Combining Philosophers

All the ideas for Hermarchus, David Bostock and Ren Descartes

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350 ideas

1. Philosophy / B. History of Ideas / 5. Later European Thought
Modern science comes from Descartes' view that knowledge doesn't need moral purity [Descartes, by Foucault]
1. Philosophy / D. Nature of Philosophy / 1. Philosophy
Slow and accurate thought makes the greatest progress [Descartes]
1. Philosophy / D. Nature of Philosophy / 2. Invocation to Philosophy
The greatest good for a state is true philosophers [Descartes]
1. Philosophy / D. Nature of Philosophy / 7. Despair over Philosophy
Clever scholars can obscure things which are obvious even to peasants [Descartes]
Most things in human life seem vain and useless [Descartes]
Almost every daft idea has been expressed by some philosopher [Descartes]
1. Philosophy / E. Nature of Metaphysics / 4. Metaphysics as Science
Metaphysics is the roots of the tree of science [Descartes]
1. Philosophy / F. Analytic Philosophy / 5. Linguistic Analysis
Most scholastic disputes concern words, where agreeing on meanings would settle them [Descartes]
1. Philosophy / G. Scientific Philosophy / 3. Scientism
My Meditations are the complete foundation of my physics [Descartes]
2. Reason / A. Nature of Reason / 2. Logos
Descartes impoverished the classical idea of logos, and it no longer covered human experience [Roochnik on Descartes]
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 [Descartes]
Methodical thinking is cautious, analytical, systematic, and panoramic [Descartes, by PG]
Reason says don't assent to uncertain principles, just as much as totally false ones [Descartes]
2. Reason / A. Nature of Reason / 5. Objectivity
One truth leads us to another [Descartes]
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 on Descartes]
2. Reason / D. Definition / 8. Impredicative Definition
Impredicative definitions are wrong, because they change the set that is being defined? [Bostock]
2. Reason / F. Fallacies / 4. Circularity
It is circular to make truth depend on believing God's existence is true [Arnauld on Descartes]
Descartes is right that in the Christian view only God can guarantee the reliability of senses [Nietzsche on Descartes]
I know the truth that God exists and is the author of truth [Descartes]
Clear and distinct conceptions are true because a perfect God exists [Descartes]
Once it is clear that there is a God who is no deceiver, I conclude that clear and distinct perceptions must be true [Descartes]
3. Truth / A. Truth Problems / 2. Defining Truth
Truth is such a transcendentally clear notion that it cannot be further defined [Descartes]
3. Truth / A. Truth Problems / 8. Subjective Truth
Truth is clear and distinct conception - of which it is hard to be sure [Descartes]
My general rule is that everything that I perceive clearly and distinctly is true [Descartes]
Someone may think a thing is 'clear and distinct', but be wrong [Leibniz on Descartes]
3. Truth / D. Coherence Truth / 1. Coherence Truth
All items of possible human knowledge are interconnected, and can be reached by inference [Descartes]
4. Formal Logic / A. Syllogistic Logic / 2. Syllogistic Logic
Venn Diagrams map three predicates into eight compartments, then look for the conclusion [Bostock]
4. Formal Logic / B. Propositional Logic PL / 2. Tools of Propositional Logic / b. Terminology of PL
'Disjunctive Normal Form' is ensuring that no conjunction has a disjunction within its scope [Bostock]
'Conjunctive Normal Form' is ensuring that no disjunction has a conjunction within its scope [Bostock]
4. Formal Logic / B. Propositional Logic PL / 2. Tools of Propositional Logic / d. Basic theorems of PL
'Disjunction' says that Γ,φ∨ψ|= iff Γ,φ|= and Γ,ψ|= [Bostock]
'Assumptions' says that a formula entails itself (φ|=φ) [Bostock]
'Thinning' allows that if premisses entail a conclusion, then adding further premisses makes no difference [Bostock]
The 'conditional' is that Γ|=φ→ψ iff Γ,φ|=ψ [Bostock]
'Cutting' allows that if x is proved, and adding y then proves z, you can go straight to z [Bostock]
'Negation' says that Γ,¬φ|= iff Γ|=φ [Bostock]
'Conjunction' says that Γ|=φ∧ψ iff Γ|=φ and Γ|=ψ [Bostock]
