Descartes

 
How does Descartes try to extricate himself from the sceptical 
doubts that he has raised? Does he succeed? 
 
by Tom Nuttall 
 
[All page references and quotations from the Meditations are 
taken from the 1995 Everyman edition] 
 
In the Meditations, Descartes embarks upon what Bernard Williams 
has called the project of 'Pure Enquiry' to discover certain, 
indubitable foundations for knowledge. By subjecting  everything 
to doubt Descartes hoped to discover whatever was immune to it. 
In order to best understand how and why Descartes builds his 
epistemological system up from his foundations in the way that he 
does, it is helpful to gain an understanding of the intellectual 
background of the 17th century that provided the motivation for 
his work. 
 
We can discern three distinct influences on Descartes, three 
conflicting world-views that fought for prominence in his day. 
The first was what remained of the mediaeval scholastic 
philosophy, largely based on Aristotelian science and Christian 
theology. Descartes had been taught according to this outlook 
during his time at the Jesuit college La Flech_ and it had an 
important influence on his work, as we shall see later. The 
second was the scepticism that had made a sudden impact on the 
intellectual world, mainly as a reaction to the scholastic 
outlook. This scepticism was strongly influenced by the work of 
the Pyrrhonians as handed down from antiquity by Sextus 
Empiricus, which claimed that, as there is never a reason to 
believe p that is better than a reason not to believe p, we 
should forget about trying to discover the nature of reality and 
live by appearance alone. This attitude was best exemplified in 
the work of Michel de Montaigne, who mockingly dismissed the 
attempts of theologians and scientists to understand the nature 
of God and the universe respectively. Descartes felt the force of 
sceptical arguments and, while not being sceptically disposed 
himself, came to believe that scepticism towards knowledge was 
the best way to discover what is certain: by applying sceptical 
doubt to all our beliefs, we can discover which of them are 
indubitable, and thus form an adequate foundation for knowledge. 
The third world-view resulted largely from the work of the new 
scientists; Galileo, Copernicus, Bacon et al. Science had finally 
begun to assert itself and  shake off its dated Aristotelian 
prejudices. Coherent theories about the world and its place in 
the universe were being constructed and many of those who were 
aware of this work became very optimistic about the influence it 
could have. Descartes was a child of the scientific revolution, 
but felt that until sceptical concerns were dealt with, science 
would always have to contend with Montaigne and his cronies, 
standing on the sidelines and laughing at science's pretenses to 
knowledge. Descartes' project, then, was to use the tools of the 
sceptic to disprove the sceptical thesis by discovering certain 
knowledge that could subsequently be used as the foundation of a 
new science, in which knowledge about the external world was as 
certain as knowledge about mathematics. It was also to hammer the 
last nail into the coffin of scholasticism, but also, arguably, 
to show that God still had a vital r_le to play in the discovery 
of knowledge. 
 
Meditation One describes Descartes' method of doubt. By its 
conclusion, Descartes has seemingly subjected all of his beliefs 
to the strongest and most hyberbolic of doubts. He invokes the 
nightmarish notion of an all-powerful, malign demon who could be 
deceiving him in the realm of sensory experience, in his very 
understanding of matter and even in the simplest cases of 
mathematical or logical truths. The doubts may be obscure, but 
this is the strength of the method - the weakness of criteria for 
what makes a doubt reasonable means that almost anything can 
count as a doubt, and therefore whatever withstands doubt must be 
something epistemologically formidable. 
 
