Study Guide

Week Five: Descartes’ Foundationalism - Rebuilding Knowledge from the Foundations

1. Materials Assigned for the Week
2. The Central Point of This Week's Material
3. Other Concepts and Points you are Expected To Master This Week
4. Miscellaneous Comments and Clarifications
   1. What Happens After the Existence of God is Proved?
   2. The Real Source of Human Error: Meditations Four and Six
   3. Descartes’ argument against scepticism: Meditation Six
   4. The "Cartesian Circle": Meditations Three and Six
   5. Three Special Cases for Advanced Readers: Meditation Six

I. Materials Assigned for the Week

Reading:

Lecture 13: Descartes' Foundationalism (concentrate on pp. 169-174)
Readings: Descartes, Meditations on first philosophy, Meditations 4-6, pp. 232-251 (again, pace yourself!)

Exercises:

Review Questions: pg. 174
Problems for Further Thought: pg. 175

II. The Central Point of This Week's Material

Once the "foundations" of knowledge have been laid clear, then further claims about the world of everyday physical objects can be "built up" upon them. These will count as genuine knowledge in the sense of being true beliefs reliably justified. Building up such knowledge requires a proper understanding of the real sources of human error; a proper understanding of the human faculties of understanding, imagination and sensation; and in particular a proper appreciation of the boundaries beyond which sensation cannot be reliably pushed. These are summarised in Descartes' final bridging principle from "inner" to "outer":
"Clear and distinct ideas are true".

III. Other Concepts and Arguments You Are Expected to Master This Week

• What the so-called "Clear and Distinct Ideas Principle" is - if it's not yet plain enough from the definitions of Week Four - and especially why Descartes thinks it successfully bridges the "inner" / "outer" gap
• How Descartes' final proof goes that we can have knowledge about things like tables and chairs and cats and dogs - best as always to practice it using an example
• What the so-called "Cartesian Circle" is, and why it is a special problem for any foundationalist response to scepticism
• The difference between the mental faculties of understanding (making judgements as to truth and falsity) and free will (making free choices)
• The difference between the mental faculties of imagining (e.g. a triangle or hexagon or chiliagon) and understanding (their real geometrical properties through the intellect)
• The difference between imagining (actively fashioning an image) and sensing (passively receiving an image)
• The role of freewill in human error - Descartes nearly goes so far as to say there is no other source of error, even with judgements about ordinary physical objects - than our freely choosing to push our mental faculties beyond their proper boundaries!
• The difference between the claims that we are essentially non-physical thinking beings (Meditation Two) and the claim that (nonetheless) there exists a "substantial unity" between our minds and our bodies (Meditation Six) - this is perhaps too subtle, and difficult, to spend too much time on.

IV. Miscellaneous Comments and Clarifications

IV.A What Happens After the Existence of God is Proved?

Descartes finishes proving the existence of a perfect God in Meditation Three. But he doesn't think he has answered the sceptic's challenge until the end of Meditation Six. Why does Descartes need three more chapters - and especially convoluted chapters at that? Sober understandably shortcuts most of this additional stuff and says that the non-deceptiveness of God guarantees that clear and distinct ideas are true and more or less leaves it at that (pp. 173-174). You are not required to go beyond Sober's shortcut of course - Sober is the textbook after all. But I have asked you to read those three additional chapters of Descartes; so I owe you some rough sketch of what they are there for, and what they add to Sober's quick summing up.

Achtung!

Understanding this section is optional. But I would strongly advise it to anyone who is feeling lost and desperate.

Happily, I am not talking about anything particularly exotic or even very hard to understand. The material in Meditations Four through Six is driven in a very natural way by the precise sort of worry which Descartes' sceptic is running. The sceptic argues that we can not provide proper justification for knowledge claims about the physical world because it is always open for us to make mistakes about them - only knowledge of the contents of our private subjective experience is incorrigible. Such a sceptical worry about what is ultimately responsible for the mistakes we make won't be laid to rest until we come to a proper understanding of the real sources of human error and hence come to a proper understanding of the ways to circumvent such errors. Specifically, Descartes insists, we must realise that human error is not after all the result of trickery by some superior power (which presumably we could never escape), but entirely the result of ourselves misapplying our own freewill (which we therefore have some hope of detecting and stopping).

Here then is the plot line of the rest of the Meditations.

1. A perfect God exists. That's what we can count on having established by the end of Meditation Three (pg. 232).
2. Because God is perfect, God is not a deceiver. Deception is an imperfection and the supreme being has no imperfections but is perfect in every way possible (pp. 232-233).
3. Therefore the Evil Genius does not and cannot exist. That is, what we so casually took to be at least a thinkable hypothesis in the thought-experiment of Meditation One turns out to be a logical impossibility (cf. a square circle). The existence of a perfect God and a deceptive Evil Genius are logically incompatible.
4. Therefore the mistakes which human beings make when they argue from "inner" to "outer" (from private subjective experiences to public physical objects) cannot be explained as the result of some super-power exercising ceaseless but undetectable trickery over us. There is no such being, so there can be no such wholesale trickery.
5. Errors and mistakes must therefore be explained entirely in terms of human abilities which we misuse, whose misuse is detectable by us, and which it is possible for us to stop misusing. Specifically, Descartes argues, such error is the result of our misusing the faculty of free choice which God created us with: we freely choose to push our God-given mental faculties of intellect and sensation beyond their natural limits, and when we do of course they give us erroneous results (pg. 235). For this misuse of freewill we alone are responsible, not the perfect God who bestows us with those faculties of mind, and not some Evil Genius who tricks us about them. In this analysis lies our eventual salvation too. Such wilful misuses of ours must be detectable by us and correctable by us - or else the God who created us with such faculties of mind as freewill and intellect and sensation would be ultimately responsible, and hence a deceiver; which we have already proven is God is not. All we need to do is work slowly at detecting the proper limits of intellect and sensation, and then make the free choice not to push those faculties beyond those limits.
6. This analysis immediately removes our earlier hesitations about employing descartes' "clear and distinct ideas principle" - the principle that clear and distinct ideas in our mind deliver truths about the public world outside of our minds. Those hesitations were first broached against such ideas as "the earth" and "the heavens" and "2 + 3 = 5" in Meditation One (pp. 216, 223-224) and rephrased in a wholesale way at the beginning of Meditation Three (pg. 224). The hesitation is this: the Clear and Distinct Ideas Principle is unreliable so long as it is logically possible that an Evil Genius exists, intent upon tricking us in every way it is logically possible for us to be tricked. For, of course, that might be the very thing he is most intent to deceive us about - that our clear and distinct ideas are true when they aren't. Any such hesitation goes for good. We have shown that the Evil Genius is not a logical possibility (Step Three), and we have shown that our own misuse of freewill is the real source of human error (Step Five).
7. Therefore the clear and distinct ideas principle is indeed true and known to be true (pp. 236-237). If the mere idea in my mind that X is clear and distinct, then it is true of the public physical world that X. I can reliably infer from the existence of some idea in my mind to the existence of the relevant physical object or situation in the external world - provided that that idea in my mind is clear and distinct. Such a Clear and Distinct Ideas Principle is thus exactly the bridging principle which Descartes said he was looking for and which allows us to go reliably from "inner" to "outer". Therefore the sceptic's claim that there is no way to go from "inner" to "outer" is refuted.
8. In many important cases, however, the ideas in our minds from which we want to infer the state of the world outside our minds fair to be wholly clear ideas or wholly distinct ideas. For them the Clear and Distinct Ideas Principle will obviously not take us anywhere close to where we need to go. In Meditation Six, Descartes supplements his key principle with a few other principles which will deliver knowledge of the world outside of our minds in special circumstances (pp. 246-251).