4. Formal Logic / B. Propositional Logic PL / 2. Tools of Propositional Logic / e. Axioms of PL
A logic with ¬ and → needs three axiom-schemas and one rule as foundation [Bostock]
4. Formal Logic / E. Nonclassical Logics / 2. Intuitionist Logic
Classical interdefinitions of logical constants and quantifiers is impossible in intuitionism [Bostock]
4. Formal Logic / E. Nonclassical Logics / 6. Free Logic
A 'free' logic can have empty names, and a 'universally free' logic can have empty domains [Bostock]
4. Formal Logic / F. Set Theory ST / 1. Set Theory
There is no single agreed structure for set theory [Bostock]
4. Formal Logic / F. Set Theory ST / 3. Types of Set / a. Types of set
A 'proper class' cannot be a member of anything [Bostock]
4. Formal Logic / F. Set Theory ST / 4. Axioms for Sets / a. Axioms for sets
We could add axioms to make sets either as small or as large as possible [Bostock]
4. Formal Logic / F. Set Theory ST / 4. Axioms for Sets / j. Axiom of Choice IX
The Axiom of Choice relies on reference to sets that we are unable to describe [Bostock]
4. Formal Logic / F. Set Theory ST / 5. Conceptions of Set / f. Limitation of Size
Replacement enforces a 'limitation of size' test for the existence of sets [Bostock]
5. Theory of Logic / A. Overview of Logic / 5. First-Order Logic
First-order logic is not decidable: there is no test of whether any formula is valid [Bostock]
The completeness of first-order logic implies its compactness [Bostock]
5. Theory of Logic / A. Overview of Logic / 6. Classical Logic
Truth is the basic notion in classical logic [Bostock]
Elementary logic cannot distinguish clearly between the finite and the infinite [Bostock]
Fictional characters wreck elementary logic, as they have contradictions and no excluded middle [Bostock]
5. Theory of Logic / B. Logical Consequence / 3. Deductive Consequence |-
The syntactic turnstile |- φ means 'there is a proof of φ' or 'φ is a theorem' [Bostock]
5. Theory of Logic / B. Logical Consequence / 4. Semantic Consequence |=
Validity is a conclusion following for premises, even if there is no proof [Bostock]
It seems more natural to express |= as 'therefore', rather than 'entails' [Bostock]
Γ|=φ is 'entails'; Γ|= is 'is inconsistent'; |=φ is 'valid' [Bostock]
5. Theory of Logic / B. Logical Consequence / 5. Modus Ponens
MPP: 'If Γ|=φ and Γ|=φ→ψ then Γ|=ψ' (omit Γs for Detachment) [Bostock]
MPP is a converse of Deduction: If Γ |- φ→ψ then Γ,φ|-ψ [Bostock]
5. Theory of Logic / C. Ontology of Logic / 3. If-Thenism
Arithmetic and geometry achieve some certainty without worrying about existence [Descartes]
5. Theory of Logic / D. Assumptions for Logic / 4. Identity in Logic
|= α=α and α=β |= φ(α/ξ ↔ φ(β/ξ) fix identity [Bostock]
If we are to express that there at least two things, we need identity [Bostock]
The sign '=' is a two-place predicate expressing that 'a is the same thing as b' (a=b) [Bostock]
5. Theory of Logic / E. Structures of Logic / 2. Logical Connectives / a. Logical connectives
Truth-functors are usually held to be defined by their truth-tables [Bostock]
5. Theory of Logic / E. Structures of Logic / 5. Functions in Logic
A 'zero-place' function just has a single value, so it is a name [Bostock]
A 'total' function ranges over the whole domain, a 'partial' function over appropriate inputs [Bostock]
5. Theory of Logic / F. Referring in Logic / 1. Naming / a. Names
In logic, a name is just any expression which refers to a particular single object [Bostock]
5. Theory of Logic / F. Referring in Logic / 1. Naming / e. Empty names
An expression is only a name if it succeeds in referring to a real object [Bostock]
5. Theory of Logic / F. Referring in Logic / 2. Descriptions / b. Definite descriptions
Definite desciptions resemble names, but can't actually be names, if they don't always refer [Bostock]
Because of scope problems, definite descriptions are best treated as quantifiers [Bostock]
Definite descriptions are usually treated like names, and are just like them if they uniquely refer [Bostock]
We are only obliged to treat definite descriptions as non-names if only the former have scope [Bostock]
Definite descriptions don't always pick out one thing, as in denials of existence, or errors [Bostock]
