Ideas of René Descartes, by Theme

[French, 1596 - 1650, Born at La Haye. Pupil at Jesuit College. Lived mostly in Holland. Died working for Queen Christina in Stockholm.]

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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 [Foucault]
1. Philosophy / D. Nature of Philosophy / 1. Philosophy
Slow and accurate thought makes the greatest progress
1. Philosophy / D. Nature of Philosophy / 2. Invocation to Philosophy
The greatest good for a state is true philosophers
1. Philosophy / D. Nature of Philosophy / 7. Despair over Philosophy
Clever scholars can obscure things which are obvious even to peasants
Most things in human life seem vain and useless
Almost every daft idea has been expressed by some philosopher
1. Philosophy / E. Nature of Metaphysics / 4. Metaphysics as Science
Metaphysics is the roots of the tree of science
1. Philosophy / F. Analytic Philosophy / 5. Linguistic Analysis
Most scholastic disputes concern words, where agreeing on meanings would settle them
1. Philosophy / G. Scientific Philosophy / 3. Scientism
My Meditations are the complete foundation of my physics
2. Reason / A. Nature of Reason / 2. Logos
Descartes impoverished the classical idea of logos, and it no longer covered human experience [Roochnik]
2. Reason / A. Nature of Reason / 4. Aims of Reason
The secret of the method is to recognise which thing in a series is the simplest
Methodical thinking is cautious, analytical, systematic, and panoramic [PG]
Reason says don't assent to uncertain principles, just as much as totally false ones
2. Reason / A. Nature of Reason / 5. Objectivity
One truth leads us to another
2. Reason / A. Nature of Reason / 7. Status of Reason
Since Plato all philosophers have followed the herd, except Descartes, stuck in superficial reason [Nietzsche]
2. Reason / F. Fallacies / 4. Circularity
Clear and distinct conceptions are true because a perfect God exists
Once it is clear that there is a God who is no deceiver, I conclude that clear and distinct perceptions must be true
It is circular to make truth depend on believing God's existence is true [Arnauld]
Descartes is right that in the Christian view only God can guarantee the reliability of senses [Nietzsche]
I know the truth that God exists and is the author of truth
3. Truth / A. Truth Problems / 2. Defining Truth
Truth is such a transcendentally clear notion that it cannot be further defined
3. Truth / A. Truth Problems / 8. Subjective Truth
Truth is clear and distinct conception - of which it is hard to be sure
My general rule is that everything that I perceive clearly and distinctly is true
Someone may think a thing is 'clear and distinct', but be wrong [Leibniz]
3. Truth / D. Coherence Truth / 1. Coherence Truth
All items of possible human knowledge are interconnected, and can be reached by inference
5. Theory of Logic / C. Ontology of Logic / 3. If-Thenism
Arithmetic and geometry achieve some certainty without worrying about existence
6. Mathematics / A. Nature of Mathematics / 1. Mathematics
Surely maths is true even if I am dreaming?
