Ideas from 'Meditations' by René Descartes [1641], by Theme Structure

[found in 'Discourse on Method/The Meditations' by Descartes,René (ed/tr Sutcliffe,F.E.) [Penguin 1968,0-14-044206-5]].

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1. Philosophy / B. History of Ideas / 5. Later European Thought
Modern science comes from Descartes' view that knowledge doesn't need moral purity
                        Full Idea: Before Descartes, one could not be impure, immoral, and know the truth. After Descartes, direct evidence is enough, and we have a nonascetic subject of knowledge; this change makes possible the institutionalisation of modern science.
                        From: report of René Descartes (Meditations [1641]) by Michel Foucault - On the Genealogy of Ethics
                        A reaction: I would have thought Gassendi and the British Empiricists would be a more plausible source for this shift of attitude. Plato would relegate modern science to a lower level of knowledge.
2. Reason / A. Nature of Reason / 2. Logos
Descartes impoverished the classical idea of logos, and it no longer covered human experience
                        Full Idea: Descartes attacked and fundamentally altered classical logos. The result is an impoverished conception of reason, one that is unable to do justice to the significance and value of human experience.
                        From: comment on René Descartes (Meditations [1641]) by David Roochnik - The Tragedy of Reason Prol. Xii
2. Reason / A. Nature of Reason / 4. Aims of Reason
Reason says don't assent to uncertain principles, just as much as totally false ones
                        Full Idea: Reason now persuades me that I should withhold my assent no less carefully from opinions that are not completely certain and indubitable than I would from those that are patently false.
                        From: René Descartes (Meditations [1641], §1.18)
2. Reason / A. Nature of Reason / 7. Status of Reason
Since Plato all philosophers have followed the herd, except Descartes, stuck in superficial reason
                        Full Idea: Since Plato all philosophers have followed moral 'instinct', or 'faith', or (as I call it) 'the herd'. One might exclude Descartes, the father of rationalism, who recognised only reason - but reason is only an instrument, and Descartes was superficial.
                        From: comment on René Descartes (Meditations [1641]) by Friedrich Nietzsche - Beyond Good and Evil §191
2. Reason / F. Fallacies / 4. Circularity
Once it is clear that there is a God who is no deceiver, I conclude that clear and distinct perceptions must be true
                        Full Idea: Once I perceived that there is a God,…and that he is no deceiver, I then concluded that everything that I clearly and distinctly perceived is necessarily true.
                        From: René Descartes (Meditations [1641], §5.70)
                        A reaction: spotted by Arnauld
It is circular to make truth depend on believing God's existence is true
                        Full Idea: How does the author avoid reasoning in a circle when he says that we are sure that what we clearly and distinctly perceive is true only because God exists? But we can be sure that God exists only because we clearly and distinctly perceive this.
                        From: comment on René Descartes (Meditations [1641], §5.71) by Antoine Arnauld - Objections to 'Meditations' (Fourth) 214
Descartes is right that in the Christian view only God can guarantee the reliability of senses
                        Full Idea: Even Descartes had a notion that in a Christian mode of thought (where God is a good creator), only God's veracity guarantees to us the judgements of our senses.
                        From: comment on René Descartes (Meditations [1641], §5.71) by Friedrich Nietzsche - The Will to Power (notebooks) §436
                        A reaction: An unusual defence of the notorious Cartesian Circle. Of course, Descartes claims that God guarantees reason (as 'clear and distinct conception'), not senses, and only reason led Descartes to God.
3. Truth / A. Truth Problems / 8. Subjective Truth
My general rule is that everything that I perceive clearly and distinctly is true
                        Full Idea: I now seem able to posit as a general rule that everything I very clearly and distinctly perceive is true.
                        From: René Descartes (Meditations [1641], §3.35)
Someone may think a thing is 'clear and distinct', but be wrong
                        Full Idea: Leibniz objected to Descartes' theory of truth, saying that people may think something is clear and distinct, and yet be wrong.
                        From: comment on René Descartes (Meditations [1641], §3.36) by Gottfried Leibniz - works
                        A reaction: Quite so. Descartes has misunderstood what sort of concept 'truth' is meant to be. It's the usual confusion of epistemology and metaphysics. Truth is not a feature of the human mind.
5. Theory of Logic / C. Ontology of Logic / 3. If-Thenism
Arithmetic and geometry achieve some certainty without worrying about existence
                        Full Idea: Arithmetic, geometry and sciences of that kind only treat of things without taking any great trouble to ascertain whether they are actually existent or not, and contain some measure of certainty.
                        From: René Descartes (Meditations [1641], §1), quoted by Alan Musgrave - Logicism Revisited §4
                        A reaction: This is Musgrave's earliest quotation which seems to take the if-thenist view.
6. Mathematics / A. Nature of Mathematics / 1. Mathematics
Surely maths is true even if I am dreaming?
                        Full Idea: Surely whether I am asleep or awake, two plus three makes five, and a square does not have more than four sides.
                        From: René Descartes (Meditations [1641], §1.20)
I can learn the concepts of duration and number just from observing my own thoughts
                        Full Idea: When I think that I exist now, and recollect that I existed in the past, and when I conceive various thoughts, the number of which I know, then I acquire the ideas of duration and number which I can thereafter transfer to all the other objects I wish.
                        From: René Descartes (Meditations [1641], §3.44)
9. Objects / B. Unity of Objects / 1. Unifying an Object / c. Unity as conceptual
If I can separate two things in my understanding, then God can separate them in reality
                        Full Idea: My ability clearly and distinctly to understand one thing without another suffices to make me certain that the one thing is different from the other, since they can be separated from each other (at least by God).
                        From: René Descartes (Meditations [1641], §6.78)
9. Objects / B. Unity of Objects / 2. Substance / e. Substance critique
Substance cannot be conceived or explained to others
                        Full Idea: The alleged naked, or rather hidden, substance of wax is something that we can neither ourselves conceive nor explain to others.
                        From: comment on René Descartes (Meditations [1641], §2.31) by Pierre Gassendi - Objections to 'Meditations' (Fifth) 273
9. Objects / C. Structure of Objects / 7. Substratum
If we remove surface qualities from wax, we have an extended, flexible, changeable thing
                        Full Idea: After taking away what does not belong to the wax, let us see what is left: surely, it is nothing other than a thing that is extended, flexible and changeable.