5. Theory of Logic / F. Referring in Logic / 2. Descriptions / c. Theory of definite descriptions
Names do not have scope problems (e.g. in placing negation), but Russell's account does have that problem [Bostock]
5. Theory of Logic / G. Quantification / 1. Quantification
'Prenex normal form' is all quantifiers at the beginning, out of the scope of truth-functors [Bostock]
5. Theory of Logic / G. Quantification / 2. Domain of Quantification
If we allow empty domains, we must allow empty names [Bostock]
5. Theory of Logic / G. Quantification / 4. Substitutional Quantification
Substitutional quantification is just standard if all objects in the domain have a name [Bostock]
5. Theory of Logic / H. Proof Systems / 1. Proof Systems
An 'informal proof' is in no particular system, and uses obvious steps and some ordinary English [Bostock]
5. Theory of Logic / H. Proof Systems / 2. Axiomatic Proof
Quantification adds two axiom-schemas and a new rule [Bostock]
Axiom systems from Frege, Russell, Church, Lukasiewicz, Tarski, Nicod, Kleene, Quine... [Bostock]
5. Theory of Logic / H. Proof Systems / 3. Proof from Assumptions
'Conditonalised' inferences point to the Deduction Theorem: If Γ,φ|-ψ then Γ|-φ→ψ [Bostock]
Proof by Assumptions can always be reduced to Proof by Axioms, using the Deduction Theorem [Bostock]
The Deduction Theorem and Reductio can 'discharge' assumptions - they aren't needed for the new truth [Bostock]
The Deduction Theorem greatly simplifies the search for proof [Bostock]
5. Theory of Logic / H. Proof Systems / 4. Natural Deduction
The Deduction Theorem is what licenses a system of natural deduction [Bostock]
Natural deduction takes proof from assumptions (with its rules) as basic, and axioms play no part [Bostock]
Excluded middle is an introduction rule for negation, and ex falso quodlibet will eliminate it [Bostock]
In natural deduction we work from the premisses and the conclusion, hoping to meet in the middle [Bostock]
Natural deduction rules for → are the Deduction Theorem (→I) and Modus Ponens (→E) [Bostock]
5. Theory of Logic / H. Proof Systems / 5. Tableau Proof
Tableau proofs use reduction - seeking an impossible consequence from an assumption [Bostock]
A completed open branch gives an interpretation which verifies those formulae [Bostock]
Non-branching rules add lines, and branching rules need a split; a branch with a contradiction is 'closed' [Bostock]
In a tableau proof no sequence is established until the final branch is closed; hypotheses are explored [Bostock]
Unlike natural deduction, semantic tableaux have recipes for proving things [Bostock]
A tree proof becomes too broad if its only rule is Modus Ponens [Bostock]
Tableau rules are all elimination rules, gradually shortening formulae [Bostock]
5. Theory of Logic / H. Proof Systems / 6. Sequent Calculi
Each line of a sequent calculus is a conclusion of previous lines, each one explicitly recorded [Bostock]
A sequent calculus is good for comparing proof systems [Bostock]
5. Theory of Logic / I. Semantics of Logic / 1. Semantics of Logic
Interpretation by assigning objects to names, or assigning them to variables first [Bostock, by PG]
5. Theory of Logic / I. Semantics of Logic / 5. Extensionalism
Extensionality is built into ordinary logic semantics; names have objects, predicates have sets of objects [Bostock]
If an object has two names, truth is undisturbed if the names are swapped; this is Extensionality [Bostock]
5. Theory of Logic / K. Features of Logics / 2. Consistency
For 'negation-consistent', there is never |-(S)φ and |-(S)¬φ [Bostock]
A proof-system is 'absolutely consistent' iff we don't have |-(S)φ for every formula [Bostock]
A set of formulae is 'inconsistent' when there is no interpretation which can make them all true [Bostock]
5. Theory of Logic / K. Features of Logics / 6. Compactness
Inconsistency or entailment just from functors and quantifiers is finitely based, if compact [Bostock]
Compactness means an infinity of sequents on the left will add nothing new [Bostock]
5. Theory of Logic / L. Paradox / 4. Paradoxes in Logic / c. Berry's paradox
Berry's Paradox considers the meaning of 'The least number not named by this name' [Bostock]
6. Mathematics / A. Nature of Mathematics / 1. Mathematics
Surely maths is true even if I am dreaming? [Descartes]