IV.B The Real Source Of Human Error: Meditations Four and Six

The real source of human error has never actually been undetectable deception by some Evil Genius or the like, but the simple fact that we possess the faculty of freewill and freely choose to misuse it! When Descartes first broaches this startling idea (pp. 223-236), he has already proved the existence of God and stated that God has bestowed upon us several mental faculties: sensation, imagination, emotion, understanding, deliberation and the like. Accordingly, if I used any faculty which God gave me only in the way in which God designed it to be used, then I could never make errors (pg. 235) - or not anyway through my use of that faculty. Error comes in because another of my God-given faculties - freewill - has no natural boundaries. Freewill couldn't have boundaries to its application like the other faculties have, of course, or else it wouldn't be a faculty which was truly free - freedom circumscribed isn't freedom at all. [More of this in Week Eleven.] Now, if by using my freewill I freely choose to overextend one of my other faculties beyond its proper boundaries, then I have in effect freely chosen to push that faculty into areas where it is incompetent to act. Of course errors will happen then. And when they do it's down to me, not down to some hypothetical Evil Genius, nor down to a perfect God.

Take three of the faculties prominent in Meditation Six as examples of faculties with boundaries or limits to them. Used inside of those limits they provide reliable results. Used outside of those limits they don't. Think of a simple thermometer too [compare the discussion of "Circumstantial Reliability" as a definition or theory of knowledge in Week Three].

• Example: The faculty of the intellect or understanding, Descartes says (pg. 233), has been designed to deal with ideas which the mind can apprehend the whole of and unmixed with any other. When the intellect is turned upon other mental contents than such clear and distinct ideas (when it is turned upon images or emotions, say), then these other ideas are beyond its proper scope, it is out of its depth, it can't cope with them. Just try to apply the faculty of intellect to the smell of a rose. Try to use the intellect on the smell of a rose and any conclusions you draw will be simply ludicrous. We wouldn't expect otherwise.
• Example: In exactly the same way, the faculty of imagination (pg. 242) has been designed to deal with ideas that are images. Imagination is basically image thinking (though there are occasionally exceptions). When the imagination - image-thinking - is turned upon other mental contents than images (when it is turned upon definitions and concepts, say), then these other ideas are beyond its proper scope, it is out of its depth, it can't cope. The results will again be ludicrous. Just try to apply the faculty of imagination to determine the difference between the image of a 999-sided figure and the image of a 1000-sided figure. It can't be done. You just can't discern an image-difference between those two images; the faculty of image-thinking just doesn't stretch that far. By contrast, the faculty of the intellect can determine perfectly adequately that there is a difference between those mathematical figures and exactly what those differences are (for instance, each facet will have a different number of sides and angles - I believe a chiliagon is made of hexagons for instance).
• Example: The faculty of sensation too, according to Descartes, has proper limits (pg. 243). Sensation is the faculty he spends most of his time on in Meditation Six. According to Descartes, the faculty of sensation has been designed (by God of course) to deal with ideas that force themselves upon my mind and can't be prevented entry merely by my wishing or willing them to go away. When sensation is turned upon other mental contents (upon worries or memories or non-images, say), then these other ideas are beyond its proper scope, sensation is out of its depth, it can't cope, delivers crazy results. Just try to apply the faculty of sensation to determine whether such and such prime number is the highest one in the series or not. Indeed, try to use sensation alone to determine whether the series of prime numbers is infinite or not. Of course if can't be done. Numbers in general are not images forced into the mind against our control anyway. And even if they were, we certainly passively receive only the teensiest fraction of prime numbers there must be for any image-thinking to work effectively on.

Several obvious notions come together here, applicable to all the various mental faculties:

1. Each of the faculties of the mind has limits or boundaries to its application. (Nothing la-di-da here. Compare a simple food mixer. By its design, a food mixer makes nice cake dough, but it won't drive you downtown or iron your clothes.) Used within its natural boundaries, the faculty is used as it was designed to be used and functions improperly. Used outside its boundaries, however, the faculty is used improperly and against its designed purposes.
2. For the arena of the "inner" which still concerns Descartes and any Foundationalist, the boundaries of the mental functions are typically set by the kinds of ideas which the faculty has been designed to handle. So applying some faculty to the wrong sorts of ideas is the main cash value of "applying a faculty improperly".
3. Applied properly, to the right sorts of ideas (that is, to the kinds of ideas it was designed to handle), a faculty does not deliver errors.
4. Applied improperly, to the wrong sorts of ideas (to those it was not designed to handle), any faculty will be quite unreliable. And this unreliability will not be an especial flaw in that faculty, for all faculties have natural limits and boundaries to their proper use. [For example, a rectal thermometer won't work on the sun. Of course.] The unreliable results obtained when using some faculty improperly are not down to that faculty. [It's hardly a deficiency in mercury thermometers that mercury is no longer a liquid at the sun's temperature.] The unreliable results are squarely the responsibility of the user of that faculty. [What idiot thought rectal thermometers ought to work everywhere?].