                        From: René Descartes (Meditations [1641], (VII:30-1)), quoted by Robert Pasnau - Metaphysical Themes 1274-1671 08.2
                        A reaction: Aristotle worried about nothing being left when you 'stripped' an object, so this could be seen as a positive contribution to scholastic philosophy. Why is the substrate 'flexible'? He talks elsewhere of taking the clothes off the wax and seeing it naked.
9. Objects / D. Essence of Objects / 4. Essence as Definition
Descartes gives an essence by an encapsulating formula
                        Full Idea: For Descartes in providing an essence for an item [such as God, wax, or a mathematical kind] we provide an encapsulating formula defining the phenomenon.
                        From: report of René Descartes (Meditations [1641]) by Joseph Almog - Nature Without Essence I
                        A reaction: I argue that this is not what Aristotle intended be an essentialist definition, which can be quite long, like a scientific monograph. Descartes firmly rejected Aristotle's 'substantial form' as essence.
10. Modality / D. Knowledge of Modality / 1. A Priori Necessary
We know by thought that what is done cannot be undone
                        Full Idea: Some ideas belong exclusively to the mind, such as perceiving that what has been done cannot be undone, and everything else that is known by the light of nature.
                        From: René Descartes (Meditations [1641], §6.82)
10. Modality / D. Knowledge of Modality / 4. Conceivable as Possible / b. Conceivable but impossible
Pythagoras' Theorem doesn't cease to be part of the essence of triangles just because we doubt it
                        Full Idea: You can't reason 'I know the triangle is right-angled, but I doubt Pythagoras' Theorem, therefore it does not belong to the essence of right-angled triangles that the square on the hypotenuse is equal to the sum of the squares on the other two sides'.
                        From: comment on René Descartes (Meditations [1641], §6.78) by Antoine Arnauld - Objections to 'Meditations' (Fourth) 202
11. Knowledge Aims / A. Knowledge / 4. Belief / d. Cause of beliefs
Belief is not an intellectual state or act, because propositions are affirmed or denied by the will
                        Full Idea: Descartes claimed that belief is not purely an intellectual state or act, since it is not the intellect that affirms or denies a proposition proposed for its consideration, but the will.
                        From: report of René Descartes (Meditations [1641], IV) by Linda Trinkaus Zagzebski - Virtues of the Mind 4.2
                        A reaction: This is the canonical idea of 'doxastic voluntarism' - that we choose what to believe or not believe. In modern times this view has become deeply unfashionable. I don't we should wholly reject the possibility of choosing to believe something.
11. Knowledge Aims / B. Certain Knowledge / 1. Certainty
Maybe there is only one certain fact, which is that nothing is certain
                        Full Idea: If I suppose that everything I see is false. Nothing I remember actually existed. I have no senses, and body, shape, extension, movement and place are all chimeras. What then is true? Perhaps just the single fact that nothing is certain.
                        From: René Descartes (Meditations [1641], §2.24)
Descartes tried to model reason on maths instead of 'logos'
                        Full Idea: Descartes rejects logos because it does not achieve the certainty he craves. He replaces it with his own model of rationality, one modelled essentially on mathematics.
                        From: comment on René Descartes (Meditations [1641], §1) by David Roochnik - The Tragedy of Reason p.76
Labelling slightly doubtful things as false is irrational
                        Full Idea: To declare that which is the least bit dubious as absolutely false is to declare war on logos.
                        From: comment on René Descartes (Meditations [1641], §1.17) by David Roochnik - The Tragedy of Reason p.72
11. Knowledge Aims / B. Certain Knowledge / 4. The Cogito
"I am, I exist" is necessarily true every time I utter it or conceive it in my mind
                        Full Idea: "I am, I exist" is necessarily true every time I utter it or conceive it in my mind.
                        From: René Descartes (Meditations [1641], §2.25)
The Cogito is a transcendental argument, not a piece of a priori knowledge
                        Full Idea: The Cogito is a transcendental argument; Descartes doesn't claim that it is a priori that he exists, but that any doubt or denial that he exists would presuppose his existence.
                        From: comment on René Descartes (Meditations [1641], §2.26) by Georges Rey - Contemporary Philosophy of Mind 3.2.1
If I don't think, there is no reason to think that I exist
                        Full Idea: It could be that if I were to cease all thinking I would then utterly cease to exist. …I am therefore precisely nothing but a thinking thing; that is, a mind, or intellect, or understanding, or reason.
                        From: René Descartes (Meditations [1641], §2.27)
I must even exist if I am being deceived by something
                        Full Idea: Doubtless I exist if I persuade myself of something. But there is some powerful and cunning deceiver who is deliberately deceiving me. Then too there is no doubt that I exist, if he is deceiving me.
                        From: René Descartes (Meditations [1641], §2.25)
Descartes transformed 'God is thinkable, so he exists' into 'I think, so I exist'
                        Full Idea: Descartes transformed the proposition 'because God is thinkable, therefore he exists' into the proposition 'I think, therefore I am'.
                        From: report of René Descartes (Meditations [1641], 2) by Ludwig Feuerbach - Principles of Philosophy of the Future §18
                        A reaction: This implies that Descartes' foundation is the Ontological Argument rather than the Cogito. It certainly shows how a priori synthetic thinking is basic in Descartes - that views of existence derive from pure thought. Was Descartes an idealist?
In the Meditations version of the Cogito he says "I am; I exist", which avoids presenting it as an argument
                        Full Idea: Descartes may have been aware of the danger of begging the question (in claiming "I think therefore I am") because in 'Meditations' he says "I am; I exist", which is not presented in the form of an argument.
                        From: report of René Descartes (Meditations [1641], 2) by J Baggini / PS Fosl - The Philosopher's Toolkit §3.22
                        A reaction: Certainly the word 'therefore' cries out for a strict analysis of what is being inferred from what, but presenting the Cogito as a self-evident intuition for the 'natural light' has its own problems.
Modern philosophy set the self-conscious ego in place of God
                        Full Idea: Modern philosophy set the thinking being, the ego, and the self-conscious mind in the place of the merely ideated being, in place of God.
                        From: report of René Descartes (Meditations [1641]) by Ludwig Feuerbach - Principles of Philosophy of the Future §37
                        A reaction: Descartes would be shocked by this interpretation, but God comes third in his logical priorities, after the existence of his ego, and its reliance on what is clear and distinct.