I can learn the concepts of duration and number just from observing my own thoughts [Descartes]
6. Mathematics / A. Nature of Mathematics / 3. Nature of Numbers / b. Types of number
Each addition changes the ordinality but not the cardinality, prior to aleph-1 [Bostock]
ω + 1 is a new ordinal, but its cardinality is unchanged [Bostock]
6. Mathematics / A. Nature of Mathematics / 3. Nature of Numbers / c. Priority of numbers
A cardinal is the earliest ordinal that has that number of predecessors [Bostock]
6. Mathematics / A. Nature of Mathematics / 3. Nature of Numbers / f. Cardinal numbers
Aleph-1 is the first ordinal that exceeds aleph-0 [Bostock]
6. Mathematics / A. Nature of Mathematics / 3. Nature of Numbers / g. Real numbers
Instead of by cuts or series convergence, real numbers could be defined by axioms [Bostock]
The number of reals is the number of subsets of the natural numbers [Bostock]
Descartes showed a one-one order-preserving match between points on a line and the real numbers [Descartes, by Hart,WD]
6. Mathematics / A. Nature of Mathematics / 3. Nature of Numbers / i. Reals from cuts
For Eudoxus cuts in rationals are unique, but not every cut makes a real number [Bostock]
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 [Descartes]
I can only see the proportion of two to three if there is a common measure - their unity [Descartes]
6. Mathematics / A. Nature of Mathematics / 5. The Infinite / k. Infinitesimals
Infinitesimals are not actually contradictory, because they can be non-standard real numbers [Bostock]
6. Mathematics / B. Foundations for Mathematics / 3. Axioms for Geometry
Modern axioms of geometry do not need the real numbers [Bostock]
6. Mathematics / B. Foundations for Mathematics / 4. Axioms for Number / d. Peano arithmetic
The Peano Axioms describe a unique structure [Bostock]
6. Mathematics / B. Foundations for Mathematics / 4. Axioms for Number / f. Mathematical induction
Ordinary or mathematical induction assumes for the first, then always for the next, and hence for all [Bostock]
Complete induction assumes for all numbers less than n, then also for n, and hence for all numbers [Bostock]
6. Mathematics / B. Foundations for Mathematics / 5. Definitions of Number / d. Hume's Principle
Hume's Principle is a definition with existential claims, and won't explain numbers [Bostock]
Many things will satisfy Hume's Principle, so there are many interpretations of it [Bostock]
There are many criteria for the identity of numbers [Bostock]
6. Mathematics / B. Foundations for Mathematics / 5. Definitions of Number / e. Caesar problem
Frege makes numbers sets to solve the Caesar problem, but maybe Caesar is a set! [Bostock]
6. Mathematics / B. Foundations for Mathematics / 7. Mathematical Structuralism / e. Structuralism critique
Numbers can't be positions, if nothing decides what position a given number has [Bostock]
Structuralism falsely assumes relations to other numbers are numbers' only properties [Bostock]
6. Mathematics / C. Sources of Mathematics / 3. Mathematical Nominalism
Nominalism about mathematics is either reductionist, or fictionalist [Bostock]
Nominalism as based on application of numbers is no good, because there are too many applications [Bostock]
6. Mathematics / C. Sources of Mathematics / 4. Mathematical Empiricism / b. Indispensability of mathematics
Actual measurement could never require the precision of the real numbers [Bostock]
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 [Descartes]
6. Mathematics / C. Sources of Mathematics / 5. Numbers as Adjectival
Ordinals are mainly used adjectively, as in 'the first', 'the second'... [Bostock]
6. Mathematics / C. Sources of Mathematics / 6. Logicism / b. Type theory
Simple type theory has 'levels', but ramified type theory has 'orders' [Bostock]
6. Mathematics / C. Sources of Mathematics / 6. Logicism / c. Neo-logicism
Neo-logicists agree that HP introduces number, but also claim that it suffices for the job [Bostock]
Neo-logicists meet the Caesar problem by saying Hume's Principle is unique to number [Bostock]
6. Mathematics / C. Sources of Mathematics / 6. Logicism / d. Logicism critique
If Hume's Principle is the whole story, that implies structuralism [Bostock]
