadows, in order for them to be shadows, must be just as real as, well, the real world.

In other words, I think Plato and Descartes are really talking about two different things. It’s certainly okay to speculate, it’s fun too, but if we’re going to take those things seriously, as a useful description of the world, we have to examine the nature of doubt and this is not something Descartes does.

I think.


Whereas you use Plato’s cave as an example, I think he set the terms of the debates as Descartes did at a later stage. They didn’t recognize the problem so much as create the parameters for the problem in the first place. I see no reason to accept scientific description as superior in all cases, or as you put it

But why is it superior? Is it superior because it is a more accurate description? I do not see how we can compare descriptions in this way unless we posit the very thing we’re trying to describe, that we already know the thing we’re trying to measure and can test it against what we already know is the real world. That is, of course, exactly what we do, but it’s not between the world and our description, it’s between two different descriptions.

Rather than deal with these problems why do we have to posit a privileged description for everything at all (We do, I think, because we still follow Plato in some sense)? Why not see these descriptions as useful for certain purposes and not for others, or why not even see them as different languages?

If looked at this way,

is like saying that we can translate from Chinese into English but not vice versa. As I write that, I immediately think of the notorious difficulties of translating Joyce’s ‘Ulysses’ into Chinese. So, yes, some languages are more useful than others for certain purposes, but I don’t see how that makes translation impossible.

Just difficult.

And besides, I think many scientists have made great efforts to explain science in manifest images so that those who do not speak their language can understand what they are doing (Are popular science books really a fool’s errand?).

I’m confused here (that should be obvious by now). You say we can’t explain how electrons and micro-particles whizzing around at enormous velocities with middle-sized objects. But isn’t that what you just did? Whizzing, velocities, particles (and waves, strings, slingshots, bubbles, etc) are all references to middle-sized objects. Newton didn’t invent the world ‘gravity’, he used gravitas as a metaphor.

It’s interesting that you would use physics as your example here. That was, no doubt, the paradigm field of the twentieth century, but many have pointed to a shift in thinking here, to a biological paradigm in the twenty-first and sure enough we have theories that explain physics (why the universe is the way it is) in terms of evolution.

Now with all that said, I don’t want to be misunderstood as being anti-science. I’m not, but I can’t help but wonder if by placing it on a metaphysical pedestal, we don’t inadvertantly set it up for a fall. Scientific description’s greatest strength is its ability to change based on results (as opposed to sheer force), but that makes it a very difficult standard bearer of certainty.