"I think therefore I am" is the absolute truth of consciousness
                        Full Idea: "I think therefore I am" is the absolute truth of consciousness as it attains to itself.
                        From: comment on René Descartes (Meditations [1641], §2) by Jean-Paul Sartre - Existentialism and Humanism p.44
11. Knowledge Aims / B. Certain Knowledge / 5. Cogito Critique
The Cogito proves subjective experience is basic, but makes false claims about the Self
                        Full Idea: The Cogito argument proves that subjective experience is the most reliable, but it makes unjustified claims about the certainty of the Self.
                        From: comment on René Descartes (Meditations [1641], §2.26) by Bertrand Russell - Problems of Philosophy Ch 2
It is a precondition of the use of the word 'I' that I exist
                        Full Idea: In the Cogito the work is all done by the demonstrative word 'I', because it is a precondition of the use of such a word that the thing to which it points has to exist.
                        From: comment on René Descartes (Meditations [1641], §2.26) by A.J. Ayer - The Problem of Knowledge Ch 2 (iii)
Maybe 'I' am not the thinker, but something produced by thought
                        Full Idea: In the past one said 'I' is the condition, 'think' is the predicate and conditioned - thinking is an activity which the subject causes; but maybe the reverse is true - and 'I' is only a synthesis produced by thinking.
                        From: comment on René Descartes (Meditations [1641], §2.26) by Friedrich Nietzsche - Beyond Good and Evil §54
The thing which experiences may be momentary, and change with the next experience
                        Full Idea: It might be that the something which sees a brown colour is quite momentary, and not the same thing which has some different experience the next moment.
                        From: comment on René Descartes (Meditations [1641], §2.26) by Bertrand Russell - Problems of Philosophy Ch.2
                        A reaction: This has become one of the standard objections to the Cogito. Note that Descartes himself was aware of the problem (Idea 1400). Sometimes experiences make no sense if there isn't something connecting them to previous experiences.
'I think' assumes I exist, that thinking is known and caused, and that I am doing it
                        Full Idea: The sentence "I think" contains a series of unprovable assertions; for example, it is I who think, that it must be something at all which thinks, that thinking is by an entity thought of as a cause, that an 'I' exists, and that I know what thinking is.
                        From: comment on René Descartes (Meditations [1641], §2.26) by Friedrich Nietzsche - Beyond Good and Evil §16
A thought doesn't imply other thoughts, or enough thoughts to make up a self
                        Full Idea: The fact that a thought occurs at a given moment does not entail that any other thought has occurred at any other moment, still less that there has occurred a series of thoughts sufficient to constitute a single self.
                        From: comment on René Descartes (Meditations [1641], §2.26) by A.J. Ayer - Language,Truth and Logic Ch.2
                        A reaction: This seems to be the main objection to the Cogito. It doesn't refute it, but simply recommends cautious restraint in what is being claimed as its conclusion. I can't make much sense of a thought which has no thinker at all.
The Cogito only works if you already understand what thought and existence are
                        Full Idea: In order to be certain that you are thinking you must know what thought or thinking is, and what your existence is; but since you do not yet know what these things are, how can you know that you are thinking or that you exist?
                        From: comment on René Descartes (Meditations [1641], §2.26) by Marin Mersenne - Objections to 'Meditations' (Sixth) 413
That I perform an activity (thinking) doesn't prove what type of thing I am
                        Full Idea: From the fact that I am thinking it follows that I exist, since that which thinks is not nothing. But when he adds 'that is, I am a mind, or intelligence, or intellect', a doubt arises. ..You might as well say 'I am walking, therefore I am a walk'.
                        From: comment on René Descartes (Meditations [1641], §2.26) by Thomas Hobbes - Objections to 'Meditations' (Third) 172
Autistic children seem to use the 'I' concept without seeing themselves as thinkers
                        Full Idea: It really does not seem (as a result of research into autism) that when one thinks of oneself with one's 'I' concept, one must thereby represent oneself as a thinker.
                        From: comment on René Descartes (Meditations [1641], §2.26) by Gabriel M.A. Segal - A Slim Book about Narrow Content 4.2
The Cogito assumes a priori the existence of substance, when actually it is a grammatical custom
                        Full Idea: Descartes' Cogito posits as 'true a priori' our belief in the concept of substance, but the idea that when there is a thought there has to be something 'that thinks' is simply a formulation of our grammatical custom that adds a doer to every deed.
                        From: comment on René Descartes (Meditations [1641], §2.26) by Friedrich Nietzsche - The Will to Power (notebooks) §484
                        A reaction: This anticipates the sort of thing Ayer and the logical positivists said. It is not clear that Descartes does think the mind is a substance, but this pinpoints a possible presupposition in Descartes.
How can we infer that all thinking involves self-consciousness, just from my own case?
                        Full Idea: It seems strange that the condition under which I think is to be valid for everything that thinks, and that on an empirical-seeming proposition we can presume to ground a universal judgement, that everything that thinks has self-consciousness.
                        From: comment on René Descartes (Meditations [1641], §2.26) by Immanuel Kant - Critique of Pure Reason A346
                        A reaction: Kant is not bothered by this, and says we know it a priori. If it is indeed an empirical proposition, it becomes an induction with one instance, which is the notorious weakness of the 'argument from analogy' to other minds. The Cogito is not empirical.
My self is not an inference from 'I think', but a presupposition of it
                        Full Idea: The simplicity of my self is not inferred from the proposition "I think", but rather the former lies in every thought. 'I am simple' is an immediate apperception, just as the Cogito is tautological, since 'cogito' immediately asserts the reality.
                        From: comment on René Descartes (Meditations [1641], §2.26) by Immanuel Kant - Critique of Pure Reason A355
                        A reaction: This is why Kant thinks the self is the result of a transcendental deduction, rather than of a direct observation of the self-evident. Personally I side with Descartes. I do not 'observe' my self, but I am acutely aware of its presence and actions.
We cannot give any information a priori about the nature of the 'thing that thinks'
                        Full Idea: If anyone asks me: What is the constitution of a thing that thinks? I do not know how to answer a priori, because the answer ought to be synthetic (for an analytic answer explains thinking, but gives no cognition of that on which thinking rests).