When we freely choose to push such God-given faculties as the intellect or imagination or sensation beyond their proper limits - that is, when we apply them to the wrong sorts of ideas in our minds - then naturally enough we are going to make errors all over the place. When we freely choose not to do so, then we do not make errors. [For if we still did, then that would be down to God. And God is not a deceiver. Blah blah blah.] So actually free will is at the root of it all. The Evil Genius never actually had any part to play!

That gives the broad idea. We must slow down even more for the details. The sorts of cases in Meditation One where the sceptic undermined Descartes most convincingly were mistakes of perception. That is, cases where we make wrong judgements about the contents of world "outside" of our minds on the basis of the contents of the perceptual experiences we have "inside" our minds. For instance, when I judge that I am typing away on an off-white keyboard on the basis of my being conscious of off-white patches of colour and feelings of pressure. If this is the main battleground, we must be especially clear what the proper boundaries of our God-given mental faculty of sensation are supposed to be for Descartes.

Sensation is the entirely passive reception of images by the mind. The key fact about sensing is that I am not myself responsible for the presence of such images. They are forced upon my mind, intruding, as Descartes puts it, "without my co-operation and sometimes against my will" (pg. 246). They "come upon me without my consent" (pg. 244). Such intrusion is quite the opposite of those images which I fashion myself and have complete control of in imagining (imagination is an entirely different God-given mental faculty). For example, when you sense this piece of paper you are reading - as opposed to imagine it later on - your mind is downright compelled to receive the ideas you do whether you want them or not: you may prefer to have a sensation of red, or no sensation at all, but a white image is what you get. This compellingness of the ideas his mind comes to have when he senses is the defining characteristic of the faculty of sensation (pg. 246).

Descartes even produces a little proof in Meditation Six that such compellingness is not a feature of how some of our ideas merely appear to us "from the inside" as it were. The compellingness of ideas in sensation is a real phenomenon, a feature of how the world itself is actually constituted (pg. 246):

• Premise 1: I experience that my mind is passive with respect to certain ideas in it. (That is, I experience that some of the ideas in my mind I am compelled to have and are not in my power to resist having.)
• Premise 2: I call this passivity "the faculty of sensation" or "sensing". And I call the ideas in my mind in which I am passive "ideas of sensation" or "sensations".
• Premise 3: God created me and everything else in the universe (proved from God's omnipotence) and in creating me gave me an overwhelming temptation to believe that I am passive about some of my ideas and active about others (Premise 1).
• Premise 4: If God had somehow done away with such passivity but kept me from knowing that he had - that is, if God gave me no trustworthy means to tell that I actually was passive when I felt I was and actually was active when I felt I was - then God would have created me a being deceived from the word "Go".
• Premise 5: God is not a deceiver (from Meditation Three).

therefore

• Conclusion 6: The passive faculty of sensation really does exist and I really do have passively received ideas in my mind.

By now it should be obvious why Descartes makes the faculty of sensation the centre-piece of Meditation Six. In order for me to possess the passive faculty of receiving ideas - as it has just been proved I do indeed possess - something other than me must possess the active faculty of producing such ideas. Once this general principle is established, the problem of determining which specific physical thing is the active producer of which passive idea I receive in some perceptual situation can be tackled on a case by case basis.
Here is where Descartes' Clear and Distinct Ideas Principle comes to bear.

My mind is passive in sensation. So whatever thing possesses the active faculty of producing the ideas which I passively receive in sensation, it must be some thing different than my own mind. We might usefully recall the causal principle of Meditation Three:

"The cause of any idea must possess at least as much formal reality as that idea has objective reality" (pp. 226-227).

This means that the active producer of my passively received idea (my sensation) must lie "on or above the line" on the "formal reality" side of the "objective reality" / "formal reality" box [see Week 4 IV.D] which means my sensations must be caused by a physical body of some sort, or else by a "creature more noble than a body" such as an angel, or else by God. It has been proved that God is not a deceiver, but he certainly would be a deceiver if he created me, produced every image of a physical object I received, stuck me with an overwhelming inclination to believe all such images were produced by physical objects, and doomed me to be forever unable to tell the difference. God would be just as much a deceiver if he allowed his angels to pull off the same trick. So the active producers must lie exactly "on the line" and not anywhere above it. We aren't required to go to anything as strong as Descartes' Clear and Distinct Ideas Principle to know merely that physical objects of some kind or another are the causes of my passively received ideas of physical objects (pg. 246). To know that, however, is not to know very much.

What we really want is knowledge that exactly this kind of physical object is the cause of exactly this passively received idea or sensation. Here nothing less than the full-bore Clear and Distinct Ideas Principle will deliver the goods. The non-existence and non-deceptiveness of God underwrites that principle in its most general form:

Those ideas in my mind which are clear and distinct are guaranteed to be true

The existence and non-deceptiveness of God likewise underwrites the modest extension of this principle to the images I passively receive in sensation (pg. 246):

Those passively received ideas of sensation I have which are clear and distinct are guaranteed to be true

That is, whatever clear and distinct ideas of physical objects I passively receive in my mind have been caused to get there by physical objects which are exactly similar to those passively received ideas. God guarantees this.

• Example: Suppose that I sense a three-sided physical object whose longest side is opposite its largest angle - that is, I passively receive an idea of a three-sided figure whose longest side is opposite its largest angle. Then I can rightly claim to know that that idea was caused by a actually existing physical object which has three sides and that its longest side opposite its largest angle. Why? Because the idea of a three-sided figure with longest side opposite its largest angle is a clear and distinct idea. Indeed, it is simply the idea of a triangle. And the idea of a triangle, however it got into my mind, is a clear and distinct idea (Meditation Five, pp. 238-239). The special point that Descartes is making in Meditation Six over and above what he said in Meditation Five is concerned exclusively with the faculty of sensation - passively received ideas - which he has now put under his microscope. God has granted me the power to tell when I passively receive (sense) the idea of a triangle and when I actively create (imagine) the idea of a triangle. [God must have granted me this or God would still be a deceiver - see the proof just above.] So on those occasions where I freely choose to use that power within its proper boundaries and I determine that my idea of a triangle has indeed been passively received, on those occasions I can reliably conclude that an actual physical triangle produced it.

