PHL 323
Instructor: Dr. Bob Zunjic



Meditations On First Philosophy

An Outline

By their epistemological turn and foundational inspiration, the Meditations are rightly considered to be the seminal work of the entire rationalist strain of Modern Philosophy. Rationalist, but not, as may be expected, overly objectivist. While aspiring to attain absolute certainty as objective and universal foundations of knowledge Descartes proceeds in a very surprising manner - by introspectively reviewing the contents of his own mind.
I examines all possible reasons for doubt (both natural and supernatural) in order to make sure that the grounds for knowledge have been properly tested. This approach requires that what counts as knowledge can withstand any kind of skeptical attack and scrutiny. In keeping with this method Descartes constantly raises the extent and the intensity of doubt. Instead of simply presenting the definite results of his examination he engages the reader in the whole meditating process that is unfolding, as it were, before our eyes.
A trilingual HTML edition of the Meditations is available at:

Meditation One

Concerning Things That Can Be Doubted

Descartes does not start his meditations with some first certainties, as one would expect, but with those things that are uncertain, or better to say those that are dubitable. He wants to attain the aspired certainties (if there are any) by going through the readily available uncertainties of our beliefs.


Question: What are the "things that can be doubted"? 
Answer: Opinions, Beliefs, Assumptions. In brief, everything that is not known with certainty. 

Supposition: One cannot at the same time know something and doubt it. 

Fundamental Opposition: 

Doubt Certainty
Opinion Knowledge
Volatility Firmness
Changeability Solidity

Certainty: In order to vindicate our claims to knowledge we need to demonstrate that we are certain in what we deem to know. But certainty is not given. It must be attained and based on indubitable reasons. Thus we need to find absolutely convincing assurances that we are not mistaken.

Beginning: The goal of finding absolutely certain knowledge could be achieved only by going back to the very beginnings of our mental experience and by reflecting upon the foundations of human experience. "I would have to start again from the very beginning." The beginning is very personal.

Admission: Consequently, Descartes starts with a summary of his own life story: he recounts how he acquired his convictions and how he became aware that they lack certainty. "There is no novelty to me in the reflection that, from my earliest years, I have accepted many false opinions as true, and that what I have concluded from such badly assured premises could not but be highly doubtful and uncertain."

Time: The phrase "from my earliest years" seems to be pointing to the time when Descartes was still studying at the Jesuit College of La Fleche (1606-1615). Even though he fared exceedingly well in the school, with the exception of mathematics, he was not convinced that the knowledge provided by the sciences and other disciplines was properly founded. It is, however, pretty unlikely that already at that time he was able to articulate his intellectual dissatisfaction and develop a well rounded project of epistemological renovation. In fact, Descartes says that he realized how badly secured are his opinions only several years before the moment of undertaking the meditations (aliquot annos = Il y a déjà quelque temps).
The first vague ideas on the "badly assured premises" may have occurred in 1619, when Descartes was "detained in lodging" in the small town of Neuburg-on-Danube. He "stayed (there) all day shut up alone in a stove-heated room, where (he) was completely free to commune with (himself) about (his own) thoughts". That situation, closely resembling the setting depicted here in the Meditations, may have generated the strategy suggested below.

Realization: "I have realized that if I wished to have any firm and constant knowledge in the sciences, I would have to undertake, once and for all, to set aside all the opinions which I had previously accepted among my beliefs". In the following paragraph "setting aside" turns into a more radical "destruction". However, only in 1628 Descartes clearly formulated the plan of starting anew from much better secured premises. It took him another ten years though to embark seriously on the project. "But this enterprise appeared to me to be of very great magnitude, and so I waited until I had attained an age so mature that I could not hope for a later time when I would be more fitted to execute the project..."

Maturity: Before he was 45, Descartes obviously did not feel intellectually and otherwise ready to carry out his contrivance. In the winter of 1639, however, he decided it was time to grapple with the problem of his uncertain convictions, not just to brood over the idea. Consequently, if we can believe his own account, he withdrew from the public to execute his plan of going through his beliefs and opinions:
"Now, however, I have delayed so long that henceforward I should be afraid that I was committing a fault if, in continuing to deliberate, I expanded time which should be devoted to action."
"The present is opportune for my design; I have freed my mind of all kinds of cares; I feel myself, fortunately, disturbed by no passions; and I have found a serene retreat in peaceful solitude." (The Meditation probably took place somewhere in the vicinity of Utrecht.)

Ego: The most frequent word in these opening statements is the "I" - a strong indication of the decisive shift in Descartes' focus from the study of the external world (the "book of nature") toward self-examination (the study of Self).
It is no less indicative, however, that Descartes does not elaborate the nature of this "I" beyond stating later on that it is mental. The vacuousness of the "I" will have proved very instrumental in reducing this Self to thinking and ultimately in creating a gap between the mind and the body.

Mode: Personal Story; Philosophical Journal.
Narrator: The Author, The Meditating Subject ("I")
Topic: Intellectual Crisis; Previous Knowledge Badly Assured.
Plot: Radical Beginning; Staging a Situation of Philosophical Renovation.
Objective: Certainty; To Establish Firm and Lasting Foundations of Knowledge.
Means: Methodical Doubt; Withhold Assent to All Dubitable Claims
Motive: Trust; To Gain Over the Reader (Novice) to Meditate Along.