                        From: comment on René Descartes (Meditations [1641], §2.26) by Immanuel Kant - Critique of Pure Reason A398
                        A reaction: This has always seemed a problem with Descartes' very thin account of his 'res cogitans', but then what exactly does Kant want to know? Is it a metaphysical disaster if we think of the self as having no more identity than a geometrical point?
The fact that I am a subject is not enough evidence to show that I am a substantial object
                        Full Idea: The fact that I am a subject ..does not signify that as object I am a self-subsisting being or substance; the latter goes too far, and hence demands data that are not encountered at all in thinking.
                        From: comment on René Descartes (Meditations [1641], §2.26) by Immanuel Kant - Critique of Pure Reason B407
                        A reaction: This is a key problem with the Cogito - that so little can be said about the 'I' of which the existence has been proved that it is not clear that anything has been proved at all - certainly not that there is a continuous and stable Ego.
Descartes' claim to know his existence before his essence is misleading or absurd
                        Full Idea: Descartes claimed to know that he existed before he knew what he was - before he grasped his own essence. This is either disingenuous or intended non-literally, if it is not to be dismissed as incomprehensible.
                        From: report of René Descartes (Meditations [1641], 2) by E.J. Lowe - Two Notions of Being: Entity and Essence 2 n32
                        A reaction: If something comes at you from the mist, you can know that it exists before you know what it is. How could you understand the essence of something if you hadn't first encountered its existence? Lowe has it the wrong way round.
Modern self-consciousness is a doubtful abstraction; only senses and feelings are certain
                        Full Idea: The self-consciousness of modern philosophy is only a being ideated and mediated through abstraction and thus a doubtful being; certain and immediately assured is only that which is an object of the senses, perception and feeling.
                        From: comment on René Descartes (Meditations [1641], 2) by Ludwig Feuerbach - Principles of Philosophy of the Future §37
                        A reaction: This seems to agree with Hume's empirical doubts about the self (Idea 1316). The comment that 'abstraction' is involved in the Cogito argument is interesting. Descartes said the Cogito was a 'simply intuition of the mind' (Idea 3622).
11. Knowledge Aims / C. Knowing Reality / 2. Phenomenalism
My perceiving of things may be false, but my seeming to perceive them cannot be false
                        Full Idea: I now see a light, I hear a noise, I feel heat. Perhaps these things are false, since I am asleep. Yet I certainly do seem to see, hear, and feel warmth. This cannot be false.
                        From: René Descartes (Meditations [1641], §2.29)
11. Knowledge Aims / C. Knowing Reality / 4. Solipsism
I myself could be the author of all these self-delusions
                        Full Idea: I myself could be the author of all these self-delusions.
                        From: René Descartes (Meditations [1641], §2.24)
12. Knowledge Sources / A. A Priori Knowledge / 4. A Priori as Necessities
A triangle has a separate non-invented nature, shown by my ability to prove facts about it
                        Full Idea: A triangle has a determinate nature, which I did not fabricate, and which does not depend on my mind. This is evident from the fact that various properties can be demonstrated regarding it, such as that its three angles are equal to two right angles.
                        From: René Descartes (Meditations [1641], §5.64)
12. Knowledge Sources / B. Perception / 2. Qualities in Perception / c. Primary qualities
For Descartes, objects have one primary quality, which is geometrical
                        Full Idea: Descartes denies any similarity between the physical world and ideas, as matter possesses only geometrical properties; Locke allows more primary qualities, but follows Boyle and the atomists in treating secondary qualities as creations of sense.
                        From: report of René Descartes (Meditations [1641]) by Howard Robinson - Perception 1.5
                        A reaction: The interesting point to note here is that Descartes' geometrical view of objects (they are defined purely by 'extension') is the view that they have one minimal primary quality. I prefer Locke's view, of which the history (given here) is interesting.
12. Knowledge Sources / B. Perception / 5. Interpretation
Why does pain make us sad?
                        Full Idea: Why should a certain sadness of spirit arise from a sensation of pain?
                        From: René Descartes (Meditations [1641], §6.76)
12. Knowledge Sources / C. Rationalism / 1. Rationalism
We perceive objects by intellect, not by senses or imagination
                        Full Idea: Bodies are not, properly speaking, perceived by the senses or by the faculty of imagination, but by the intellect alone.
                        From: René Descartes (Meditations [1641], §2.34)
The wax is not perceived by the senses, but by the mind alone
                        Full Idea: The perception of the wax is neither a seeing, nor a touching, nor an imagining. Rather, it is an inspection on the part of the mind alone.
                        From: René Descartes (Meditations [1641], §2.31)
Dogs can make the same judgements as us about variable things
                        Full Idea: A dog certainly makes similar kinds of judgement to your perceiving men by their hats and cloaks when they see their master's hat or clothes, …and they can recognise their master even if he is standing, sitting, lying down, or crouching.
                        From: comment on René Descartes (Meditations [1641], §2.32) by Pierre Gassendi - Objections to 'Meditations' (Fifth) 272
We don't 'see' men in heavy clothes, we judge them to be men
                        Full Idea: Were I to look out of my window and observe men crossing the square, I would ordinarily say that I see the men themselves. But what do I see but hats and clothes, which could conceal automata? Yet I judge them to be men.
                        From: René Descartes (Meditations [1641], §2.32)
13. Knowledge Criteria / B. Internal Justification / 4. Foundationalism / a. Foundationalism
To achieve good science we must rebuild from the foundations
                        Full Idea: Once in my life I had to raze everything to the ground and begin again from the original foundations, if I wanted to establish anything firm and lasting in the sciences.
                        From: René Descartes (Meditations [1641], §1.17)
                        A reaction: This sentence is the beginning of the Enlightenment. The project of proving absolutely everything, and in a foundational way, is now met with much scepticism. I will never abandon the project!
Only one certainty is needed for progress (like a lever's fulcrum)
                        Full Idea: Archimedes sought but one firm and immovable point in order to move the entire earth. Just so, great things are to be hoped for if I succeed in finding just one thing, however slight, that is certain and unshaken.
                        From: René Descartes (Meditations [1641], §2.24)
                        A reaction: The classic foundationalist difficulty is that you may find something totally certain, but is it a fulcrum? Or is it just minimal, boring and useless?