On the other hand, this is not quite a guarantee that we never go wrong. It's just a caution that when we do, we can't put the blame on some super-power tricking us in ways we are powerless to detect, for there are no such super-powers. Instead, we have only ourselves to blame when we make mistakes. And mistakes are something we do obviously makes lots and lots of the time. But - Descartes' key point - we make them only when we freely choose to misuse our abilities. For instance, we make mistakes whenever we freely choose to misuse our God-given ability to detect passivity from activity, and start to reason from the occurrence of an idea of imagination which we ourselves have actively produced rather than from the occurrence of an idea of sensation we have passively received. Presumably this is what happens when we frighten ourselves silly telling horror stories at night. Likewise, we also make mistakes whenever we freely choose to apply our intellect upon a passively received idea which is beyond the boundaries of our intellect to handle - namely any idea which is not clear and distinct. Presumably this is what lies behind the teacher's warning never to rely too heavily on how the diagrams drawn on the board in geometry classes look (for they make draw irrelevancies into the proof). Happily, because this is trouble entirely of our own devising, it is trouble which we ourselves can prevent, by freely choosing to reign back our use of intellect only to ideas that are clear and distinct.

IV.C Descartes' Argument Against Scepticism: Meditation Six

There is a truncated version of Descartes' final deductive argument in Sober, pg. 173.

The Logical Form Of Descartes' Foundationalist Answer To A Sceptic

Here is basically the same argument "stretched out" on a slightly longer table. I try to make more explicit some of the points of logical structure upon which the whole pivots. You can do even better by further substituting meaningless letters for items of content [see Week 2 IV.C]. Once you know the structural plan or "logic" of the thing, you can more easily test that structure for validity, and you can more easily fill in the rest under emergency conditions (exams, self-checking, tutorials, defending yourself and the like).

• Premise 1: Some of my private conscious ideas (images, experiences, beliefs) are clear and distinct, and other of my ideas are not clear and distinct. (That is, this is not a "Just So" fiction [as it would be for the various brands of "materialism" discussed in Weeks Eight to Ten]; we are speaking to a genuine characteristic of genuine things.)
• Premise 2: Clearness and distinctness in ideas is a purely subjectively determinable property of those ideas. (That is to say, ideas in my mind can be distinguished by me as subjectively clear and distinct ideas versus subjectively not clear and distinct ideas, purely "from the inside" as it were, by my just looking at them closely to see if any other ideas are mixed in with them and so on [see Week 4 IV.C].)
• Premise 3: God exists and is no deceiver. (Proven elsewhere.)

therefore

• Conclusion 4: The ideas I have which are subjectively clear and distinct must be true of the public physical world as well. They must deliver truths rather than falsehoods about the world outside of my mind. (Otherwise God would be a deceptive being after all - presenting me with ideas that are subjectively clear and distinct and yet systematically out of whack with how the rest of the world actually is.)

therefore

• Conclusion 5: Whatever clear and distinct ideas I have inside my mind furnish me with infallible evidence that the world is as I conceive it to be in my clear and distinct ideas.

therefore

• Conclusion 6: Plugging all this into the "strong" definition of knowledge [see Week Three], whichever true beliefs about the world outside of my mind which I base on the clear and distinct ideas present in my mind satisfy the most stringent conditions for knowledge about that world.

This is a nifty argument. It has many more virtues than it may seem at first glance. For a start, it is a valid deductive argument - no prize to be sneezed at. But even more important, Descartes seems to be tackling the sceptical problem: "How can you get from the inner to the outer?" in exactly the right way. The argument has the right "feel" to it.

What Descartes does is first identify a purely inwardly-detectable property which certain of our inner contents have ("clearness and distinctness"). Then he shows that inner contents which possess that special property must also possess another, outwardly-directed, property. They must be true of the world outside of the mind. What guarantees this is the proven fact that a perfect God exists and therefore an Evil Genius cannot exist - since it is possible for an idea in the mind to have the first of those properties but not the second only in a world where a systematic but undetectable deceiver is running amok (or where God is that very deceiver). This is the pivotal result of the Meditations. It can now be expressed as the general rule "clear and distinct ideas are true" - namely the rule I have been calling Descartes' "Clear and Distinct Ideas Principle". Moreover, Descartes can now rightly claim to know that this rule is absolutely reliable (because, once again, it could be false only if some super-deceiver still lurked, which is logically incompatible with God's existence). Armed with such a rule, we have finally got our hands on precisely that bridging principle between "inner" and "outer" which will reclaim most of the beliefs we earlier had to set aside. To be sure, knowledge about any matter which goes over and beyond those of our private "inner" mental ideas which form the foundations of knowledge will not count as "foundational" knowledge. But based as it is in canonical ways on canonical foundations, it does constitute knowledge about the "outer" public physical in some fairly robust sense of "knowledge" - "justified true belief" about the contents of the world at large beyond our individual souls.

The sceptic's overall charge was to claw back our shared world, when each of us was forced to start anew at the solitary subjective world of our own conscious experiences. The Foundationalist has now done exactly that.

An Example of Such An Argument Against Scepticism of the Senses

The best way to assess whether Descartes' final argument is actually going to make any impact against the sceptic who has been running him ragged, is to fill in to logical form of the wholesale argument with a specific example. This is exactly what Sober does on pg. 173. In fact, he actually discusses the more general form of Descartes' argument only after presenting his sample case (bottom of pg. 173 to top of pg. 174).

• Premise 1: Right now I have a clear and distinct idea in my mind - i.e. a purely "inner" experience - that I am pounding away on an off-white keyboard.
• Premise 2: Clear and distinct ideas are true.
therefore
• Conclusion 3: I have justified true belief - i.e. genuine "outer" knowledge - that I am actually pounding away on an off-white keyboard in my study.

Think!

Is there anything wrong with Descartes' argument?

• Does its general logical form work all right?
• How about the specific applications to individual cases?

Sober thinks there is something fundamentally awry with every kind of Fundamentalist argument against scepticism of the senses, large or small. Many others agree with him.

IV.D The "Cartesian Circle": Meditations Three and Six

The problem lies with the "Clear and Distinct Ideas Principle" that appears in Premise 2 and which seems so invulnerable:

Clear and distinct ideas are guaranteed to be true ideas as well.