Philosophical Lexicon 
Meditation = a continual or extended thought, usually based on spiritual introspection and aimed at illumination. By taking over this old form from the religious tradition of spiritual exercises and applying it to epistemological issues Descartes created a new genre: philosophical meditation. The ascetic rejection of the flesh is here transformed into a more modest cognitive detachment from the senses. Instead of religious salvation the philosopher seeks to accomplish an "epistemological salvation" in view of the threatening skeptical encroaches. 

First Philosophy = the part of philosophy dealing with the first principles that lay grounds for everything else (reality or knowledge); in Aristotle, it is metaphysics (ontology) that studies the principles of the existing world; in Descartes, it is epistemology seeking the firm and permanent principles of human knowledge. This turn (known as epistemological) moves from the ordo essendi (order of being) to the ordo cognoscendi (order of knowledge, order of reasons). 

Epistemology = theory of knowledge; the branch of philosophy that studies the possibility, the conditions and the nature of knowledge. 


Both the Meditation-format, which was purposely chosen to provide a convincing framework for an introduction to philosophizing, as well as the project of First Philosophy, being itself a primary striving to attain the truth, had a preparatory function with regard to the ambition of securing the ground for the real knowledge of life experience and the sciences. However, there is one big difference. Instead of immediately kicking off a new construction of knowledge out of a preconceived plan (as was common in the tradition of previous philosophy) Descartes set out to first destroy the existing structure in order to prepare the ground for a new (better) edifice. In this way he wanted to avoid previous mistakes and blunders and so attain absolute certainty that the new construction is sound. Only after the ground has been cleared the new foundations could be laid down with confidence that the newly errected edifice will be solid and lasting.
Demolition In order to be able to accomplish this goal of finding a reliable foundation of knowledge the meditating subject needs to apply a very rigorous procedure of destroying opinions: "I will therefore make a serious and unimpeded effort to destroy generally all my former opinions." The demolishing ball for the existing structure of knowledge will be doubt. It has the advantage of both being destructive and easy to handle. The effect of doubting is justly compared to a demolition of a sumptuous but dilapidated edifice of knowledge.
Dubitandum est: The inspiring idea of Descartes' procedure is de omnibus dubitandum est (= everything is to be doubted).  At first this sounds very skeptical, almost paranoid.
The corrosive doubt that has to be exercised must be both universal (no exceptions) and radical (ruthless and far-reaching) but, unlike paranoid doubt, it is methodical (systematic).
Methodical Consistent
Universal Comprehensive
Radical Profound
Preemptive Skepticism: In many respects Descartes' tactic is truly skeptical. He strenuously seeks possible grounds for doubt in order to identify the propositions that are suspicious and dubious and thus have to be discarded. Resorting to excessive doubt may create the impression Descartes strives to undermine the very possibility of human knowledge. But he is not a skeptic who wants to dismiss everything we believe to know. He has a positive aim - certainty as the hallmark of the believability of our truths.  
Positive Goal While his tactic may look like skeptical Descartes' strategy is the very opposite of skepticism. He feverishly examines a series of all possible cognitive levels in hope that by sifting through their claims he will finally reach not the negation of knowledge but the realm of indubitable knowledge. This requires a proper understanding of his pledge to demolish all his previous opinions. The destruction is conducted for the sake of replacing opinions with knowledge not in order to abdicate from knowledge. Destruction does not mean proving that everything is false nor does it amount to the refutation of every claim to knowledge.
Negative Criterion: To be sure Descartes does not want to start dogmatically by professing things he cannot prove. However, he realizes that if he cannot prove anything beyond any doubt, he can easily disprove everything simply based on the very possibility of doubt (if it exists). This procedure comes very handy because it is much easier and safer to doubt than to assert and prove something. Thus Descartes' destruction means more rejecting temporarily everything that could be doubted than proving that it belongs to the repository of falsities. "It will be enough to make me reject them all if I can find in each some ground for doubt." This gives a powerful tool in search for knowledge that should not be compromised. That's the main reason why Descartes does not make any difference between incomplete certainty and obvious falsity. On the contrary, he reverses the usual burden of proof for the purposes of his epistemology: for the verdict he does not seek a reasonable doubt let alone the beyond reasonable doubt clause - a slightest shred of suspicion suffices to condemn the opinion and to reject it. 
Beyond reasonable doubt 95% to be condemned
Reasonable doubt 51% to be condemned
Slightest doubt 0,000... ...1 to be condemned
  Note: The rejection, however, is rather a suspension than a total disbelief. The existing doubts do not suffice to conclusively prove the falsity of our opinions - only to shatter our trust in them. This makes the doubt provisional and tentative, though progressive.
Method of Doubt
Character of Doubt
Provisional Temporary Suspension.
Tentative Assuming Falsity.
Progressive Going through Stages.
Specifications: How to carry out this doubt without omitting anything in the process? This looks like a daunting, impossible task. Fortunately, Descartes does not need to do any of the following two things:
(a) To demonstrate that his opinions are "all false";
(b) To "examine each one (opinion) in particular". 
First of all, the number of possible statements is virtually unlimited and nobody can survey all opinions. It would be practically impossible to complete the inspection of all beliefs.
Second, even if this were possible, it is questionable whether Descartes would be able to prove that all of these opinions are really false.
The problem at this stage is not that Descartes cannot inspect each and every opinion, but that he cannot find out exactly which opinions are to be dismissed and separated from possibly true opinions. He lacks an indubitable starting point and a positive criterion of demarcation between truth and falsity that would decide beyond any doubt which propositions are true or false.
Selective Inspection: If all opinions cannot be inspected, the examination focuses on the existing foundations (sources of knowledge). Thus only those principles which lay ground for our current beliefs are being examined, not all derived opinions. In this way all beliefs could be tested at once insofar as they are directly grounded on these principles (the structure of knowledge depends on its foundations). Therefore the destruction of the foundations will entail the collapse of the condemned structure.
Beginning Hence Descartes does not start the investigation by claiming that human mind is very weak and obscure. If that were the case his own undertaking would be futile. Even less does he dismiss all human knowledge as entirely unreliable. In that case his search for certainty would be self-contradictory.
The only reasonable strategy is to examine human knowledge at their very sources: the senses and reason. While performing the examination of the two main cognitive sources Descartes will abstain from believing in any of his beliefs derived from them.
Senses Descartes first focuses on the senses: "Everything which I have thus far accepted as entirely true and assured has been acquired from the senses or by means of the senses (= hearsay)."
This statement points to the following (implicit) thesis, which is in fact the target for the initial part of the doubting process:
The First Principle To Be Examined:
All my reliable knowledge comes from the senses.