13. Knowledge Criteria / D. Scepticism / 1. Scepticism
Even if my body and objects are imaginary, there may be simpler things which are true
                        Full Idea: Perhaps even though general things like eyes could be imaginary, still one must admit that certain other things that are even more simple and universal are true.
                        From: René Descartes (Meditations [1641], §1.20)
Descartes can't begin again, because sceptics doubt cognitive processes as well as beliefs
                        Full Idea: Descartes' strategy of starting over will not work, because the skeptic is not just questioning our beliefs, he is also questioning the cognitive processes by which we arrive at our beliefs, and if we start all over again we use the same processes.
                        From: comment on René Descartes (Meditations [1641], §1) by J Pollock / J Cruz - Contemporary theories of Knowledge (2nd)
                        A reaction: Scepticism comes in degrees, so there is not one strategy employed by sceptics. It is certainly true, though, that nothing can resist extreme scepticism. The most extreme view is to refuse to accept the meaningfulness of all belief language.
13. Knowledge Criteria / D. Scepticism / 3. Illusion Scepticism
If pain is felt in a lost limb, I cannot be certain that a felt pain exists in my real limbs
                        Full Idea: I have heard it said by people whose arm or leg has been amputated that they still sensed pain in the lost limb. Thus it does not seem certain that one of my bodily members causes me pain, even though I sense pain in it.
                        From: René Descartes (Meditations [1641], §6.77)
The senses can only report, so perception errors are in the judgment
                        Full Idea: Although there is deception or falsity, it is not to be found in the senses; for the sense are quite passive and report only appearances, which must appear the way they do owing to their causes. The error or falsity is in the judgement or the mind.
                        From: comment on René Descartes (Meditations [1641], §1.18) by Pierre Gassendi - Objections to 'Meditations' (Fifth) 332
We correct sense errors with other senses, not intellect
                        Full Idea: Owing to refraction a stick which is in fact straight appears bent in water. What corrects the error? The intellect? Not at all; it is the sense of touch.
                        From: comment on René Descartes (Meditations [1641], §1.18) by Marin Mersenne - Objections to 'Meditations' (Sixth) 418
It is prudent never to trust your senses if they have deceived you even once
                        Full Idea: The senses are sometimes deceptive, and it is a mark of prudence never to place our complete trust in those who have deceived us even once.
                        From: René Descartes (Meditations [1641], §1.18)
13. Knowledge Criteria / D. Scepticism / 4. Demon Scepticism
God may have created nothing, but made his creation appear to me as it does now
                        Full Idea: How do I know that God did not bring it about that there is no earth or heavens, no extension, shape, size or place, and yet that all these things appear to me precisely as they do now?
                        From: René Descartes (Meditations [1641], §1.21)
To achieve full scepticism, I imagine a devil who deceives me about the external world and my own body and senses
                        Full Idea: I will suppose an evil genius, supremely powerful and clever, who has directed his entire effort at deceiving me. I will regard all external things as devilish hoaxes, and myself as not possessed of a body or senses, but falsely believing these things.
                        From: René Descartes (Meditations [1641], §1.22)
13. Knowledge Criteria / D. Scepticism / 5. Dream Scepticism
Waking actions are joined by memory to all our other actions, unlike actions of which we dream
                        Full Idea: Dreams are never joined by the memory with all the actions of life, as is the case with those actions that occur when one is awake.
                        From: René Descartes (Meditations [1641], §6.89)
13. Knowledge Criteria / D. Scepticism / 6. Scepticism Critique
I can only sense an object if it is present, and can't fail to sense it when it is
                        Full Idea: Perceptions come upon me without my consent, to the extent that, wish as I may, I could not sense any object unless it was present to a sense organ, nor could I fail to sense it when it was present.
                        From: René Descartes (Meditations [1641], §6.75)
15. Nature of Minds / A. Nature of Mind / 3. Mental Causation
Can the pineal gland be moved more slowly or quickly by the mind than by animal spirits?
                        Full Idea: I am in ignorance whether the pineal gland can be agitated more slowly or more quickly by the mind than by the animal spirits.
                        From: comment on René Descartes (Meditations [1641], §6.82) by Baruch de Spinoza - The Ethics V Pref
                        A reaction: Is this the earliest statement of the problem of double causation? It is a classic difficulty for dualists, highlighted by Ryle, among others. Avoidance of double causation is a classic reason for moving to monism about mind.
15. Nature of Minds / A. Nature of Mind / 4. Other Minds / c. Knowing other minds
We discovers others as well as ourselves in the Cogito
                        Full Idea: It is not only oneself that one discovers in the Cogito, but those of others too.
                        From: comment on René Descartes (Meditations [1641], §2) by Jean-Paul Sartre - Existentialism and Humanism p.45
                        A reaction: The analytical tradition requires a bit more than an instant perception of others in oneself. The problem of 'other minds' must at least be mentioned. However, the way to get to know a universal is to fully study a single instance.
15. Nature of Minds / A. Nature of Mind / 5. Unity of Mind
Faculties of the mind aren't parts, as one mind uses them
                        Full Idea: The faculties of willing, sensing, understanding and so on cannot be called "parts" of the mind, since it is one and the same mind that wills, senses and understands.
                        From: René Descartes (Meditations [1641], §6.86)
                        A reaction: It is best here to say that Descartes has confused the 'mind' with the 'person'. These faculties make (I think) no sense without a person to perform them, but the 'mind' surely includes these conscious activities, and many fringe events as well.
15. Nature of Minds / B. Features of Minds / 5. Qualia / a. Nature of qualia
Descartes put thought at the centre of the mind problem, but we put sensation
                        Full Idea: Descartes confined his dualism to problems of reason and language. Sensation and even imagination seemed to him physically unproblematic. Nowadays it is the reverse: thinking seems easy - but feeling?
                        From: comment on René Descartes (Meditations [1641], 2) by Georges Rey - Contemporary Philosophy of Mind 2 n16
                        A reaction: Thinking only 'seems easy' if it can be done without consciousness, and that is beginning to look like a dubious assumption. The most interesting and promising area is the borderline between a chess-playing machine and a human chess player.
15. Nature of Minds / C. Capacities of Minds / 1. Faculties
Descartes mentions many cognitive faculties, but reduces them to will and intellect
                        Full Idea: Although Descartes accepted a variety of cognitive faculties like the intellect, will, power of judgement, imagination, memory, and perception, he took them all to be ultimately reducible to different operations of the will and intellect.