First Problem

We are supposed to rely on this principle only after we have proved the existence of a non-deceptive God and therefore the non-existence of any Evil Genius. Ultimately, that is, it is the non-deceptiveness of God which underwrites the Clear and Distinct Ideas Principle: it is because God exists and because God is non-deceptive, that God stands behind the veracity of any of our mental contents which are clear and distinct. Unfortunately, however, it is not as plain as it needs to be that Descartes hasn't somewhere had to sneak in exactly the Clear and Distinct Ideas Principle he wants to prove earlier on than the conclusion that God exists and is non-deceptive. In particular, Sober is suspicious that Descartes might be using that very Principle in order to prove that God exists, only to turn right around and use the conclusion that God exists in order to underwrite the Principle.

It is not all that easy to tell whether this suspicion is on track or not. After all, Descartes' proof is long and complex [rehearse Week 4 IV.D for a moment]. It takes for granted that a huge number of distinctions are drawn at exactly the right places (e.g. between "thing" and "idea" in general, and specifically between "the supreme being God who is present throughout the universe" and "the idea of God I have in my own mind"). It draws upon lots of other concepts many of which no longer work for us exactly as they did for Descartes (e.g. that reality comes in "grades" and that different existing things can possess different "amounts" of reality). It requires unquestioning acceptance of other axioms that we aren't quite so confident are true (e.g. "every idea that exists in the mind must have been put into the mind by some cause or another"). It invokes an increasingly arcane procession of causal principles which are by no means obvious to anyone anymore (e.g. "an event or state can be caused only by a cause which possesses at least as much reality as its effect possesses", "an idea can be caused only by a cause which has at least as much formal reality as that effect has objective reality", and so on).

When push comes to shove, can we be absolutely sure that Descartes has more justification up his sleeve for such bits of apparatus than: "I have a clear and distinct idea that so and so"? If Descartes ever argues in this way, even once, then he has used the principle "clear and distinct ideas are true" in order to arrive at the very materials which he needed to assemble before he could prove it!

That would be to argue in a circle. The circle is famous, or more accurately, notorious. It is the so-called "Cartesian Circle", as Sober dubs it on pg. 172.

If Descartes is indeed guilty of committing arguing in a "Cartesian Circle", then his whole proof, of everything, collapses into rubble. The disaster is easiest to illustrate in terms of an example:

• Premise 1: I know that the cause of an idea must have at least as much formal reality as the idea has objective reality because I have a clear and distinct idea that the cause of an idea has at least as much formal reality as the idea has objective reality.
• Premise 2: The truth of Premise 1, together with the truth of a few more similar Premises proves that a perfect God exists.
• Premise 3: Premise 1 and all its mates are indeed true.

therefore

• Conclusion 4: A perfect God does exist.

therefore

• Conclusion 5: It is logically impossible for the Evil Genius to exist, or any other super-power systematically misleading us but doing so undetectably by us.
• Premise 6: The only hypothetical situation or "possible world" [see Week 2 IV.B] in which the principle "clear and distinct ideas are true" could be a false or unreliable principle is one where such a super-deceiver did exist and was hard at work.

therefore

• Conclusion 7: The principle "clear and distinct ideas are true" is indeed true.

Suppose this were more or less the way Descartes justifies his Clear and Distinct Ideas Principle, as Sober suspects. Then his justification of it would be blatantly circular and question-begging. Why? Because in order for Premise 1 to be true, Conclusion 7 has to have already been proved true! If Conclusion 7 is not yet available - which it isn't until it has been soundly deduced - then Descartes in fact has absolutely no reason at all to maintain the likes of Premise 1: "I know so and so because I have a clear and distinct idea in my mind that so and so".

That is the meat of the charge which Sober levels: "Descartes commits the fallacy of the Cartesian Circle" (pg. 172). Whether Descartes actually does commit such a fallacy, that is another matter, and still a sharply-disputed one. I find it rather hard to believe that he did, since arguing in such a circle is such an obvious, and fatuous, mistake for someone as canny as Descartes to make. However, it has to be admitted that Descartes never takes the time to explain why he is entitled to help himself to quite so many of the tidbits he uses along his way; he certainly doesn't do much to dispel such a suspicion.

(Nor is Descartes especially clear even on which position he would prefer to take if he could. For instance, he seems to claim he has the principle firmly available in his toolkit at the beginning of Meditation Three on pg. 223. That would be well before he officially begins the first of his proofs for God. But later he also seems to admit quit openly that he can be sure of its truth and reliability only after God's existence has been proved, in Meditation Five, pg. 241. Once you have finished reading the Meditations, you will have to decide for yourselves.)

Second Problem

There is another obvious oddity about clear and distinct ideas. Isn't it really a rather surprising fact that any of my ideas about the world beyond my private mind should have such a wonderful quality as being subjectively clear and distinct at all? Everything else in my life is such a mess. Isn't it more likely that I have just got carried away a bit. Perhaps I don't have any ideas with such a wonderful property. Indeed, perhaps no ideas whatever have any such wonderful property. That is, maybe I don't actually have any clear and distinct ideas in my mind at all, but it only seems to me that I do - illusions of grandeur come easy. This possibility means that Descartes is required to provide us with some way to tell when an idea in my mind really is clear and distinct rather than it merely seeming to be so. If he can't provide a method for testing this, then Descartes' disproof of scepticism is not going to work against any sceptic who keeps their head. Descartes' Foundationalist Argument will be formally consistent, all right. So he is well past the "First Problem" sort of problem. But that is not enough for Descartes' Foundationalist strategy actually to make the successes he wants of it. Any Foundationalist strategy against the sceptic must not merely be logically impeccable. It must actually generate real progress at the real coal face too. That is, the distinctions Descartes needs must be able to be made by human beings, on the fly, and more or less agreed to have been made by all parties. Sober says that the distinction between an idea which is actually clear and distinct and an idea which is not but merely seems to be clear and distinct at the time, is a perfectly understandable distinction in principle. However, it is not a distinction which any human being can actually get themselves into a position to make reliably. As far as theoretical principle goes: fine and dandy. As far as human practice in sito goes: impossible and unavailable. This is a flaw which must be put down to the failure of Foundationalism, for no one else claims it's do-able even in principle. Sober is discussing this rather more subtle point on pg. 173.