I can learn the concepts of duration and number just from observing my own thoughts
6. Mathematics / A. Nature of Mathematics / 3. Nature of Numbers / g. Real numbers
Descartes showed a one-one order-preserving match between points on a line and the real numbers [Hart,WD]
6. Mathematics / A. Nature of Mathematics / 4. Using Numbers / a. Units
Unity is something shared by many things, so in that respect they are equals
I can only see the proportion of two to three if there is a common measure - their unity
6. Mathematics / C. Sources of Mathematics / 4. Mathematical Empiricism / c. Against mathematical empiricism
It is possible that an omnipotent God might make one and two fail to equal three
7. Existence / A. Nature of Existence / 3. Being / d. Non-being
Among the simples are the graspable negations, such as rest and instants
7. Existence / C. Structure of Existence / 5. Supervenience / c. Significance of supervenience
Two things being joined together doesn't prove they are the same
8. Modes of Existence / C. Powers and Dispositions / 2. Powers as Basic
Incorporeal substances are powers or forces [Pasnau]
8. Modes of Existence / C. Powers and Dispositions / 3. Powers as Derived
All powers can be explained by obvious features like size, shape and motion of matter
8. Modes of Existence / D. Universals / 1. Universals
Five universals: genus, species, difference, property, accident
8. Modes of Existence / E. Nominalism / 2. Resemblance Nominalism
A universal is a single idea applied to individual things that are similar to one another
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
9. Objects / B. Unity of Objects / 2. Substance / a. Substance
Knowing the attributes is enough to reveal a substance
If we perceive an attribute, we infer the existence of some substance
9. Objects / B. Unity of Objects / 2. Substance / d. Substance defined
A substance needs nothing else in order to exist
9. Objects / B. Unity of Objects / 2. Substance / e. Substance critique
Substance cannot be conceived or explained to others [Gassendi]
Descartes thinks distinguishing substances from aggregates is pointless [Pasnau]
9. Objects / C. Structure of Objects / 7. Substratum
If we remove surface qualities from wax, we have an extended, flexible, changeable thing
9. Objects / D. Essence of Objects / 4. Essence as Definition
Descartes gives an essence by an encapsulating formula [Almog]
9. Objects / D. Essence of Objects / 9. Essence and Properties
A substance has one principal property which is its nature and essence
9. Objects / D. Essence of Objects / 15. Against Essentialism
Substantial forms are not understood, and explain nothing
10. Modality / C. Sources of Modality / 4. Necessity from Concepts
3+4=7 is necessary because we cannot conceive of seven without including three and four
10. Modality / D. Knowledge of Modality / 1. A Priori Necessary
We know by thought that what is done cannot be undone
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 [Arnauld]
11. Knowledge Aims / A. Knowledge / 4. Belief / a. Beliefs
We can believe a thing without knowing we believe it
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 [Zagzebski]
11. Knowledge Aims / B. Certain Knowledge / 1. Certainty
If we accept mere probabilities as true we undermine our existing knowledge
In pursuing truth, anything less certain than mathematics is a waste of time
In morals Descartes accepts the conventional, but rejects it in epistemology [Roochnik]
Descartes tried to model reason on maths instead of 'logos' [Roochnik]
Labelling slightly doubtful things as false is irrational [Roochnik]
Maybe there is only one certain fact, which is that nothing is certain
Understanding, not the senses, gives certainty
11. Knowledge Aims / B. Certain Knowledge / 4. The Cogito
We all see intuitively that we exist, where intuition is attentive, clear and distinct rational understanding
When Socrates doubts, he know he doubts, and that truth is possible
In thinking everything else false, my own existence remains totally certain
The Cogito is not a syllogism but a self-evident intuition
Modern philosophy set the self-conscious ego in place of God [Feuerbach]
"I think therefore I am" is the absolute truth of consciousness [Sartre]
I must even exist if I am being deceived by something
"I am, I exist" is necessarily true every time I utter it or conceive it in my mind
The Cogito is a transcendental argument, not a piece of a priori knowledge [Rey]
If I don't think, there is no reason to think that I exist
Descartes transformed 'God is thinkable, so he exists' into 'I think, so I exist' [Feuerbach]
In the Meditations version of the Cogito he says "I am; I exist", which avoids presenting it as an argument [Baggini /Fosl]
I think, therefore I am, because for a thinking thing to not exist is a contradiction
'Thought' is all our conscious awareness, including feeling as well as understanding
Total doubt can't include your existence while doubting
11. Knowledge Aims / B. Certain Knowledge / 5. Cogito Critique
The Cogito only works if you already understand what thought and existence are [Mersenne]
It is a precondition of the use of the word 'I' that I exist [Ayer]
The thing which experiences may be momentary, and change with the next experience [Russell]
'I think' assumes I exist, that thinking is known and caused, and that I am doing it [Nietzsche]
A thought doesn't imply other thoughts, or enough thoughts to make up a self [Ayer]
That I perform an activity (thinking) doesn't prove what type of thing I am [Hobbes]
Autistic children seem to use the 'I' concept without seeing themselves as thinkers [Segal]
The Cogito assumes a priori the existence of substance, when actually it is a grammatical custom [Nietzsche]
How can we infer that all thinking involves self-consciousness, just from my own case? [Kant]
My self is not an inference from 'I think', but a presupposition of it [Kant]
We cannot give any information a priori about the nature of the 'thing that thinks' [Kant]
The fact that I am a subject is not enough evidence to show that I am a substantial object [Kant]
Descartes' claim to know his existence before his essence is misleading or absurd [Lowe]
Modern self-consciousness is a doubtful abstraction; only senses and feelings are certain [Feuerbach]
The Cogito proves subjective experience is basic, but makes false claims about the Self [Russell]
Maybe 'I' am not the thinker, but something produced by thought [Nietzsche]
11. Knowledge Aims / C. Knowing Reality / 2. Phenomenalism
My perceiving of things may be false, but my seeming to perceive them cannot be false
11. Knowledge Aims / C. Knowing Reality / 4. Solipsism
I myself could be the author of all these self-delusions
12. Knowledge Sources / A. A Priori Knowledge / 2. Self-Evidence
Clear and distinct truths must be known all at once (unlike deductions)
12. Knowledge Sources / A. A Priori Knowledge / 3. Innate Knowledge / a. Innate knowledge
Our souls possess divine seeds of knowledge, which can bear spontaneous fruit
Our thinking about external things doesn't disprove the existence of innate ideas
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
What experience could prove 'If a=c and b=c then a=b'?