                        From: report of René Descartes (Meditations [1641], 4) by Stephan Schmid - Faculties in Early Modern Philosophy 2
                        A reaction: In Med 4, it is most clear, when he reduces 'judgement' to will and intellect, which enable his to assent to an idea. Nietzsche saw Descartes' view as simplistic.
15. Nature of Minds / C. Capacities of Minds / 2. Imagination
Imagination and sensation are non-essential to mind
                        Full Idea: This power of imagination which is in me, in so far as it differs from the power of conceiving, is in no way necessary to my nature or essence.
                        From: René Descartes (Meditations [1641], §6.73)
                        A reaction: This is my candidate for the biggest blunder ever made by a great philosopher. But it was thanks to his mistake that I began to realise how totally central imagination is to the very act of thinking. Thank you, René.
16. Persons / A. Concept of a Person / 1. Existence of Persons
Some cause must unite the separate temporal sections of a person
                        Full Idea: Because the entire span of one's life can be divided into countless parts, each one wholly independent of the rest, it does not follow from the fact that I existed a short time ago that I exist now, unless some cause creates and preserves me each moment.
                        From: René Descartes (Meditations [1641], §3.49)
                        A reaction: How could I 'prove' that this computer is the same computer as it was five minutes ago, even after I have accepted the straightforward existence of the computer? This is the Enlightenment Project, the mad desire to prove absolutely everything.
16. Persons / D. Continuity of the Self / 7. Self and Thinking
Since I only observe myself to be thinking, I conclude that that is my essence
                        Full Idea: Since I do not observe that any other thing belongs necessarily to my nature or essence except that I am a thinking thing, I rightly conclude that my essence consists in this alone, that I am a thinking thing, or substance whose essence is thinking.
                        From: René Descartes (Meditations [1641], §6.78)
                        A reaction: This actually appears to be my favourite confusion - of episemology with ontology. Compare 'whenever I see him he is smiling, so he must be happy'. Personally I am happy to say that my essence is thinking, as long as it needn't be conscious.
I can exist without imagination and sensing, but they can't exist without me
                        Full Idea: I can understand myself without the faculties of imagining and sensing, but not vice versa; I cannot understand them without me - a substance endowed with understanding.
                        From: René Descartes (Meditations [1641], §6.78)
                        A reaction: I think this is a fundamental and important error on Descartes' part. The idea that understanding is possible without imagination (and even sensation) is wrong, and it leads to the misleading concept of 'pure' reason.
For Descartes a person's essence is the mind because objects are perceived by mind, not senses
                        Full Idea: For Descartes the essence of corporeal things is not an object of the senses, but only of the mind; and hence it is not the senses but the mind that is the essence of the perceiving subject, that is, of man.
                        From: report of René Descartes (Meditations [1641], 2) by Ludwig Feuerbach - Principles of Philosophy of the Future §17
                        A reaction: This, of course, is why Descartes' approach can lead to idealism and solipsism, whereas the other approach leads to empiricism and animalism (Idea 6669).
16. Persons / F. Free Will / 1. Nature of Free Will
Our 'will' just consists of the feeling that when we are motivated to do something, there are no external pressures
                        Full Idea: The will consists solely in the fact that when something is proposed to us by our intellect either to affirm or deny, we are moved in such a way that we sense we are determined to it by no external force.
                        From: René Descartes (Meditations [1641], §4.57)
16. Persons / F. Free Will / 4. For Free Will
My capacity to make choices with my free will extends as far as any faculty ever could
                        Full Idea: I experience that the will or free choice I have received from God is limited by no boundaries whatever, …indeed it is so great in me that I cannot grasp the idea of any greater faculty.
                        From: René Descartes (Meditations [1641], §4.56)
17. Mind and Body / A. Mind-Body Dualism / 1. Dualism
The mind is a non-extended thing which thinks
                        Full Idea: My concept of the human mind is a thinking thing, not extended in length, breadth or depth, and having nothing else from the body.
                        From: René Descartes (Meditations [1641], §4.53)
                        A reaction: But he admits (in Med 6) that the mind is so closely integrated with the body that they seem inseparable. Perhaps he shouldn't trust his own concept of the thing, because he is too close to the subject matter. You can't count a crowd if you are in it.
Mind is not extended, unlike the body
                        Full Idea: Since I am clearly a thinking thing and not an extended thing, and on the other hand I have a distinct idea of a body, as merely an extended thing and not a thinking thing, it is certain that I am really distinct from my body, and can exist without it.
                        From: René Descartes (Meditations [1641], §6.78)
                        A reaction: How can he be 'certain' for this reason? This is a classic confusion of ontology and epistemology. Given that the mind is a special case, he should be asking WHY his thinking is clear to him, but his body isn't. Maybe it is because of his viewpoint.
Descartes is a substance AND property dualist
                        Full Idea: Descartes' dualism combines substance dualism and property dualism; two disparate domains of substances, and two mutually exclusive families of properties.
                        From: report of René Descartes (Meditations [1641], §6.78) by Jaegwon Kim - Philosophy of Mind p.211
                        A reaction: I would have thought that substance dualism entailed property dualism. How would you distinguish two substances from one another except by their properties? There seems a merely logical possibility that God gives two substances the same properties.
The mind is utterly indivisible
                        Full Idea: There is a great difference between a mind and a body, in that a body, by its very nature, is always divisible, but the mind is utterly indivisible.
                        From: René Descartes (Meditations [1641], §6.85)
                        A reaction: This strikes me as being simply false. I don't just mean that surgeons can split the mind in half. We should think of the mind as a team of conscious and non-conscious processes, which are held together by a self in normal healthy people. Selves change.
17. Mind and Body / A. Mind-Body Dualism / 2. Interactionism
Interaction between mental and physical seems to violate the principle of conservation of energy
                        Full Idea: It is often argued that any interaction between the physical and the mental - as defined by Descartes - would require a violation of the first law of thermodynamics, the principle of conservation of energy.
                        From: comment on René Descartes (Meditations [1641]) by Mark Rowlands - Externalism Ch.2
                        A reaction: This would be because consciousness is adding energy to the system (in order to generate movement) without it having come from anywhere else in the physical system. A good objection, which only a miracle could overcome.