Now, Descartes himself believed that he provided everything which was really needed for a usable division between "seems" and "is", simply by showing that that the existence of an Evil Genius is logically impossible. This guarantees, according to him,

1. that any idea which seems to me to possess the special property of being clear and distinct actually does possess that property - because the only reason we could ever have for thinking clearness and distinctness does not deliver truth would be the machinations of a possible super-deceiver. This hardly delivers anything profound enough to be dubbed a "method" for determining which of some batch of apparently clear and distinct ideas merely seem so and which actually are so - since all of the ones which seem so automatically are so! However, it does deliver a "method" of sorts: once the Evil Genius is out of the story, the way to determine whether some idea possesses the property of being clear and distinct is simply to ask yourself whether it seems to possess that property and then to answer "Yes". If this all looks a bit sneaky, notice that Descartes uses the same reasoning for at least two other special properties of ideas. [Not that using a bad argument three times somehow makes it a good argument of course!] Thus
2. he uses it to test whether any idea which seems to me to possess the property of existing in my mind actually does possess that property. Yes it does, Descartes concludes, because seeming to exist just is the proper test for actually existing for such special items in the universe as mental ideas. Naturally enough, it is not the proper test for all items. It is not a good test for the existence or non-existence of concrete gnomes nearby, nor for the existence or absence of oxygen in the air around me. But it never claimed to be all of that. At most, it only ever claimed to be a proper test for the existence or non-existence of certain ideas in the mind. Applied where it claims to work, it works very well. Concerning the presence or absence of ideas, it is as good a test as we have got. For instance, if it seems to me that I feel an ache, then I do feel an ache, no matter what the state of my physical body might be.
3. Descartes uses much the same "method" to test for the special property of some idea actually being conscious to the mind which has it, as opposed to merely seeming to be conscious. Locke later disagreed with Descartes on this and thought that when in a coma, for instance, our minds we do contain ideas - and proper ideas in every sense of the word "ideas" - even though we are rarely conscious of having them either at the time or later on. Likewise, Freud insisted we could be in a towering rage against our parents, often for years, without ever becoming conscious of having such ideas. By contrast, Descartes stuck to his guns: if it seems that we are conscious of an idea (e.g. the idea of a perfect God), then we are conscious of that idea (and thereby we do know all of its properties qua idea as required for the Meditation Three argument of Week Four).

Question!

Does the impossibility of the Evil Genius actually deliver all that Descartes believes it does? [I don't know the answer.]

Third Problem

The two problems revolving around the "Cartesian Circle" are hard to resolve. But a third problem is not. This is a problem with the sort of sample case with which Sober illustrates how Descartes employs his "Clear and Distinct Ideas Principle" against the sceptic (pg. 173, amplified on pg. 174):

• Premise 1: I now believe that the object in front of me is a page.
• Premise 2: My present belief is clear and distinct.
• Premise 3: Clear and distinct ideas are true.

therefore

• Conclusion 4: There is indeed a page in front of me.

In my illustration of Descartes' final argument against scepticism of the senses, I used much the same kind of case:

• Premise 1: Right now in my mind I possess a clear and distinct idea that I am pounding away on an off-white keyboard.
• Premise 2: Those of my ideas which are clear and distinct ideas are also true.

therefore

• Conclusion 3: I have justified true belief (i.e. knowledge) that I am actually pounding away on an off-white keyboard in my study.

What is the special problem with such cases? The problem is the bland assumption that the ideas inserted at Premise 1 would even count as the sorts of cases which Descartes is calling clear and distinct ideas in his Clear and Distinct Ideas Principle. "Clear and distinct" does mean something quite specific after all.

Refer back!

If you are in any doubts about what this technical phrase means, return to Week Four IV.C, and rehearse the notes there. And for heaven's sake, do it now, before getting further up the creek.

In order for some idea X to be a "clear and distinct idea", or in order for some idea X to be "perceived clearly and distinctly", I must have the whole of some idea X in my mind, and the idea in my mind must have no other ideas Y mixed in with it. Glaringly - and a bit astonishingly - neither of the supposedly clear and distinct ideas in Sober's Premise 1 nor in my Premise 1 come even close to satisfying either of these elementary definitions.

• Has the faculty of sensation somehow ensured that the idea I get of a page in these circumstances is the whole of the idea of a page, with nothing whatsoever of the entire idea of a page left out? That is, is there any particular reason to believe that the idea of a page I have will be a clear idea according to Descartes' definition of "clear"? It is hard to believe that anyone, even a philosopher writing hurriedly and simplistically, would dream this at all likely. The lighting situation is weird. My glasses are bad. I'm tired and rushed off my feet. Most important of all, I only look with my eyes and don't pick up the book with my hands. So the idea which is actively produced by the page and passively received in my mind lacks entirely that here is something with a back side as well as the front side I see. It lacks that here is something with words written on both sides of each such page rather than just on one surface. It lacks that here is something which is usually sewn together into signatures of thirty-two similar pages and then bound between covers of thicker material. More or less, the idea which is forced into my mind in these circumstances is the image of a rectangular shape of a certain size. And not a whole lot more. But that idea is nowhere close to the idea of a page. Indeed, I don't have the whole of any idea in the perceptual case Sober envisages, nor in very many other perceptual cases.
• My idea of a page here fares no better as an obviously distinct idea than does Descartes' idea of the earth. That is, Sober provides no assurance whatsoever that my idea meets Descartes' definition of what it is to be "distinct" for ideas: being exclusively an idea of a page, containing only that idea, with no other ideas than page mixed in with it. Indeed, the circumstances of perception practically guarantee that any idea I passively receive is filled chock-a-block with all manner of further ideas, the package mixed so tightly that the faculty of sensation alone can't usually tell even which of them are extraneous and which are the real oil. When I look at the Sober textbook open before me, maybe I do receive the idea of a thing (namely a page) which is a part of a larger thing (namely a book). Let it be so. But I also have, and apparently passively receive, the idea that here is something newly written rather than centuries old. I have the idea of a thing written by a single author rather than written by two people collaborating together. I have the idea of a thing which I might be able to teach 134.101 extramural students from (this idea fades over time!). I have the idea that here is a thing or part of a thing shipped from the USA in a cardboard box, and late, and in smaller numbers than ordered. And so on and so on. There is nothing particularly "distinct" about any of these ideas, of course, for exactly the same ideas intrude forcibly upon me in heaps of other perceptual situations as well. Not one of them is exclusive to the idea of a page. Not one of them occurs in my mind in isolation from all other ideas except the idea of a page. Ideas of sensation are simply like that. Ideas of sensation, I am tempted to generalise, are therefore simply not the right sort of ideas to ever count as "distinct ideas" in Descartes' sense.