'Nothing comes from nothing' is an eternal truth found within the mind
12. Knowledge Sources / A. A Priori Knowledge / 6. A Priori from Reason
I aim to find the principles and causes of everything, using the seeds within my mind
12. Knowledge Sources / B. Perception / 2. Qualities in Perception / c. Primary qualities
For Descartes, objects have one primary quality, which is geometrical [Robinson,H]
12. Knowledge Sources / B. Perception / 2. Qualities in Perception / d. Secondary qualities
Our sensation of light may not be the same as what produces the sensation
12. Knowledge Sources / B. Perception / 3. Representation
Descartes said images can refer to objects without resembling them (as words do) [Tuck]
12. Knowledge Sources / B. Perception / 5. Interpretation
Why does pain make us sad?
12. Knowledge Sources / C. Rationalism / 1. Rationalism
Understanding, rather than imagination or senses, gives knowledge
Dogs can make the same judgements as us about variable things [Gassendi]
We perceive objects by intellect, not by senses or imagination
The wax is not perceived by the senses, but by the mind alone
We don't 'see' men in heavy clothes, we judge them to be men
12. Knowledge Sources / D. Empiricism / 5. Empiricism Critique
If someone had only seen the basic colours, they could deduce the others from resemblance
13. Knowledge Criteria / B. Internal Justification / 4. Foundationalism / a. Foundationalism
The method starts with clear intuitions, followed by a process of deduction
I was searching for reliable rock under the shifting sand
To achieve good science we must rebuild from the foundations
Only one certainty is needed for progress (like a lever's fulcrum)
13. Knowledge Criteria / B. Internal Justification / 4. Foundationalism / b. Basic beliefs
We can know basic Principles without further knowledge, but not the other way round
13. Knowledge Criteria / D. Scepticism / 1. Scepticism
Even if my body and objects are imaginary, there may be simpler things which are true
Descartes can't begin again, because sceptics doubt cognitive processes as well as beliefs [Pollock/Cruz]
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
We correct sense errors with other senses, not intellect [Mersenne]
The senses can only report, so perception errors are in the judgment [Gassendi]
It is prudent never to trust your senses if they have deceived you even once
Only judgement decides which of our senses are reliable
13. Knowledge Criteria / D. Scepticism / 4. Demon Scepticism
God may have created nothing, but made his creation appear to me as it does now
To achieve full scepticism, I imagine a devil who deceives me about the external world and my own body and senses
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
13. Knowledge Criteria / D. Scepticism / 6. Scepticism Critique
When rebuilding a house, one needs alternative lodgings
I can only sense an object if it is present, and can't fail to sense it when it is
14. Science / A. Basis of Science / 3. Experiment
Only experiments can settle disagreements between rival explanations
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? [Spinoza]
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 [Sartre]
15. Nature of Minds / A. Nature of Mind / 5. Unity of Mind
Faculties of the mind aren't parts, as one mind uses them
15. Nature of Minds / A. Nature of Mind / 7. Animal Minds
Little reason is needed to speak, so animals have no reason at all
15. Nature of Minds / A. Nature of Mind / 8. Brain
Nerves and movement originate in the brain, where imagination moves them
15. Nature of Minds / B. Features of Minds / 1. Consciousness / b. Essence of consciousness
We can understand thinking occuring without imagination or sensation
15. Nature of Minds / B. Features of Minds / 2. Unconscious Mind
I can't be unaware of anything which is in me
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 [Rey]
15. Nature of Minds / C. Capacities of Minds / 1. Faculties
Our four knowledge faculties are intelligence, imagination, the senses, and memory
Descartes mentions many cognitive faculties, but reduces them to will and intellect [Schmid]
15. Nature of Minds / C. Capacities of Minds / 2. Imagination
Imagination and sensation are non-essential to mind
16. Persons / A. Concept of a Person / 1. Existence of Persons