17. Mind and Body / A. Mind-Body Dualism / 8. Dualism of Mind Critique
The 'thinking thing' may be the physical basis of the mind
                        Full Idea: It may be that the thing that thinks is the subject to which mind, reason or intellect belong; and this subject may thus be something corporeal.
                        From: comment on René Descartes (Meditations [1641], §2.27) by Thomas Hobbes - Objections to 'Meditations' (Third) 173
                        A reaction: Of course, Descartes goes on to reject this view. Presumably he is suggesting that mind etc. might be properties of something corporeal, rather than being identical with it. Descartes was well aware of materialism in Hobbes and Gassendi.
Knowing different aspects of brain/mind doesn't make them different
                        Full Idea: Why should an epistemic distinction reflect an ontological distinction? Why should our epistemic privilege of being incorrigible about how things seem to us reflect a distinction between two realms of being?
                        From: comment on René Descartes (Meditations [1641], §6.78) by Richard Rorty - Philosophy and the Mirror of Nature 1.2
                        A reaction: This strikes me as being one of the most important ideas in philosophy, mainly as a corrective to a lot of bad philosophy, rather than as wisdom offered to non-philosophers (for whom Rorty's thought is probably common sense. How is it? How do we know?
Descartes gives no clear criterion for individuating mental substances
                        Full Idea: Descartes gives no clear criterion for individuating mental substances.
                        From: comment on René Descartes (Meditations [1641], §6.78) by John Cottingham - The Rationalists p.86
                        A reaction: Presumably I can individuate my own mind by the 'natural light' of reason, and the implications of the Cogito. The minds of others do seem to be a problem. Why should they coincide with bodies, and not overlap or blend or swap?
Does Descartes have a clear conception of how mind unites with body?
                        Full Idea: What does Descartes understand by the union of the mind and the body? What clear and distinct conception has he got of thought in most intimate union with a certain particle of extended matter?
                        From: comment on René Descartes (Meditations [1641], §6.82) by Baruch de Spinoza - The Ethics V Pref
                        A reaction: This is the classic, original and strongest objection to Cartesian dualism - that mind and body are held to be too different to interact. Spinoza may have overreacted a bit when he saw the only solution as the total identity of the two things.
Even Descartes may concede that mental supervenes on neuroanatomical
                        Full Idea: Even Descartes may have conceded that the mental supervenes on the neuroanatomical.
                        From: comment on René Descartes (Meditations [1641], 6) by William Lycan - Consciousness 5.2
                        A reaction: This is true (early in Meditation Six) despite his later suggestion of the pineal gland as the linking point. It proves nothing, but I have heard John Cottingham suggest that Descartes might well be a materialist if he came back today.
Superman's strength is indubitable, Clark Kent's is doubtful, so they are not the same?
                        Full Idea: Descartes's claim that mind and body are separate because the first is necessary when thinking and the second isn't, is like arguing 'Superman's strength is indubitable; Clark Kent's strength is widely doubted; so Clark Kent is not Superman'.
                        From: comment on René Descartes (Meditations [1641], p.156) by Keith T. Maslin - Introduction to the Philosophy of Mind 2.7.1
                        A reaction: I've heard people defend Descartes on this, and Kripke is interesting on the subject, but Descartes had better not be following this pattern of argument, or else a great philosopher would really be presenting an absurdity.
18. Thought / A. Modes of Thought / 2. Propositional Attitudes
In some thoughts I grasp a subject, but also I will or fear or affirm or deny it
                        Full Idea: Other thoughts are different from ideas, as when I will, or fear, or affirm, or deny, there is always some thing that I grasp as the subject of my thought, yet I embrace in my thought something more than the likeness of that thing.
                        From: René Descartes (Meditations [1641], §3.37)
                        A reaction: Note that the class of mental events we call 'propositional attitudes' had already been identified by Descartes. His categories of thinking in Med. Three might be one of his most important contributions, because that is what matters in the mind.
18. Thought / A. Modes of Thought / 5. Rationality / b. Human rationality
Descartes created the modern view of rationality, as an internal feature instead of an external vision
                        Full Idea: Rationality is now an internal property of subjective thinking, rather than its consisting in (according to Plato) its vision of reality. This view of Descartes' has become the standard modern view.
                        From: report of René Descartes (Meditations [1641]) by Charles Taylor - Sources of the Self §8
                        A reaction: Greek 'logos' actually seemed to be both internal and external. We have certainly lost the idea that the universe is rational, even though it is ordered.
18. Thought / A. Modes of Thought / 6. Judgement / b. Error
I make errors because my will extends beyond my understanding
                        Full Idea: My errors are owing simply to the fact that, since the will extends further than the intellect, I do not contain the will within the same boundaries, but extend it to things I do not understand.
                        From: René Descartes (Meditations [1641], §4.58)
18. Thought / C. Content / 2. Ideas
True ideas are images, such as of a man, a chimera, or God
                        Full Idea: Some of my thoughts are like images of things; to these alone does the word 'idea' properly apply, as when I think of a man, or a chimera, or the sky, or an angel, or God.
                        From: René Descartes (Meditations [1641], §3.37)
                        A reaction: Descartes is obviously aware of a problem with the application of the word 'idea'. This definition seems rather narrow (and visual), but it is certainly confined to concepts, and does not expand to include propositions.
18. Thought / C. Content / 10. Causal Semantics
All ideas are adventitious, and come from the senses
                        Full Idea: I would go further than you and note that all our ideas seem to be adventitious - to proceed from things which exist outside the mind and come under one of our senses. ..The idea of a giant is a man of ordinary size which the mind enlarges at will.
                        From: comment on René Descartes (Meditations [1641], §3.38) by Pierre Gassendi - Objections to 'Meditations' (Fifth) 280
                        A reaction: A classic early statement of modern empiricism. Gassendi needed to think about logic, maths, and necessities to make his case more secure. Where did his idea to 'enlarge' the giant come from?
18. Thought / D. Concepts / 2. Origin of Concepts / c. Nativist concepts
The ideas of God and of my self are innate in me
                        Full Idea: The idea of God is innate in me, just as the idea of myself is innate in me.
                        From: René Descartes (Meditations [1641], §3.51)
I can think of innumerable shapes I have never experienced
                        Full Idea: I can think of countless geometrical figures, concerning which there can be no suspicion of their ever having entered me through the senses.