Everything just said about Sober's case of the allegedly clear and distinct idea of a page of a book on pg. 373 can just as well be said about my own illustration of the allegedly clear and distinct idea of an off-white keyboard at the end of Week 5 IV.C. Let us suppose it is true that typing furiously on a computer forces an image of an off-white keyboard into my mind ("without my co-operation and even against my will"); and let us further suppose it is true that in those circumstances my mind is entirely a passive receptor of this image. Nonetheless, such an idea is about as distant from an idea satisfying Descartes' definition of a "clear and distinct" idea as it is possible to get. Typing away furiously, I never receive all of the idea of an off-white keyboard, the whole of that idea with no part of the idea left out. (Whatever that means.) Nor do I ever receive only the idea of an off-white keyboard, that idea exclusively with no part of any other idea mixed in with it. (Whatever that means.)

Possibly the cases in Descartes' Meditation Five stand a better chance of being uncontroversial examples of ideas which are clear and distinct according to the canonical definition of "clear and distinct" - ideas which I have the whole of and unmixed with any other idea. The best candidate he has on offer is probably his case of the idea of a triangle: this is the idea of a three-sided three-angled figure, full stop. It is an idea which I usually entertain solely by the intellect but which I might sometimes passively receive in sensation (pp. 238-239). Just possibly Descartes could even sweet-talk us, momentarily, into believing that the idea of a perfect God is another clear and distinct idea (pp. 239-240) - though this would be more uphill. But against these paradigm examples, Sober's suggestion that the idea of a page of a book would satisfy Descartes' definition of a clear and distinct idea is out and out ludicrous. So too would be any serious proposal that the idea of an off-white keyboard was an example of a clear and distinct idea.

And this ruins the proposed sample illustrations of Descartes defeating the sceptic. Maybe Descartes can defeat the sceptic eventually, in some limited areas. Maybe he can even defeat the sceptic using ideas garnered from perception. But the sample argument of Sober's at the top of pg. 173 and my sample argument a few pages back (just above the head with gears box) are simply horrible examples of the winning argument Descartes thinks he has produced the apparatus to give. In both, any claim that the idea in the mind which is used is a clear and distinct idea is utterly preposterous.

Hard Question!

Descartes never used such jejune examples of the "inner" idea from which the "outer" truth was to be deduced.

• What examples did Descartes in fact use?
• Can you think of better examples?

If you can, that will produce a much stronger argument against scepticism than the childish samples Sober and I just produced.

IV.E Three Special Cases For Advanced Readers: Meditation Six

In most cases we aren't working with ideas that meet the high standards of clarity and distinctness. More accurately, we aren't working with passively received images (sensations) which are clear and distinct. Since the Clear and Distinct Ideas Principle only works for clear and distinct ideas, non-clear or non-distinct ideas seem to offer no purchase for gaining knowledge of their causes in the world outside the mind. Descartes ends the Meditations by pointing out certain special cases in which something less strong than the full-blown Principle will still be strong enough.

Special Case One: Sensations About My Own Body Are Caused By States Of My Body

The ideas which sensation passively receives about my own body are interestingly unlike most of my other sensations (pp. 246-247). This provides them a new kind of justification.

• Example: I passively receive the idea that my physical body is wounded when but only when I also feel pain. Similarly, I passively receive the idea that my body needs food and drink when but only when I fell hungry or thirsty. Compare all this to what happens with a seaman and his ship: When the ship is damaged, the seaman perceives by sight (senses) that the ship is damaged. But the seaman himself does not feel any pain. The only idea present in his mind is the passively received idea that his ship is damaged - and this idea his intellect alone contemplates. When my own body is damaged, however, I do not contemplate intellectually the idea that my body is damaged. I feel damaged. My body's damage pains me. That is, I suffer the pain of my body being damaged.

This huge difference between the ideas which I receive and the ideas which the sailor receives proves that the relation between my mind and my body must be much tighter and more unified than the relation between a sailor and his ship. To be precise, it is so tightly connected that whenever my own body is harmed (or helped), sensation does not merely receive the idea "there is damage", which is an idea that is properly to be contemplated by my intellect. Sensation receives as well the idea "pain" or "hurt", which is a feeling available to be suffered by the faculty of emotion, and not an idea available in any way for inspection by the faculty of intellect . By contrast, whenever the body of the sailor's ship is harmed (or helped), the sailor passively receives only the idea "there is damage". This idea is of a sort available only to the sailor's faculty of intellect; certainly it is never available to the sailor's faculty of emotion. It can only be inspected. It can not be felt or suffered through; even when a sailor possesses the faculty of emotion, still that faculty can never be turned to that idea. The two cases are utterly different from each other, in two crucial ways:

1. When I sense my own body - and most obviously when I sense that it has been helped or harmed - the faculty of sensation passively receives not one but two items of mental content.
2. The second of these contents is not even an idea per se, but a feeling or emotion, engaging a completely different mental faculty than any of those considered anywhere else in the Meditations.

The unique sensations I have of my own body in turn guarantee them a unique reliability:

I can trust what I sense about the state of my own physical body, even when the ideas I have passively received in sensation are not clear and distinct.

Special Case Two: Sensations About Things "pertaining To The Union Of Mind And Body" Are Caused By Those Things

The operative phrase here is "pertaining to the union of mind and body". There is no substantial "union" between the seaman and his ship - which is shown exactly by the fact that when his ship is damaged, the seaman does not feel the damage but can only appreciate with his intellect that damage has been done. But there is a substantial "union" between my mind and my body - which is shown exactly by the fact that when my body is damaged, I do feel pain as well as judge "damage".

The "substantial union" between mind and body opens up a way to justify more physical objects than the box for Special Case One ever could (pp. 248-248). Also trustworthy will be any other judgements I make which: (a) are about that special union of mind and body, when (b) they are based on that special faculty who purpose is to inform me out about my union, viz. sensation. This allows us to back off from trusting only judgements about my own physical body, to trusting judgements about other physical objects as well, provided those other physical objects have some special bearing on ("pertain to") on the union which my body has with my mind. Descartes clarifies with three examples. A judgement which is about things that "pertain only to the mind" would be the judgement that what has been done cannot be undone. A judgement which is about things that "pertain only to the body" would be the judgement that physical bodies fall. A judgement about things that "pertain solely to the union of mind and body" would be that I should flee what brings me pain and pursue what brings me pleasure. Base these judgements on sensations, and the first two won't be reliable, but the third will.