Preliminary Question: Granting that sense perception is the source of our knowledge, does it provide any certainty? The ensuing critique of the senses does not purport to say that no sensory belief could be reliable, only that such beliefs could not be regarded certain if we have no reasons in their favor other than those obtained through custom and common sense.


Natural Doubt
  Descartes first examines logical (normal) reasons for doubting the reliability of the senses.
(I) Dubitation:  The Illusion Argument. Descartes first addresses the occasional deceptiveness of sensation. It is a common fact that the senses are sometimes deceptive, especially when we are confronted with "things that are barely perceptible and very far away" (mirages, optical and other illusions; cf. a "bent oar" in the pond). Therefore, it is prudent not to trust the senses.
(Sayings: "Fool  me once, shame on you, fool me twice, shame on me"; "Once a liar, always a liar.") 
Credence: Yes, the senses sometimes fail, but that is an exception to the rule. The senses do not deceive us invariably; if that were the case, we would not be able to identify moments of deception at all. The senses are not designed to operate under extremely unfavorable external conditions  (small and distant objects, those immersed in mist or water). However, the perception of "immediately present things" is reliable: "There are many other things which we cannot reasonably doubt, for example, that I am here, seated by the fire... How could I deny that these hands and this body are mine?"
Correction of the first principle:
The senses provide self-evident knowledge about immediate objects in good external conditions.
(II) Dubitation:  The Madness Argument.  The reliability of immediate sensory knowledge is compromised by the way how some people perceive themselves. Their senses are otherwise intact but they see themselves dressed in fancy robes when they are in fact in nude. This shows that we can deny self-evident things or assert those that plainly contradict reality. To falsify reality perceptually it suffices that our mental balance is deranged as is the case with those "lunatics (insensés) whose brain is so troubled and befogged by the black vapors of the bile that they continually affirm that they are kings while they are paupers, that they are clothed in gold and purple while they are naked..." Since all knowledge of our own body and our surrounding is dependent on sense perception and since perception of immediately present objects could lead astray, how can we in general trust our senses? After all, we could be really insane and thus defective perceivers.
Credence: The comparison with insane people is not appropriate because we are not following their example (in other words: we are not insane). How do we know that? By relying not only on sheer senses but on the good sense (sensus bonus = reason) as well. (This entails the second principle to be examined: sensus communis as another source of knowledge but Descartes does not name it yet.) The problem lies not with the senses - they are not defective in themselves although they suffer from the mental disorders in the interpretive neural centers. Insane people make use of the senses, but they do not correct the distortions supervining on their perceptions and self-perceptions by virtue of reason. They cannot because they have lost the power of reason. This is why they do not distinguish between madness and sanity (rationality). Fortunately, these people make up only a small portion of human kind and any conclusion based on their inability to report reliable self-perceptions cannot be justifiably stretched to include all humans. 
  Note: It is no accident that Descartes discards insanity without rest as totally opposed to knowledge whereas he is much more selective in dealing with sense illusions and dreams. The aforementioned distinction between insanity and reason is not only an epistemological one; it points to the birthplace of insanity as a social fact. As Michel Foucault has shown, never before the 17th century have insane people been systematically isolated and treated as socially deviant persons.
First principle corrected again:
The senses are reliable when we are qualified perceivers, that is to say - when internal conditions are satisfactory. 

(III) Dubitation:

The Dream Argument.  Extreme pathological conditions are not the only ones that nourish doubt about sensory knowledge. Dreams represent a non-pathological equivalent to madness, and one which is very common: while only a few individuals are totally insane we are all accustomed to sleep and we all have dreams. "I must remember that I am a man, and that consequently I am accustomed to sleep and in my dreams to imagine the same things lunatics imagine when awake..." Dreams show that even under non-defective mental conditions sensory knowledge could be deceptive. "How many times has it occurred that the quiet of the night made me dream of my usual habits: that I was here, clothed in a dressing gown and sitting by the fire, although I was in fact lying undressed in bed." Dreams are therefore a "hyperbolical exasperation" of insanity that makes a stronger case for doubt because they are so common and widely spread. One can even claim that insane people are never so wild in their perceptions as dreamers could be. Very often in dreams we experience "even less plausible" things than those reported by insane people.  As regular dreamers we are therefore even more disposed to sense things that undermine the trustworthiness of our senses. 