Many crucial logicist definitions are in fact impredicative [Bostock]
Treating numbers as objects doesn't seem like logic, since arithmetic fixes their totality [Bostock]
6. Mathematics / C. Sources of Mathematics / 9. Fictional Mathematics
Higher cardinalities in sets are just fairy stories [Bostock]
A fairy tale may give predictions, but only a true theory can give explanations [Bostock]
6. Mathematics / C. Sources of Mathematics / 10. Constructivism / c. Conceptualism
The best version of conceptualism is predicativism [Bostock]
Conceptualism fails to grasp mathematical properties, infinity, and objective truth values [Bostock]
6. Mathematics / C. Sources of Mathematics / 10. Constructivism / d. Predicativism
If abstracta only exist if they are expressible, there can only be denumerably many of them [Bostock]
Predicativism makes theories of huge cardinals impossible [Bostock]
If mathematics rests on science, predicativism may be the best approach [Bostock]
If we can only think of what we can describe, predicativism may be implied [Bostock]
The predicativity restriction makes a difference with the real numbers [Bostock]
The usual definitions of identity and of natural numbers are impredicative [Bostock]
7. Existence / A. Nature of Existence / 3. Being / d. Non-being
Among the simples are the graspable negations, such as rest and instants [Descartes]
7. Existence / C. Structure of Existence / 5. Supervenience / c. Significance of supervenience
Two things being joined together doesn't prove they are the same [Descartes]
8. Modes of Existence / A. Relations / 4. Formal Relations / a. Types of relation
A relation is not reflexive, just because it is transitive and symmetrical [Bostock]
Relations can be one-many (at most one on the left) or many-one (at most one on the right) [Bostock]
8. Modes of Existence / C. Powers and Dispositions / 2. Powers as Basic
Incorporeal substances are powers or forces [Descartes, by 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 [Descartes]
8. Modes of Existence / D. Universals / 1. Universals
Five universals: genus, species, difference, property, accident [Descartes]
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 [Descartes]
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 [Descartes]
9. Objects / B. Unity of Objects / 2. Substance / a. Substance
Knowing the attributes is enough to reveal a substance [Descartes]
If we perceive an attribute, we infer the existence of some substance [Descartes]
9. Objects / B. Unity of Objects / 2. Substance / d. Substance defined
A substance needs nothing else in order to exist [Descartes]
9. Objects / B. Unity of Objects / 2. Substance / e. Substance critique
Substance cannot be conceived or explained to others [Gassendi on Descartes]
Descartes thinks distinguishing substances from aggregates is pointless [Descartes, by Pasnau]
9. Objects / C. Structure of Objects / 7. Substratum
If we remove surface qualities from wax, we have an extended, flexible, changeable thing [Descartes]
9. Objects / D. Essence of Objects / 4. Essence as Definition
Descartes gives an essence by an encapsulating formula [Descartes, by Almog]
9. Objects / D. Essence of Objects / 9. Essence and Properties
A substance has one principal property which is its nature and essence [Descartes]
9. Objects / D. Essence of Objects / 15. Against Essentialism
Substantial forms are not understood, and explain nothing [Descartes]
9. Objects / F. Identity among Objects / 5. Self-Identity
If non-existent things are self-identical, they are just one thing - so call it the 'null object' [Bostock]
10. Modality / A. Necessity / 6. Logical Necessity
The idea that anything which can be proved is necessary has a problem with empty names [Bostock]
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 [Descartes]
10. Modality / D. Knowledge of Modality / 1. A Priori Necessary
We know by thought that what is done cannot be undone [Descartes]
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 on Descartes]
11. Knowledge Aims / A. Knowledge / 4. Belief / a. Beliefs
We can believe a thing without knowing we believe it [Descartes]
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 [Descartes, by Zagzebski]
11. Knowledge Aims / B. Certain Knowledge / 1. Certainty