Why? Because sensation is a faculty of mind which, like every other faculty, we possess for a purpose. With the seaman / ship contrast in place, Descartes argues that the purpose of the particular faculty of sensation is not just to deliver truths about my own body, but to deliver truths about any physical objects pertaining to the union which that body has with my mind. [The seaman has no analogous faculty with regards his ship exactly because there is no analogous union between them.] Again as with every other faculty, the faculty of sensation has special boundaries and limits tailored to its purpose, inside of which it delivers reliable results and outside of which it doesn't.

Accordingly, any judgement made on the basis of sensation which is about some matter that does not pertain to the union of mind and body, but pertains only to mind or pertains only to body, automatically steps outside the boundaries for which sensing has been created. When I make any such judgements I am "subverting the order of nature", I will readily make errors, and it's entirely on my head not on God's. This is what happened in the first two examples above. Neither "What has been done cannot be undone" nor "Physical bodies fall" pertains to the matters for which we possess the faculty of sensation; so sensation will not justify them. When I judge "Flee what brings pain and pursue what causes pain", by contrast, "I use the perception of the senses that properly have been given by nature only for the purpose of signifying to the mind what is agreeable or disagreeable to the composite of which the mind is a part". Then my judgement is true.

I can trust whatever sensation tells me about other physical objects than my own body whose character pertains to that special union of mind and body which God has bestowed on me.

Special Case Three: sEnsations About Physical Objects Which Impact On Those Arrangements Of My Bodily Parts "As Are Conducive To The Health Of The Union" Are Caused By Those Objects

This is mouthful. But the idea is really quite simple. Sometimes I use sensation to make judgements for the purposes for which sensation has been created - about matters pertaining to my union - and I still make errors. For instance, when I am suffering from dropsy I sense that a certain drink is refreshing and I enjoy drinking it, but in fact drinking is exactly the wrong thing for me to be doing. The ideas I passively receive (sense) pertain to the union of my mind and my body. I enjoy the drink (through the faculty of emotion). I judge the liquid refreshes (through the faculty of intellect). But the results are all wrong. How can that be so without making God a deceiver? ("A sickly man is no less a creature of God than a healthy one; for that reason it does not seem any less repugnant [to God being perfect] that the sickly man got a deceiving nature from God".)

Descartes' general answer is to argue that the human mind is indivisible (the faculties of intellect and imagination aren't spatially located "parts"), while the human body is divisible (toes and knees and eyeballs are spatially distinct "parts"). The mind is immediately affected only by one of the many parts of the body. This part can be put into the same physical state by any number of arrangements or interruptions to the other parts making up the body. Accordingly, this part can be in the same state, and hence cause the same effect on the indivisible mind, when the other parts of the body are very differently arranged - even abnormally arranged.

Think of a piece of rope which has knots tied in it every so often, at points A, B, C, D, E:

  A   B   C   D   E  

I can make the knot at E move a metre to the left by pulling the knot at A a metre to the left: this will make the knot at B move a metre to the left as well; and then the knots at C and D; and eventually the knot at E. But I can also make the knot at E move a metre to the left by tugging the knot at C a metre to the left (by-passing the knots at B and A entirely). Something like this interruption to the normal physical chain of causes is basically what happens when I am sick or in the other situations where I make wrong judgements about my body. The ideas passively received in my mind are caused there by the usual physical part of my body which causes those ideas, but that physical part itself has been caused to be in its state by an abnormality in the causal chain from the other physical parts of my body [compare tugging at knot C in the rope rather than at knot A].

Descartes explains the general idea with a piece of ordinary human physiology taken from his earlier textbook on the human body, Treatise on Man (1629-33). When the nerves in the foot are agitated (by a flame held against the skin say), that in turn causes a motion in the nerves of the leg, then the spine, then the brain and finally the inner part of the brain called the "common sense". [In the Treatise on Man this "common sense" is identified with the pineal gland; we now know the pineal gland has a different function.] The motion of this inner part is what causes the mind to feel pain. When the mind feels pain, the pain in turn affect the "common sense", which affects the spines ... eventually causing the physical foot to move away from the flame. This arrangement of the parts of the body is conducive to the health of the special union between my mind and my body, and no other arrangement of my bodily parts serves its health so well. God would be a deceiver, then, if he created me the union of a mind and a body but with any less efficient way of protecting its health than this long chain of causation from the foot to the "common sense" to the mind to the "common sense" to the foot.

I can trust those passively received ideas (sensations) as are caused by that arrangement of physical parts which would be most conducive to the health of the union of my mind and my body.

Whatever errors sensing continues to lead us to make here, are made only when, for example, the spinal nerves and upwards are caused to move exactly the same way, but not by the foot's nerves being agitated but by, say, a blow to the spine. Then what happens is that the "common sense" is eventually put into the state where it causes the mind to feel pain, and so causes the mind to cause the foot to move, but there was no danger to the foot at all (only to the spine). It is because God has created me to be the union of a mind and a body, and because it is the nature of my body to have spatially distinct parts causally connected to each other, that such an error can occur and I be deceived about what is happening to my foot. However, if my spine suffers a blow and I move my foot, that error is not to be put down to God deceiving me. It is to be put down to the essential natures of the two substances of which I am the union (specifically, to the indivisibility of my mind and the divisibility of my body).

This consideration offers a way to detect and prevent such errors too: when my body is being stimulated in some non-normal place or part. My body is being stimulated in just such a "non-normal" part when it suffers a blow on the spine. The "normal" part for the initiation of the relevant agitations in my spinal nerves is my foot. What counts as "normal" and what as "non-normal" in these matters can never be determined reliably from just one sensation, of course. But since it has been proved there is no global deceiver like the Evil Genius, and that God has created me to be a uniquely tight union of mind and body, there is no particular reason to believe that the "normality" and "non-normality" of the bodily side of the causal chain of my passively received ideas will somehow be completely beyond my powers to determine. I simply use my other senses and my memory and my intellect to check sensations against each other until I have built up a fuller picture.

This is Descartes' final rebuttal of wholesale scepticism. It is also a remarkable anticipation of the situation-sensitivity you will remember proclaimed in Week Three IV.A by the "Reliability Theory of Knowledge".

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