In Meditation Two, Descartes hits upon the indubitable principle 
he has been seeking. He exists, at least when he thinks he 
exists. The cogito (Descartes' proof of his own existence) has 
been the source of a great deal of discussion ever since 
Descartes first formulated it in the 1637  Discourse on Method, 
and, I believe, a great deal of misinterpretation (quite possibly 
as a result of Descartes' repeated contradictions of his own 
position in subsequent writings). Many commentators have fallen 
prey to the tempting interpretation of the cogito as either 
syllogism or enthymeme. This view holds that Descartes asserts 
that he is thinking, that he believes it axiomatic that 'whatever 
thinks must exist' and therefore that he logically concludes that 
he exists. This view, it seems to me, is wrong.  It should be 
stated on no occasion, in the Meditations, does Descartes write 
'I am thinking, therefore I am', nor anything directly 
equivalent. Rather, he says:  
 
      "Doubtless, then, that I existand, let him deceive me as 
he may, he can never bring it about that I am nothing, so long as 
I shall be conscious that I am something. So that it must, in 
fine, be maintained, all things being maturely and carefully 
considered, that this proposition I am, I exist, is necessarily 
true each time it is expressed by me or conceived in my mind." 
(p. 80). 
 
The point here is that it is impossible to doubt the truth of the 
proposition 'I exist' when one utters it. It is an indubitable 
proposition, and one that will necessarily be presupposed in 
every attack of the sceptic. Descartes is not yet entitled to use 
syllogisms as the possibility of the malign demon is still very 
much alive. As an aside, Descartes himself denies that the cogito 
is a syllogism, although it should be mentioned that in some of 
the Replies to Objections he seems to assert that it is in  fact 
a syllogism. Finally, in the Regulae ad directionem ingenii, 
Descartes denies the usefulness of syllogisms as a means to 
knowledge.  
 
I believe that, given Descartes' project, it is fair to grant him 
that the cogito deserves the status he bestows upon it. For can 
there be anything more certain than something that is so forceful 
and so powerful that every time it is presented to our mind we 
are forced to assent to it? 
 
What Descartes did here was to jiggle about the way philosophy 
normally approaches the construction of knowledge structures. By 
starting with self-knowledge, he elevates the subjective above 
the objective and forces his epistemology to rest upon the 
knowledge he has of his own self (and inadvertently sets the tone 
for the next 300 years of philosophy). This leaves him with a 
problem. He can know his own existence, that he is a thinking 
thing and the contents of his consciousness, but how can any of 
this ever lead to any knowledge of anything outside of himself? 
 
The answer is that, by itself, it can't. Descartes, in the third 
Meditation, attempts to prove the existence of God, defined as a 
being with all perfections. This proof is to be derived from his 
idea of a God, defined as a being with all perfections. So far, 
so good - Descartes examines the contents of his consciousness 
and discovers within it this idea, and we can allow him this. At 
this point, however, he introduces a whole series of scholastic 
principles concerning different modes of causation and reality 
without proper justification:  
 
"For, without doubt, those [ideas considered as images, as 
opposed to modes of consciousness] that represent substances are 
something more, and contain in  themselves, so to speak, more 
objective reality, that is, participate by representation in 
higher degrees of being or perfection than those that represent 
only modes or accidents; and again the idea by which I conceive a 
Godhas certainly in it more objective reality than those ideas 
by which finite substances are represented. 
     Now it is manifest by the natural light that there must be 
at least as much reality in the efficient and total cause as in 
its effect; for whence can the effect draw its reality if not 
from its cause? And how could the cause communicate to it this 
reality unless it  possessed it in itself?" 
 
Whence do these principles draw their indubitability? Even if we 
grant that it is contrary to natural reason that an effect can 
have greater 'reality' than its cause, that the concepts of modes 
and substances are coherent with Descartes' method, let alone  
possess the properties that he ascribes to them, then surely we 
can still bring the malign demon into play? Is it not possible 
that this all- powerful demon could bring it about that Descartes 
has a notion of a being with all possible perfections that he 
calls God? No, says Descartes, because the notion (representing 
something perfect) would then have more objective reality than 
the demon (as something evil and thus imperfect) has formal 
reality, and 'it is manifest by the natural light' that this is 
not possible. But why not? Maybe the demon has just made it seem 
impossible, and it seems that Descartes has no answer to this. 
 