If we accept mere probabilities as true we undermine our existing knowledge [Descartes]
In pursuing truth, anything less certain than mathematics is a waste of time [Descartes]
In morals Descartes accepts the conventional, but rejects it in epistemology [Roochnik on Descartes]
Descartes tried to model reason on maths instead of 'logos' [Roochnik on Descartes]
Labelling slightly doubtful things as false is irrational [Roochnik on Descartes]
Maybe there is only one certain fact, which is that nothing is certain [Descartes]
Understanding, not the senses, gives certainty [Descartes]
11. Knowledge Aims / B. Certain Knowledge / 4. The Cogito
If I don't think, there is no reason to think that I exist [Descartes]
Total doubt can't include your existence while doubting [Descartes]
Descartes transformed 'God is thinkable, so he exists' into 'I think, so I exist' [Descartes, by Feuerbach]
In the Meditations version of the Cogito he says "I am; I exist", which avoids presenting it as an argument [Descartes, by Baggini /Fosl]
I think, therefore I am, because for a thinking thing to not exist is a contradiction [Descartes]
'Thought' is all our conscious awareness, including feeling as well as understanding [Descartes]
The Cogito is not a syllogism but a self-evident intuition [Descartes]
We all see intuitively that we exist, where intuition is attentive, clear and distinct rational understanding [Descartes]
When Socrates doubts, he know he doubts, and that truth is possible [Descartes]
Modern philosophy set the self-conscious ego in place of God [Descartes, by Feuerbach]
"I think therefore I am" is the absolute truth of consciousness [Sartre on Descartes]
I must even exist if I am being deceived by something [Descartes]
"I am, I exist" is necessarily true every time I utter it or conceive it in my mind [Descartes]
The Cogito is a transcendental argument, not a piece of a priori knowledge [Rey on Descartes]
In thinking everything else false, my own existence remains totally certain [Descartes]
11. Knowledge Aims / B. Certain Knowledge / 5. Cogito Critique
The Cogito only works if you already understand what thought and existence are [Mersenne on Descartes]
It is a precondition of the use of the word 'I' that I exist [Ayer on Descartes]
The thing which experiences may be momentary, and change with the next experience [Russell on Descartes]
'I think' assumes I exist, that thinking is known and caused, and that I am doing it [Nietzsche on Descartes]
A thought doesn't imply other thoughts, or enough thoughts to make up a self [Ayer on Descartes]
That I perform an activity (thinking) doesn't prove what type of thing I am [Hobbes on Descartes]
Autistic children seem to use the 'I' concept without seeing themselves as thinkers [Segal on Descartes]
The Cogito assumes a priori the existence of substance, when actually it is a grammatical custom [Nietzsche on Descartes]
How can we infer that all thinking involves self-consciousness, just from my own case? [Kant on Descartes]
My self is not an inference from 'I think', but a presupposition of it [Kant on Descartes]
We cannot give any information a priori about the nature of the 'thing that thinks' [Kant on Descartes]
The fact that I am a subject is not enough evidence to show that I am a substantial object [Kant on Descartes]
Descartes' claim to know his existence before his essence is misleading or absurd [Descartes, by Lowe]
Modern self-consciousness is a doubtful abstraction; only senses and feelings are certain [Feuerbach on Descartes]
The Cogito proves subjective experience is basic, but makes false claims about the Self [Russell on Descartes]
Maybe 'I' am not the thinker, but something produced by thought [Nietzsche on Descartes]
11. Knowledge Aims / C. Knowing Reality / 2. Phenomenalism
My perceiving of things may be false, but my seeming to perceive them cannot be false [Descartes]
11. Knowledge Aims / C. Knowing Reality / 4. Solipsism
I myself could be the author of all these self-delusions [Descartes]
12. Knowledge Sources / A. A Priori Knowledge / 2. Self-Evidence
Clear and distinct truths must be known all at once (unlike deductions) [Descartes]
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 [Descartes]