                        From: René Descartes (Meditations [1641], §5.64)
The idea of a supremely perfect being is within me, like the basic concepts of mathematics
                        Full Idea: The idea of God, that is, the idea of a supremely perfect being, is one discovered to be no less within me than the idea of any figure or number.
                        From: René Descartes (Meditations [1641], §5.65)
26. Natural Theory / A. Speculations on Nature / 2. Natural Purpose / a. Final purpose
Many causes are quite baffling, so it is absurd to deduce causes from final purposes
                        Full Idea: God can make unnumerable things whose cause escapes me, and for this reason alone the entire class of causes which people customarily derive from a thing's "end", I judge to be utterly useless in physics.
                        From: René Descartes (Meditations [1641], §4.55)
                        A reaction: anti-Aristotle
26. Natural Theory / C. Causation / 8. Particular Causation / c. Conditions of causation
There must be at least as much in the cause as there is in the effect
                        Full Idea: There must be at least as much in the cause as there is in the effect.
                        From: René Descartes (Meditations [1641], §3.49)
28. God / A. Divine Nature / 2. Divine Nature
God the creator is an intelligent, infinite, powerful substance
                        Full Idea: I understand by the name "God" a certain substance that is infinite, independent, supremely intelligent and supremely powerful, and created me along with everything that exists.
                        From: René Descartes (Meditations [1641], §3.45)
Nothing apart from God could have essential existence, and such a being must be unique and eternal
                        Full Idea: I cannot think of anything aside from God alone to whose essence existence belongs, and I cannot conceive of two or more such Gods. I also perceive that God must be eternal, and have other perfect qualities.
                        From: René Descartes (Meditations [1641], §5.68)
28. God / A. Divine Nature / 3. Divine Perfections
It is self-evident that deception is a natural defect, so God could not be a deceiver
                        Full Idea: It is quite obvious that a perfect God cannot be a deceiver, for it is manifest by the light of nature that all fraud and deception depend on some defect.
                        From: René Descartes (Meditations [1641], §3.52)
28. God / B. Proving God / 2. Proofs of Reason / a. Ontological Proof
Existence and God's essence are inseparable, like a valley and a mountain, or a triangle and its properties
                        Full Idea: Existence can no more be separated from God's essence than its having three angles equal to two right angles can be separated from the essence of a triangle, or than the idea of a valley can be separated from the idea of a mountain.
                        From: René Descartes (Meditations [1641], §5.66)
One idea leads to another, but there must be an initial idea that contains the reality of all the others
                        Full Idea: Although one idea can perhaps issue from another, nevertheless no infinite regress is permitted here; eventually some first idea must be reached whose cause is a sort of archetype that contains formally all the reality that is in the idea.
                        From: René Descartes (Meditations [1641], §3.42)
The idea of God in my mind is like the mark a craftsman puts on his work
                        Full Idea: In creating me, God has endowed me with the idea of God, so that it would be like the mark of the craftsman impressed upon his work, although this mark need not be something distinct from the work itself.
                        From: René Descartes (Meditations [1641], §3.51)
I cannot think of a supremely perfect being without the supreme perfection of existence
                        Full Idea: I am not free to think of God without existence, that is, a supremely perfect being without a supreme perfection.
                        From: René Descartes (Meditations [1641], §5.67)
28. God / B. Proving God / 2. Proofs of Reason / b. Ontological Proof critique
We can never conceive of an infinite being
                        Full Idea: The human intellect is not capable of conceiving of infinity, and hence it neither has nor can contemplate any idea representing an infinite thing.
                        From: comment on René Descartes (Meditations [1641], §5.65) by Pierre Gassendi - Objections to 'Meditations' (Fifth) 286
Descartes cannot assume that a most perfect being exists without contradictions
                        Full Idea: Descartes' error is in assuming without proof that a most perfect being does not involve a contradiction.
                        From: comment on René Descartes (Meditations [1641], §5.67) by Gottfried Leibniz - A Specimen of Discoveries p.76
                        A reaction: Certainly Descartes seems obliged to grasp the concept of God 'clearly and distinctly', so there must be an absence of contradictions. But does Descartes have to prove that there are no contradictions in his concept of a triangle? Is self-evidence enough?
We mustn't worship God as an image because we have no idea of him
                        Full Idea: We are forbidden to worship God in the form of an image, for otherwise we might think that we were conceiving of him who is incapable of being conceived. It seems, then, that there is no idea of God in us.
                        From: comment on René Descartes (Meditations [1641], §5.65) by Thomas Hobbes - Objections to 'Meditations' (Third) 180
Existence is not a perfection; it is what makes perfection possible
                        Full Idea: Existence is not a perfection in God or in anything else; it is that without which no perfections can be present.
                        From: comment on René Descartes (Meditations [1641], §5.67) by Pierre Gassendi - Objections to 'Meditations' (Fifth) 323
29. Religion / D. Religious Issues / 3. Problem of Evil / c. Human Error
Error arises because my faculty for judging truth is not infinite
                        Full Idea: I make mistakes because the faculty of judging the truth, which I got from God, is not, in my case, infinite.
                        From: René Descartes (Meditations [1641], §4.54)
God didn't give us good judgement even about our own lives
                        Full Idea: God is not to be blamed for giving puny man a faculty of judging that is too small to cope with everything, but we may still wonder why our judgement is uncertain, confused and inadequate even for the few matters he did want us to decide upon.
                        From: comment on René Descartes (Meditations [1641], §4.58) by Pierre Gassendi - Objections to 'Meditations' (Fifth) 314
Since God does not wish to deceive me, my judgement won't make errors if I use it properly
                        Full Idea: Since God does not wish to deceive me, he assuredly has not given me a faculty of judgement with which I could never make a mistake, when I use it properly.
                        From: René Descartes (Meditations [1641], §4.54)
29. Religion / D. Religious Issues / 3. Problem of Evil / d. Natural Evil
If we ask whether God's works are perfect, we must not take a narrow viewpoint, but look at the universe as a whole
                        Full Idea: Whenever we ask whether the works of God are perfect, we should keep in view not simply some one creature in isolation from the rest, but the universe as a whole.
                        From: René Descartes (Meditations [1641], §4.55)