  Note: The above reasoning gives a strong support to those who criticize the interpretation of M. Foucault. For instance, J. Derrida contends that, for Descartes, insanity represents only "a particular case, by no means, the most serious one of sensory illusions". Insane people are not "sufficiently insane" to be invoked as ultimate rebuttal against sensory knowledge.
Credence: Disregard for reality in dreams does not amount to a sweeping case against the senses. Sleeping perceptions cannot compromise the good perceptions that possess much better quality than dreams. "What happens in sleep seems not at all as clear and distinct as all this" (= I am perceiving now). In addition to the obvious lack of clarity and distinctness, dreams do not allow acting "with design and deliberate intent". This gives us a tool to separate valid perceptions from those that are only dreamed. If the distinctness and clarity of perceptions are lower in dreams than in reality and if the content of dreams is involuntary (as opposed to our conscious acts), then we can draw a demarcation line between the two and trust only clear and distinct waking perceptions. And justifiably so.
Third correction:
The perceptions that are clear, distinct and amenable to deliberate control are reliable.
(IV) Dubitation: The Indiscernibility Argument.  Despite his personal experience with fateful dream Descartes did not believe in the so called "lucid dreams" that, according to the controversial testimony, allow deliberate control and produce clear and distinct images. Hence he did not invoke them as a counter-argument for further doubt. But he adduced a special subclass of dreams that closely resemble wake perceptions. Sometimes we have vivid dreams that are qualitatively just like waking perceptions. "But I am speaking as though I never recall having been misled, while asleep, by similar illusions. When I consider these matters carefully, I realize so clearly that there are no conclusive indications by which waking life can be distinguished from sleep that I am quite astonished, and my bewilderment is such that it is almost able to convince me that I am sleeping." 
Thus, at least in the case of very vivid dreams (and who has not experienced them?), it is virtually impossible to draw a clear demarcation line between being awake and being asleep. Now this presents a problem: If I cannot distinguish with certainty between my waking perceptions and vivid dreams, then my waking perceptions provide no reliable knowledge simply because I cannot be sure that they are not dreamed as well. 
  Note: Descartes only contends that the resemblance between his waking life and his dreams is quite sufficient to allow doubts about seemingly undeniable immediate perceptions. How to discern wake condition from dreaming is an old epistemological problem. For the difficulty compare the Riddle of Chuang Tsu: 'I fell asleep and started to dream I was a butterfly flying over the meadows. Upon awakening I don't know whether I am a man who was dreaming to be a butterfly, or a butterfly now dreaming to be an awakened man.' "The Matrix" movie offers another parallel: "You ever have that feeling where you're not sure if you are awake or still dreaming?"

Sometimes it is really difficult to distinguish between dreams and reality. But this difficulty does not prove that we are dreaming all the time and that there is nothing real to be conveyed by our senses. Dreams in themselves are not empty; they must have some content: people, animals, houses, trees, things of whatever kind. This content is based on our perceptions of reality or at least manifests the same regularity regardless of our ability to distinguish between dreams and waking perceptions. Even when dreams produce illusions they are like "painted images", i.e., representations  made in the likeness of real things (bodies, limbs, organs). "We must at least admit that these things which appear to us in sleep are like painted scenes and portraits which can only be formed in imitation of something real and true ..." The fact that both waking and dreaming perceptions display the same patterns and shapes suffices to claim that they preserve something that is reliable in our sensory perceptions.


Note: This answer does not refute the indiscernibility argument as such, only the claim that there is nothing reliable and real since only dreams exist. In the 6th Meditation Descartes will introduce memory as the distinguishing mark between sleep and wake: dreams are never linked by memory as the waking experiences are. Therefore it is not plausible to claim that we are in a state of perpetual dreaming. In that case no one would be able to speak sensibly about the distinction between reality and dreams. To be sure, the previous thought (about different levels of distinctness) might be a part of the dreaming process itself, but then the question of reliability will apply only to the reality of dreaming. (Although "The Matrix" movie suggests that regular life is just a dream, even within that condition it is possible to penetrate the veil of illusion and attain the knowledge of reality, truly by means of a pill.)

First principle corrected further:
At least some general things we perceive both in our dreams and while being awake are real and therefore their sensory reports are undeniable.
(V) Dubitation:

The Imagination Argument.  Those "general things" (representations of bodies, heads, arms, eyes, etc.) that make up our dreams could be just a product of our imagination. This argument is rather implicit than explicit, but it could be reconstructed from what Descartes says as proceeding in two steps: (a) and (b).
(a) The content of our dreams could be concocted the way artistic ingenuity works in fantastic (or surrealist) painting = by putting together in a strange manner otherwise really existing parts.
(b) The extravagant imagination of dreams could invent entirely new forms that have never been seen before (cubist or abstract) = in that case not even the parts of the bodies would persist throughout the process.
Thus imagination may create various combinations of pre-given parts, combinations which more or less resemble existing things, or it may go deeper and produce both new parts and entirely new shapes.