Further problems remain. Cosmological arguments for God invoking 
the notion of causation have always had to contend with the 
problem of the cause of God. For if all events (or ideas) are 
caused ultimately by God, then what about God Himself? Why should 
He be exempt from this rule? The standard response to this is to 
claim that God, being omnipotent, causes Himself. One of the 
chief perfections that Descartes attributes to God is that of 
'self-existence', that is, that His existence depends on nothing 
else but itself. But if we examine this idea, it seems a little 
confused. If God is the efficient cause of God then we are forced 
to ask how something that does not yet exist can cause anything. 
If God is the formal cause of God, i.e. it is part of the 
intrinsic nature of God that he exists - which seems more likely 
- then it seems that we have merely a reformulation of the 
ontological argument for God's existence from Meditation 5. 
 
It seems that Descartes may have anticipated the wealth of 
criticism that the causal proof of God would inspire, and so, 
after explaining how human error and a benevolent, non-deceiving 
God are compatible in Meditation Four,  he produced in Meditation 
Five a version of the mediaeval ontological argument for God's 
existence. Unlike the causal argument, the ontological argument 
doesn't involve the covert import of any new principles. It 
simply purports to show that, from an analysis of his own idea of 
God, Descartes can show that He necessarily exists. The reasoning 
goes like this: 
 
I have ideas of things which have true and immutable natures. If 
I perceive clearly and distinctly that a property belongs to an 
idea's true and immutable nature, then it does actually belong to 
that nature. I perceive clearly and distinctly that God's true 
and  mmutable nature is that of a being with all perfections. 
Further, I perceive clearly and distinctly that existence is a 
perfection and non-existence a non- perfection. Thus existence 
belongs to God's true and immutable nature. God exists. 
 
One of the interesting things about this argument is that, at 
first sight, it does not seem to depend in any way upon anything 
that has been proved hitherto. It is an application of pure 
logic, an analysis of what we mean when we say 'God' and a 
inference from that  analysis. Descartes explicitly says that an 
idea's true and immutable nature does not in any way depend upon 
his thinking it, and thus upon his existence. Once he has 
perceived clearly and distinctly that an idea's true and 
immutable nature consists in such-and-such, that is the case 
whether or not he thinks it is, or even if he exists or not. 
Descartes in fact recognises the primacy of the ontological 
argument: "although all the conclusions of the preceding 
Meditations were false, the existence of God would pass  
with me for a truth at least as certain as I ever judged any 
truth of mathematics to be." If this is true, which it seems to 
be, then this argument is only as trustworthy as the faculties 
which enabled us to construct it, which are the same faculties 
that enable us to know mathematical truths, and so it seems 
worthwhile to ask how, under Descartes' theory, we come to know 
mathematical truths. Descartes claims we perceive them clearly 
and distinctly. How do we know that what we perceive clearly and 
distinctly is true? Because God, being perfect, is no deceiver, 
and would not let it be the case that we could ever perceive 
something clearly and distinctly without it being the case. It 
seems then, that this proof of God, relying on the veracity of 
clear and distinct ideas, relies on the certain knowledge that a 
non-deceiving God exists. We have another proof of God, the 
causal proof as described in Meditation three. But apart from the 
patent futility of using one proof of p to construct another 
proof of p, on examining the causal proof of God further, we find 
that it, too, relies upon a methodology that can only be relied 
upon if the divine guarantee is present, for if this guarantee is 
not present, then, as I mentioned above, how can we be sure that 
the all-powerful demon is not exercising his malignant influence? 
 
This, of course, is the infamous Cartesian circle, first 
identified by Arnauld in the Fourth Objections and discussed ever 
since. Many philosophers have tried to get Descartes off the hook 
in various ways, some by denying that there is a circle and some 
by admitting the circularity but denying its significance. I will 
here briefly evaluate a few of their arguments.  
 
Some commentators have taken a passage from Descartes' reply to 
the Second set of Objections (Mersenne's) to indicate that 
Descartes is only actually interested in the psychological 
significance of fundamental truths. The passage is as follows: 
 
"If a conviction is so firm that that it is impossible for us 
ever to have any reason for doubting what we are convinced of, 
then there are no further questions for us to ask; we have 
everything we could reasonably want." 
 