Some cause must unite the separate temporal sections of a person
16. Persons / B. Nature of the Self / 3. Self as Non-physical
I am a thinking substance, which doesn't need a place or material support
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
I can exist without imagination and sensing, but they can't exist without me
For Descartes a person's essence is the mind because objects are perceived by mind, not senses [Feuerbach]
In thinking we shut ourselves off from other substances, showing our identity and separateness
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
Our free will is so self-evident to us that it must be a basic innate idea
16. Persons / F. Free Will / 3. Constraints on the will
The more reasons that compel me, the freer I am
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
We have inner awareness of our freedom
17. Mind and Body / A. Mind-Body Dualism / 1. Dualism
The force by which we know things is spiritual, and quite distinct from the body
I can deny my body and the world, but not my own existence
Reason is universal in its responses, but a physical machine is constrained by its organs
The mind is a non-extended thing which thinks
Mind is not extended, unlike the body
Descartes is a substance AND property dualist [Kim]
The mind is utterly indivisible
There are two ultimate classes of existence: thinking substance and extended substance
17. Mind and Body / A. Mind-Body Dualism / 2. Interactionism
The soul must unite with the body to have appetites and sensations
Interaction between mental and physical seems to violate the principle of conservation of energy [Rowlands]
Descartes discussed the interaction problem, and compared it with gravity [Lycan]
The pineal gland links soul to body, and unites the two symmetrical sides of the body [PG]
17. Mind and Body / A. Mind-Body Dualism / 8. Dualism of Mind Critique
The 'thinking thing' may be the physical basis of the mind [Hobbes]
Knowing different aspects of brain/mind doesn't make them different [Rorty]
Descartes gives no clear criterion for individuating mental substances [Cottingham]
Does Descartes have a clear conception of how mind unites with body? [Spinoza]
Even Descartes may concede that mental supervenes on neuroanatomical [Lycan]
Superman's strength is indubitable, Clark Kent's is doubtful, so they are not the same? [Maslin]
17. Mind and Body / D. Property Dualism / 5. Supervenience of mind
Even if tightly united, mind and body are different, as God could separate them
17. Mind and Body / E. Mind as Physical / 6. Conceptual Dualism
The concept of mind excludes body, and vice versa
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
18. Thought / A. Modes of Thought / 3. Emotions / c. Role of emotions
For Descartes passions are God-given preservers of the mind-body union [Taylor,C]
18. Thought / A. Modes of Thought / 3. Emotions / e. Basic emotions
Are there a few primary passions (say, joy, sadness and desire)? [Cottingham]
There are six primitive passions: wonder, love, hatred, desire, joy and sadness [Goldie]
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 [Taylor,C]
18. Thought / A. Modes of Thought / 6. Judgement / b. Error
I make errors because my will extends beyond my understanding
Most errors of judgement result from an inaccurate perception of the facts
18. Thought / B. Mechanics of Thought / 6. Artificial Thought / c. Turing Test
A machine could speak in response to physical stimulus, but not hold a conversation
18. Thought / C. Content / 2. Ideas
True ideas are images, such as of a man, a chimera, or God
18. Thought / C. Content / 10. Causal Semantics
All ideas are adventitious, and come from the senses [Gassendi]
18. Thought / D. Concepts / 2. Origin of Concepts / c. Nativist concepts
A blind man may still contain the idea of colour
The ideas of God and of my self are innate in me
I can think of innumerable shapes I have never experienced
The idea of a supremely perfect being is within me, like the basic concepts of mathematics
Qualia must be innate, because physical motions do not contain them
The mind's innate ideas are part of its capacity for thought
20. Action / B. Preliminaries of Action / 2. Willed Action / b. Volitionism
Merely willing to walk leads to our walking