Credence: (a) Fantasies of dreams operate within certain limits: they must have some already existing constituents even when they do not possess direct real models. The analogy with painting points to some persisting parts and forms. "For in truth painters, even when they use the greatest ingenuity in attempting to portray sirens and satyrs in bizarre and extraordinary ways, nevertheless cannot give them wholly new shapes and natures, but only invent some particular mixture composed of parts of various animals." In other words, even when they produce nonexistent beings (sirens, satyrs), they make use of some real objects of the same general sort. Thus, "these types of things, namely eyes, head, hands, and the whole body, are not imaginary entities, but real and existent". 
(b) If imagination produces entirely novel things beyond a mere combination of already available and recognizable parts (which is possible), still it cannot invent their more simple components. These components are elements that make up all types of things, all objects and their constituents. Invention and imagination cannot create or abolish these elements. "And for the same reason, even if these types of things - namely, a body, eyes, head, hands, and other similar things - could be imaginary, nevertheless, we are bound to confess that there are some other still more simple and universal concepts [which are true and existent], from the mixture of which, neither more nor less than in the mixture of colors, all these images of things are formed in our minds, whether they are true or imaginary and fantastic." Hence, imagination in this case would be just a cubist painter who uses "more simple and universal concepts" to create or depict reality. These concepts "are true and existent" and they represent the ultimate residue of reality.
To escape the arbitrariness of dreams and imagination we need to look for more fundamental and general "natures" that permeate both wake and sleep perceptions: these are "simple and universal concepts".
  No matter whether we are awake or dreaming the objects we "see" must display these simple concepts and our reasoning must go by the rules of logic.
Rule: The certainty does not reside in the complex but in the simple and the universal.
Question: What are these "still more simple and universal concepts"?
Answer: They are the factors that explicate the corporeal nature of all entities (simple concepts), or state some undeniable truths of abstract nature (universal concepts).
Simples: (a) Simple concepts are twofold: 
(1) Those that are accidental and subjective (= secondary qualities), and 
(2) Those that objectively inhere to the entities (= primary qualities of bodies).
Secondary Qualities
Primary Qualities
Color Extension
Sound Shape
Taste Size
Odor Number
Touch Place

Each body can be analyzed into these "objective qualities". They mark the limits of all analysis and consequently cannot be broken down into further elements. They are at once the most simple and general components of reality: most "simple" because we cannot find more simpler components while retaining the integrity of objects (atomic structure goes below this level) and they are the most "general" because they inhere all corporeal objects.
Note: "Colors" are mentioned here in a very specific although misleading sense. In fantastic (mythological) painting they indicate the residual reality of the made up figures. Strictly speaking, "colors" do not really belong to the category of "objective" qualities. But they seem to possess a kind of "primitive inescapability" (Rorty), which makes them irrefutable as "sense-data" - not in the sense that I cannot be mistaken in my color-perceptions but in the sense that when I see a color then I really see a color. This "irrefutability" of my conscious reports rather than a kind of transcendental claim that every object must possess certain color may explain why Descartes lists colors along with the physical "simples". He is making an analogy between the colors in painting and physical simples. It should be noted, however, that in the second instance he calls the simples and the components as such the "true colors" from which the objects are fashioned. This confirms the interpretation that "colors" here in fact stand as a general name for the primary qualities.

Accuracy 1: The sciences that deal with these simple concepts ("treat only of very simple and general things") possess "some element of certainty", whereas "all the other sciences which follow from the considerations of composite entities are very dubious and uncertain". The reason for this is that the simple concepts are quantifiable and measurable while the level of accuracy drops with the increase of complexity (it includes secondary qualities as well).
A parallel with Ancient Philosophy: While Aristotle was claiming that the sciences relying on "fewer principles" are "more accurate", Descartes contends that those dealing with the more "simple" components and concepts are more "certain".
Certain Sciences
Uncertain Sciences
Arithmetic Physics
Geometry Astronomy
Universals: (b) Universal concepts are "common notions" which express some obvious truths whose validity is secured by their analytic form (mostly statements of Logic and Mathematics). 
These concepts are a priori  true regardless of external or internal conditions.
At this point Descartes comes very close to name reason another major source of our knowledge but, as in the madness argument, falls short of any explicit formulation.
Note: Analytic concepts include statements like these: "The part is less than the whole", "Two things equal to a third are equal to each other", etc. Throughout the Meditations Descartes uses such analytic concepts as a means of conclusive demonstration.
Accuracy 2: Another reason why the sciences dealing with more "general things" are more certain: Statements made in the language of Arithmetic or Geometry are absolutely undeniable ('two plus three equals five'; 'a square has four sides'), whereas those asserted by physics, astronomy or medicine could be called into doubt because they are dependent on sensory perception.
Vivid Dreams Congruence with real objects (General Things)
Creative Imagination Concatenation of pre-existing parts
Extravagant Imagination Simples and Universals
Reality How does this reasoning prove that the things we perceive exist and that our perceptions are accurate? Obviously this is not what the imagination argument proves. Descartes does not want to say that primary qualities and universal truths prove that what we "see" exists, that we are not dreaming, and especially not that what we perceive in dreams is really so. He only wants to say that if these things exist they must have these qualities as their boundaries and that they must appear in our dreams within these boundaries as well. His reasoning is more about the reliability of our knowledge than about the reality of objects.
Existential Indifference This necessity renders irrelevant the issue whether the perceived things exist or not, whether we are dreaming or not. The knowledge that is indifferent to the question of existence seems particularly apt for certainty regardless and beyond the divide of wake and dreaming perceptions.
"For whether I am awake or whether I am asleep, two and three together will always make the number five, and the square will never have more than four sides: and it does not seem possible that truths so clear and apparent can ever be suspected of any falsity or uncertainty." 
Conclusion: Since these "simples" are constitutive for everything real Descartes goes even further and regards them as the conditions both of existence and meaningful discourse. If primary qualities are negated, both the world of dreams and the physical world would cease to exist. If we negate analytic truths, nothing sensible could be said about anything.
First principle in final formulation:
If primary qualities persist even in dreams while analytic truths remain un-shattered under all conditions, then the statements reporting about primary qualities or those expressing analytic truths are no less reliable when we dream than when we are awake. 