Under my interpretation,  this is what it is about the cogito 
that makes it so important for Descartes, so we cannot have any 
argument with the principle expressed by him in the above 
passage. But can it help break the circle? When we clearly and 
distinctly perceive something, Descartes says, fairly I think, 
that this perception compels our assent, that we cannot but 
believe it. God's r_le in the system, to these commentators, is 
as a guarantor of our memory regarding clarity and distinctness. 
In other words, once we have proved God's existence, we can 
happily know that any memory we have of a clear and distinct idea 
regarding x is true i.e. that we really did have a clear and 
distinct idea of x. But this does not seem satisfactory, as we 
still do not have a divine guarantee for the reasoning that leads 
us from the clear and distinct notions we originally have about 
God to the proof of His existence. We can give assent to the 
clear and distinct notions we have originally; in fact, we are 
compelled to give this assent when the notions are presented to 
our mind, but the logical steps we take from these ideas to the 
final proof is still subject to the evil demon because God is not 
yet proven. Furthermore, because these steps are needed, the 
memory of the original clear and distinct ideas are themselves 
subject to doubt because God is not yet proven. It seems that the 
only way either of the proofs of God could be accepted would be 
if we had an original clear and distinct perception of God 
directly presented to our mind (qualitatively similar to the 
cogito). But this in itself would make any future proofs 
redundant. Interestingly, this sounds quite similar to a divine 
revelation. 
 
Harry Frankfurt, in his book 'Demons, Dreamers and Madmen', has 
argued that what Descartes is actually looking for is a coherent, 
indubitable set of beliefs about the universe. Whether they are 
'true' or not is irrelevant. Perfect certainty is totally 
compatible with absolute falsity. Our certainty may not coincide 
precisely with 'God's' truth, but should this matter?: 
 
"Reasoncan give us certainty. It can serve to establish beliefs 
in which there is no risk of betrayal. This certainty is all we 
need and all we demand. Perhaps our certainties do not coincide 
with God's truthBut this divine or absolute truth, since it is 
outside the range of our faculties and cannot undermine our 
certainties, need be of no concern to us." (Frankfurt, p 184) 
 
This is almost a Kantian approach to knowledge, where we as 
humans only concern ourselves with the phenomena of objects as 
they present themselves to us, not with the objects in 
themselves. Can we ascribe this view to Descartes? It's tempting, 
given what we have said above regarding the prime importance of 
indubitability, but it would seem that a God presenting ideas to 
us in a form which doesn't correspond to reality, and then giving 
us a strong disposition to believe that they do correspond to 
reality would be a deceiving God and contrary to Descartes' 
notion of Him. Thus the belief set would not be coherent. 
Perhaps, as we do not have clear and distinct ideas of the bodies 
we perceive, and as the divine guarantee only extends as far as 
clear and distinct  ideas, we are being too hasty in judging that 
reality is how it appears to be and if we stopped to meditate 
further we would see that reality is actually like something 
else. But aside from  the fact that this seems unlikely, 
Descartes never seemed to envisage the possibility. 
 
So much for the Cartesian circle. Where does this leave the 
ontological argument, which we had only just begun to discuss? 
Aside from the methodological difficulties, there do seem to two 
further problems with it. The first has been noted by almost 
every student of Descartes over the years - that of the 
description of existence as a property. Put briefly, this 
objection states that existence is not a property like 'red' or 
'hairy' or 'three-sided' that can be applied to a subject, and 
thus it makes no sense to say that existence is part of 
something's essence. If we assert that x is y, we are already 
asserting the existence of x as soon as we mention it, prior to 
any application of a predicate. from the beginning. In 
other words, to say 'x exists' is to utter a tautology and to say 
that 'x doesn't exist' is  to contradict oneself. So how can 
sentences of the form 'x doesn't exist' make sense? one may well 
ask. It is because these sentences are shorthand for 'the idea  I 
have of x has no corresponding reality' and it was to solve 
problems like this that Bertrand Russell constructed his theory 
of descriptions. To add existence to an idea doesn't just make it 
an idea with a new property, it changes it from an idea into an 
existent entity. 
 