20. Action / C. Motives for Action / 4. Responsibility for Actions
We do not praise the acts of an efficient automaton, as their acts are necessary
The greatest perfection of man is to act by free will, and thus merit praise or blame
22. Metaethics / B. Value / 2. Values / e. Death
We don't die because the soul departs; the soul departs because the organs cease functioning
23. Ethics / C. Virtue Theory / 1. Virtue Theory / d. Virtue theory critique
Greeks elevate virtues enormously, but never explain them
23. Ethics / C. Virtue Theory / 3. Virtues / a. Virtues
Descartes makes strength of will the central virtue [Taylor,C]
23. Ethics / F. Existentialism / 5. Existence-Essence
Essence must be known before we discuss existence
26. Natural Theory / A. Speculations on Nature / 1. Nature
Nature is devoid of thought [Meillassoux]
Physics only needs geometry or abstract mathematics, which can explain and demonstrate everything
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
26. Natural Theory / A. Speculations on Nature / 2. Natural Purpose / c. Purpose denied
We will not try to understand natural or divine ends, or final causes
26. Natural Theory / A. Speculations on Nature / 4. Mathematical Nature
All the sciences searching for order and measure are related to mathematics
26. Natural Theory / A. Speculations on Nature / 6. Early Matter Theories / f. Ancient elements
The Hot, Cold, Wet and Dry of the philosophers need themselves to be explained
26. Natural Theory / A. Speculations on Nature / 7. Later Matter Theories / c. Matter as extension
Matter can't just be Descartes's geometry, because a filler of the spaces is needed [Robinson,H]
Matter is not hard, heavy or coloured, but merely extended in space
Impenetrability only belongs to the essence of extension
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
26. Natural Theory / D. Laws of Nature / 7. Strictness of Laws
God has established laws throughout nature, and implanted ideas of them within us
27. Natural Reality / A. Classical Physics / 1. Mechanics / b. Laws of motion
Descartes said there was conservation of 'quantity of motion' [Papineau]
28. God / A. Divine Nature / 2. Divine Nature
God the creator is an intelligent, infinite, powerful substance
Nothing apart from God could have essential existence, and such a being must be unique and eternal
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
28. God / A. Divine Nature / 6. Divine Morality / d. God decrees morality
Ideas in God's mind only have value if he makes it so
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
The idea of God in my mind is like the mark a craftsman puts on his work
Necessary existence is a property which is uniquely part of God's essence
One idea leads to another, but there must be an initial idea that contains the reality of all the others
Possible existence is a perfection in the idea of a triangle
I cannot think of a supremely perfect being without the supreme perfection of existence
28. God / B. Proving God / 2. Proofs of Reason / b. Ontological Proof critique
We mustn't worship God as an image because we have no idea of him [Hobbes]
We can never conceive of an infinite being [Gassendi]
Descartes cannot assume that a most perfect being exists without contradictions [Leibniz]
Existence is not a perfection; it is what makes perfection possible [Gassendi]
28. God / B. Proving God / 3. Proofs of Evidence / a. Cosmological Proof
We can't prove a first cause from our inability to grasp infinity
28. God / C. Attitudes to God / 5. Atheism
Atheism is an atrocious and intolerable crime in any country
Atheism arises from empiricism, because God is intangible
29. Religion / B. Monotheistic Religion / 4. Christianity / c. Angels
An angelic mind would not experience pain, even when connected to a human body [Pasnau]
29. Religion / D. Religious Issues / 2. Immortality / b. Soul
I can't prove the soul is indestructible, only that it is separate from the mortal body
29. Religion / D. Religious Issues / 3. Problem of Evil / c. Human Error
God didn't give us good judgement even about our own lives [Gassendi]
Error arises because my faculty for judging truth is not infinite
Since God does not wish to deceive me, my judgement won't make errors if I use it properly
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