We are, therefore, justified in assuming that there is a material world consisting of certain elements and organized logically/mathematically. We can be sure that the things we perceive possess primary qualities and that these qualities and their relations could be expressed in accordance with analytic truths.

Philosophical Lexicon

Primary Qualities: The qualities that are believed to be inherent characteristics of things and not dependent on observer's subjectivity like secondary qualities. The distinction was made already in Antiquity, but received a full elaboration only in Modern Philosophy (Locke).

Sensus Bonus: (Latin: the good, "healthy" sense), i.e., reason (in contrast to the five senses, which are not cognitively good as is reason); sensus bonus coincides with the common sense insofar as they both denote that which seems sensible (rational) to all people with non-defective abilities; however, this coincidence is only partial, because sensus communis in Descartes often denotes simply what is common both to the body and the soul. Descartes placed the seat of reason in the cerebellum (the pineal gland).

Analytic Statement: (from the Greek analytikos = pertaining to taking apart), the statement true by definition, necessarily true because of the relationship between its concepts, or because the meaning of its predicate is already contained in the meaning of the subject. The truth of an analytic proposition is known in advance (a priori) and needs no empirical verification (for instance, "a triangle is a plane figure with three sides"). One needs only to understand what it says. Opposite to synthetic, a posteriori, empirical statements. 



Arguments I-V focus primarily on the question whether we can accurately tell when we are perceiving real things, not whether such things exist. The doubt which inspires these arguments is based on "natural reasons", that is to say the reasons that are derived from real circumstances and normal possibilities (assuming no supernatural intervention). Now the existence of the world is being challenged from the vantage point of "transcendent" considerations: Descartes asks what if something superhuman (God or a demon) hampers our cognition of the "simples". If God is an omnipotent being, then he could produce such a thorough deception that we cannot break through it. The possibility of a deceiving Deity is introduced to undermine the commonsense belief that all our impressions must be traceable back to the experience of the real world.

Metaphysical Doubt
  After examining natural reasons for doubt Descartes has to rule out those that are not so likely and yet possible, namely that there is a super-natural being powerful enough to cause deception. Due to this non-experiential hypothesis the initial natural suspicion turns into a profound metaphysical doubt.
(VI) Dubitation: The Good Deceiver Argument (Deus Deceptor). External conditions might be ideal, our cognitive organs non-defective, we ourselves waking and focusing on simple qualities and analytic truths, but God might be deceiving us anyway about the content of our perceptions and thoughts. (a) A powerful being like God "can do anything" (the omnipotent Creator). Hence he could make that our images do not correspond to anything real (Descartes assumes the validity of the representational theory of perception all along). "But how can I be sure but that he has brought it to pass that there is no earth, no sky, no extended bodies, no shape, no size, no place, and that nevertheless I have the impression of all these things...?"
(b) Perhaps God has created us so that we all the time hallucinate the entire physical world along with the logic of our calculations which urges us to believe that two plus three make five. "How can I be sure but that God has brought it about that I am always mistaken when I add two and three or count the sides of a square?"
If this is the case, one can be deceived both about the existence of "simple elements" and the validity of mathematical truths.
  Note: Why is mathematics rendered doubtful by the possibility that there is no external world and that God instills the illusion of an existing world into our minds? If there is no world, there are no elements and no universal truths expressing their relations. This argument does not invalidate the contention that mathematical propositions are analytically true - in dreams and hallucinations they could not be perceived otherwise but confusedly.
Credence: God is by definition "supremely good" and it is "repugnant to his goodness" to have made us so that we are always mistaken. "God did not wish me to be deceived in that fashion." In view of so many sensations, we cannot call into question the very existence of the external world as reported by our senses. The same applies to our rational reasoning (logic and mathematics). If it was contrary to God's goodness to allow a permanent deception, it would seem also to be inconsistent for him to permit even occasional deception. "It would seem also to be inconsistent for (God) to permit me to be (even) sometimes deceived." Or at least, he should not be involved in deception (Plato argues about this point in the second book of the Republic).
(VII) Dubitation:

The Factual Deception Argument. Deception occurs - "I cannot doubt that he does permit it" - therefore, it is not incompatible with God's goodness. God's goodness is perhaps incompatible with permanent deception, but since we are sometimes deceived, we do not know whether we should exempt our elementary beliefs in simple concepts and obvious truths from doubt or not. If deception happens sometimes, why not most of the time? We cannot make any assertion to the effect that God deceives only exceptionally or not at all. Simply, we do not know God's ways. Thus everything remains uncertain. 