Finally, if Descartes is right, there seems no reason why we 
cannot construct any other  idea whose essence includes 
existence. For instance, if I conjure up the idea of an existent 
purple building that resembles the Taj Mahal', then it is the 
true and immutable nature of this idea that it is a building, 
that this building  resembles the Taj Mahal, that the building is 
purple, and that it exists. But no such building does exist, as 
far as I am aware, and if it did exist, its existence would not 
be necessary, but contingent. This in itself is enough, I think, 
to show that the ontological argument is false.  
 
Once we have destroyed Descartes' proofs of the existence of God, 
the edifice of  knowledge necessarily comes tumbling down with 
them, as we find that almost everything Descartes believes in is 
dependent on God's nature as a non-deceiver: 
 
"I remarkthat the certitude of all other truths is so absolutely 
dependent on it, that without this knowledge it is impossible 
ever to know anything perfectly." (p.115)  
 
The only possible exceptions are those assent-compelling beliefs 
such as the cogito.  Even these,  however, are doubtful when we 
are not thinking about them, and the above passage does give 
weight to Edwin Curley's argument that: 
 
"Descartes would hold that the proposition "I exist" is fully 
certain only if the rest of the argument of the Meditations goes 
through. We must buy all or nothing."  
 
This is not the end of the story, though. As far as Descartes is 
concerned, by the end of Meditation Five, he has produced two 
powerful proofs of God, has a clear and distinct notion of his 
own self, has a criterion for truth, knows how to avoid error and 
is  beginning to form ideas regarding our knowledge of corporeal 
bodies.. And so it remains only to explain why we are fully 
justified in believing in corporeal bodies, and also to draw the 
ideas of Meditation Two regarding self-knowledge to their full 
conclusion.  
 
Regarding the nature of corporeal bodies and our knowledge of 
them, it seems to me that, given his premises, the conclusions 
Descartes draws in Meditation Six are generally the correct ones. 
He again invokes the causal to argue that the ideas of bodies we 
have within our minds must be caused by something with at least 
as much formal reality as the ideas have objective reality. We 
could theoretically be producing these ideas, but Descartes 
dismisses this possibility for two reasons - firstly, that the 
idea of corporeality does not presuppose thought and secondly 
that our will seems to have no effect on what we perceive or 
don't perceive. (This second argument seems to me to ignore 
dreaming, in which what we perceive derives from us but is 
independent of our will). The ideas, then, could come from God, 
or from another being superior to us but inferior to God. But 
this, too, is impossible, argues Descartes, as if it were the 
case that God produces the ideas of bodies in us, then the very 
strong inclination we have towards believing that the idea-
producing bodies resemble the ideas we have would be false and 
thus God would be  allowing us to be deceived which is not 
permissible. The same would apply if any other being were 
producing these ideas. Thus, concludes Descartes, it is most 
likely that our ideas of corporeal bodies are actually caused by 
bodies resembling those ideas. We cannot be certain, however, as 
we cannot claim to have clear and distinct notions of everything 
we perceive. We can, however, claim certainty with regard to 
those properties of bodies which we do know with clarity and 
distinction; namely, size, figure (shape), position, motion, 
substance, duration and number (not all of these assertions are 
justified). Obviously we cannot claim that we know these 
properties for specific bodies with clarity and distinction, for 
to do so would leave open the  uestion of why it is that 
astronomy and the senses attribute different sizes to stars. What  
Descartes means is that we can be sure that these primary 
qualities exist in bodies in the same way that they do in our 
ideas of bodies. This cannot be claimed for qualities such as 
heat, colour, taste and smell, of which our ideas are so confused 
and vague that we must always reserve judgement. (This conclusion 
is actually quite similar to the one John Locke drew fifty years 
later in his Essay Concerning Human Understanding.) 
 
I think we can grant this reasoning, with the caveat regarding 
dreaming that I noted above, and of course the other unproved 
reasonings that Descartes exhumes here, such as the causal 
principle. Furthermore, it seems to be further proof that 
Descartes does believe we can get to know objects in themselves 
to a certain extent. 
 
Finally, I turn to Descartes' argument for the distinction of 
mind and body. Descartes believes he has shown the mind to be 
better known than the body in Meditation Two. In Meditation Six 
he goes on to claim that, as he knows his mind and knows clearly 
and distinctly that its essence consists purely of thought, and 
that bodies' essences consist purely of extension, that he can 
conceive of his mind and body as existing separately. By the 
power of God, anything that can be clearly and distinctly 
conceived of as existing separately from something else can be 
created as existing separately. At this point, Descartes makes 
the apparent logical leap to claiming that the mind and body have 
been created separately, without justification. Most commentators 
agree that this is not justified, and further, that just because 
I can conceive of my mind existing independently of my body it 
does not necessarily follow that it does so. In defence of 
Descartes, Saul Kripke has suggested that Descartes may have 
anticipated a modern strand of modal logic that holds that if 
x=y, then L (x=y). In other words, if x is identical to y then it 
is necessarily identical to it. From this it follows that if it 
is logically possible that x and y have different properties then 
they are distinct. In this instance, that means that because I 
can clearly and distinctly conceive of my mind and body as 
existing separately, then they are distinct. The argument, like 
much modern work on identity, is too technical and involved to 
explore here in much depth. But suffice to say that we can 
clearly and distinctly conceive of Dr Jekyll and Mr. Hyde as 
being distinct and yet they are identical, necessarily so under 
Kripke's theory. It is doubtful that Kripke can come to 
Descartes' aid here and Descartes needs further argument to prove 
that the mind and the body are distinct.  
 
And so we finish our discussion of Descartes' attempts to 
extricate himself from the sceptical doubts he has set up for 
himself. As mentioned previously, the ultimate conclusion to draw 
regarding the success of the enterprise that Descartes set for 
himself must be that he failed. When the whole epistemological 
structure is so heavily dependent on one piece of knowledge - in 
this case the knowledge that God exists - then a denial of that 
knowledge destroys the whole structure. All that we can really 
grant Descartes - and this is certainly contentious - is that he 
can rightly claim that when a clear and distinct idea presents 
itself to his mind, he cannot but give his assent to this idea, 
and furthermore, that while this assent is being granted, the 
clear and distinct idea can be justly used as a foundation for 
knowledge. The most this gets us - and this is not a little - is 
the knowledge of our own existence each time we assert it. But 
Descartes' project should not be judged by us as a failure - the 
fact that he addressed topics of great and lasting interest, and 
provided us with a method we can both understand and utilise 
fruitfully, speaks for itself.  
 
Bibliography 
 
1. Descartes, Ren_ A Discourse on Method, Meditations and 
Principles of Philosophy  trans. John Veitch. The Everyman's 
Library, 1995.  

Descartes, Ren_ The Philosophical Writings of Descartes volume I 
and II ed. and trans. John Cottingham, R. Stoothoff and D. 
Murdoch. Cambridge, 1985. 

Frankfurt, Harry Demons, Dreamers and Madmen. Bobbs-Merrill, 
1970.  

Curley, Edwin Descartes Against the Skeptics. Oxford, 1978. 
Vesey, Godfrey Descartes: Father of Modern Philosophy. Open 
University Press, 1971. 

Sorrell, Tom  Descartes: Reason and Experience. Open University 
Press, 1982. 

The Oxford Companion to Philosophy ed. Ted Honderich. Oxford 
University Press, 1985. 

Cottingham, John Descartes. Oxford, 1986. Williams, Bernard 
Descartes: The Project of Pure Enquiry. Harmondsworth, 1978. 

Russell, Bertrand The History of Western Philosophy. George Allen 
and Unwin, 1961. 11. Kripke, Saul Naming and Necessity. Oxford 
1980. 
 
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