  Note: Descartes was aware that some theologians would rather sacrifice the intelligibility of God's acts than limit his freedom in any respect (Objection VI).
Credence: Deception is a mark of weakness and, consequently, it contradicts omnipotence. If you insist that God nevertheless deceives us or allows deception, I "would prefer to deny the existence of so a powerful God, rather than to believe that everything is uncertain". If deception occurs although it is inconsistent with God's goodness, that means only one thing: it is not powerful God who deceives us either perpetually or occasionally but something less than God. We "have reached the state of being (we) now have" by virtue of some source less powerful than God (destiny, fate, chance, "a continual interplay of events"). Therefore we cannot either blame or credit God for actual or potential deceptions. God does not exist ("God is fictitious"). However, if there is no Deceiver-God , there is no externally caused systemic deception either. Therefore we need to pay attention only to our own mistakes.
  Note: Why Descartes as a faithful seriously entertains the possibility that God does not exist? Is this a contradiction? Descartes was convinced that it was absurd to claim that God necessarily sustains the truth and nonetheless reserves liberty to create deception. So he wanted in fact to exonerate God from deception. In addition, as a philosopher, he could not help taking seriously the atheist option as well. Why deception occurs sometimes is explained in the 4th Meditation.
(VIII) Dubitation:

The Imperfect Creator Argument. No matter whether our cognitive abilities have been created by fate, chance, interplay of events or in any other non-intelligent way, they could be defective. Moreover, if the origin of our mind is less powerful and good than God, we have more reasons to believe that we are mistaken in our perceptions and beliefs. This is a matter of probability and yet its principle is sound: the more perfect creator the better his chances are to create something perfect. If there is a likeness or a proportion between the creator and his products, and this seems to be a plausible belief, then a more intelligent and a more able designer could and should create more perfect beings. Accordingly, in disclaiming any participation of intelligence in the act of creation we are denying (or at least diminishing) the last hope for any epistemological security. So let us face the reality of that denial: we cannot be sure.

Perfect Creator Imperfect Creator
Intelligent Creator Non-intelligent Creator
More Intelligent Creatures Less intelligent Creatures
Less Susceptible to Deception More Susceptible to Deception



"To err and be deceived is a kind of imperfection."
Conclusion: Therefore only if we closely resemble a perfect creator can we be exempt from deception.
Premise: But we do not resemble a perfect creator if we were created by accident.
Premise: A degree of imperfection currently defines human nature.
Conclusion: Therefore we cannot claim that we are not being deceived.
  Note: A powerful and good God might have saved us from deception out of his mercy, whereas the anonymous forces of nature do not commiserate with us. But we have seen that deception occurs even under the assumption that God exists. Thus, either created by God or not, our mind remains subject to continual error and perpetual hallucinations (cf. the situation depicted in the brothers Wachowski's movie "The Matrix").
No Credential
"To this reasoning, certainly, I have nothing to reply."
I cannot trust my beliefs simply because I am an imperfect human being possibly created by very imperfect forces. Therefore I could be wrong just about anything.


The world is revealed to be real only insofar as it is disclosed to our experience, which might be deceptive.
Hyperbolical Doubt
  Descartes now introduces an entirely implausible hypothesis in order to sustain his doubt. He can stay on alert against possible deception only if he assumes that the threat of deception is total and thorough.
Skeptical Conclusion: Descartes was willing to accept the simple and universal concepts as the last residues of reliable knowledge if it were not for the possibility of a comprehensive deception caused either by a divine design or accidentally. Having been unable to rule out that possibility after examining both natural and supernatural reasons for doubt he found himself empty-handed:
"There is nothing in what I formerly believed to be true which I cannot somehow doubt." On the contrary, I should be on guard against everything that can creep into my mind.
Practical Conclusion: Given this negative result Descartes must embrace a very rigid methodical rule: Withhold Assent. "Thus I find that, in the future, I should withhold and suspend my judgment about these matters, and guard myself no less carefully from believing them than I should from believing what is manifestly false..." 
A Difficulty: Habit, Inertia. How to abide by this decision? The force of habit and a natural leniency ("laziness of mind") drag us back to the old customary beliefs and opinions which make themselves masters of our convictions. All the more so as some of them are "highly probable" while the required "epistemological regimen" is very austere and unappealing.
Note: The famous verses of Horace come to mind when reflecting on the power of habit: Cognosco meliora proboque, deteriora sequor. The knowledge about what is better does not necessarily determine the course of action if the will for it is missing.
Solution: General (Epidemic) Doubt. To withstand the habit of deferring to customary beliefs, one should make a willful effort in the opposite direction. "I would not do badly if I deliberately took the opposite position and deceived myself in pretending for some time that all these opinions are entirely false and imaginary." In this way (by "allowing to be deceived") I will counterbalance previous false opinions with my new self-deceptions in a kind of a safe stalemate.
Note: The astounding strategy of "allowing to be wrong " and even volunteering self-deception is contrived here for the first time but it reaches its pinnacle in the second Meditation. We encounter the same type of reasoning time and again in the Meditations. Since it is possible that I am mistaken I should assume that I am actually mistaken and consequently I'll keep doubting my perceptions as well as what seems to be evidently true.
Remedy: Hyperbolic Doubt. What was just a deliberate surmise needs now to be secured as the possibility of total deception. This deception would affect even the truths of mathematics precisely because it is so thorough and comprehensive. When deception reaches that point it is difficult to distinguish it from the truth and therefore it becomes even more dangerous: nobody would suspect it let alone allow for the possibility that mathematics could be wrong. But I cannot ascribe such a thorough and continued deception to a good and truthful God. To sustain continuously our vigilance against that possibility of being deceived (which could not be overdone), Descartes suggest to surmise that there is a certain "evil demon" (malin genie = malignant genius), who has bent all his efforts to deceiving us. This "evil demon" accumulates previous creationist and atheist doubts (cf. Credence VII) and transforms them into a formidable epistemological threat that suppresses any self-complacency. The only way to counter his enormous power is not to accept anything and not to trust any opinion even if it appears to be an obvious truth.
Note: The hypothesis of an "epistemological Satan" should help us both to overcome dogmatic inclinations of common sense and refresh our waning doubts regarding all judgments based on the senses. This self-induced fiction makes it psychologically acceptable to regard as false even those things that are merely uncertain but possibly true. In addition, it gets around the unenviable position of calling God a deceiver. Nonetheless, the fact that Descartes has styled the demon as a supremely powerful being has raised eyebrows even in then relatively liberal Holland. More recent variations on this theme of profound illusions include virtual machines, a brain in a vat, collectively induced delusions (a suggestive example is depicted in "The Matrix": the evil demon is the matrix itself). Or, if we choose to regard sensory perceptions as an in principle inadequate rendering of the true structure of the universe, we may say with Albert Einstein: "Reality is merely an illusion, albeit a very persistent one."
All powerful God can deceive me.
All good God probably will not.
Natural Forces unlikely to protect me from deception.
Evil Demon will most certainly enjoy deceiving me.

Therefore I cannot rule out the possibility of radical deception. Not even with regard to the good God (who am I to judge God's ways?). Thus I have run out of options.
Resolution: From now on I will suppose that all "objective things" that we see are nothing but illusions and dreams. I will consider myself as having no body, "yet falsely believing" that I have hands, eyes and the senses.
Why I am pushing my doubt beyond the limits of any reasonable doubt? Because I don't want to take any chances of being delivered to the whim of unnoticed deceptions. Thus I'll rather sacrifice some probable beliefs than fall prey to the lure of uncertainties.
  Descartes' logic works like this: If I cannot get any positive and absolute truth I'll make sure at least not to succumb to any falsity.
Note: Descartes refers to certainty when he uses the phrase "the knowledge of the truth"(three times!).
Human Weakness: Descartes is aware that his epistemological vigilance requires absolute seriousness with this otherwise unlikely hypothesis, and consequently, he needs to guard himself against the effects of the malign genius' existence even though these effects might never really occur. But it is hard to be consistently strict and rigid, particularly if such a stance is commanded by an insight that is not very agreeable. In real life we go by inclinations, not by philosophical insights. But he now knows at least that the "liberty" of ordinary life is imaginary and that it rests on illusions. On the other hand, these illusions are pleasant and Descartes is understandably "slow to wake up from this slumber..."  Thus it seems that the thinker (Descartes) is on the verge to relapse into the imaginary security of his previous opinions.
Note: Cf. the parallel with an inmate who enjoys the imaginary freedom while slumbering in a prison cell with the instructions of Morpheus in "The Matrix".


1. Does Descartes mean that the senses are not to be trusted at all? No, the critique of the senses does not entail that no sensory belief could be certain, only that such beliefs could not be regarded certain as long as we stay within the realm of common sense prejudices for the senses. 

2. How does Descartes know that his senses have sometimes deceived him? Of course, by using his senses? Is that a contradiction? Not necessarily. He does not claim that the senses are always deceptive. He only says he should not trust his senses completely. 

3. Are things in the world so arranged that knowledge must be fictitious? No, but doubt is advisable. 

4. How does Descartes know that sometimes his dreams are as vivid as waking perceptions? Is that a self-refuting statement? It is a performative contradiction, but it does not invalidate his argument, because he reports what he sincerely believes to be the case. In addition, he does not claim indiscernibility as a general principle. 

5. How can I know whether I am awake or sound asleep? The very question resolves the dilemma, because if I raise it I am not sound asleep (leaving aside the possibility of "lucid dreams"). Descartes does not claim that he is awake because there are differences between the concept of wake and sleep, but because he is able to consider the differences. 

6. Do skeptical remarks on simple concepts and obvious truths affect the assumption that rational inquiry is possible? Is the whole project of finding certainty hereby compromised? No. Mathematical propositions were put temporarily into doubt, until certainty is reached. 

7. Does Descartes want to make his mind completely empty (tabula rasa)? 
No, only not to take anything for granted.

8. How can we justify relying on reason and logical truths in conducting this inquiry? We simply cannot start philosophizing if we dismiss our reason. 


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