Our thinking about external things doesn't disprove the existence of innate ideas [Descartes]
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 [Descartes]
'Nothing comes from nothing' is an eternal truth found within the mind [Descartes]
What experience could prove 'If a=c and b=c then a=b'? [Descartes]
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 [Descartes]
12. Knowledge Sources / B. Perception / 2. Qualities in Perception / c. Primary qualities
For Descartes, objects have one primary quality, which is geometrical [Descartes, by 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 [Descartes]
12. Knowledge Sources / B. Perception / 3. Representation
Descartes said images can refer to objects without resembling them (as words do) [Descartes, by Tuck]
12. Knowledge Sources / B. Perception / 5. Interpretation
Why does pain make us sad? [Descartes]
12. Knowledge Sources / C. Rationalism / 1. Rationalism
Dogs can make the same judgements as us about variable things [Gassendi on Descartes]
We perceive objects by intellect, not by senses or imagination [Descartes]
Understanding, rather than imagination or senses, gives knowledge [Descartes]
The wax is not perceived by the senses, but by the mind alone [Descartes]
We don't 'see' men in heavy clothes, we judge them to be men [Descartes]
12. Knowledge Sources / D. Empiricism / 5. Empiricism Critique
If someone had only seen the basic colours, they could deduce the others from resemblance [Descartes]
13. Knowledge Criteria / B. Internal Justification / 4. Foundationalism / a. Foundationalism
The method starts with clear intuitions, followed by a process of deduction [Descartes]
I was searching for reliable rock under the shifting sand [Descartes]
To achieve good science we must rebuild from the foundations [Descartes]
Only one certainty is needed for progress (like a lever's fulcrum) [Descartes]
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 [Descartes]
13. Knowledge Criteria / D. Scepticism / 1. Scepticism
Even if my body and objects are imaginary, there may be simpler things which are true [Descartes]
Descartes can't begin again, because sceptics doubt cognitive processes as well as beliefs [Pollock/Cruz on Descartes]
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 [Descartes]
We correct sense errors with other senses, not intellect [Mersenne on Descartes]
The senses can only report, so perception errors are in the judgment [Gassendi on Descartes]
It is prudent never to trust your senses if they have deceived you even once [Descartes]
Only judgement decides which of our senses are reliable [Descartes]
13. Knowledge Criteria / D. Scepticism / 4. Demon Scepticism
God may have created nothing, but made his creation appear to me as it does now [Descartes]
To achieve full scepticism, I imagine a devil who deceives me about the external world and my own body and senses [Descartes]
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 [Descartes]
13. Knowledge Criteria / D. Scepticism / 6. Scepticism Critique
When rebuilding a house, one needs alternative lodgings [Descartes]
I can only sense an object if it is present, and can't fail to sense it when it is [Descartes]
14. Science / A. Basis of Science / 3. Experiment
Only experiments can settle disagreements between rival explanations [Descartes]
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 on Descartes]
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 on Descartes]
15. Nature of Minds / A. Nature of Mind / 5. Unity of Mind
Faculties of the mind aren't parts, as one mind uses them [Descartes]
15. Nature of Minds / A. Nature of Mind / 7. Animal Minds
Little reason is needed to speak, so animals have no reason at all [Descartes]
15. Nature of Minds / A. Nature of Mind / 8. Brain
Nerves and movement originate in the brain, where imagination moves them [Descartes]
15. Nature of Minds / B. Features of Minds / 1. Consciousness / b. Essence of consciousness
We can understand thinking occuring without imagination or sensation [Descartes]
15. Nature of Minds / B. Features of Minds / 2. Unconscious Mind
I can't be unaware of anything which is in me [Descartes]
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 on Descartes]
15. Nature of Minds / C. Capacities of Minds / 1. Faculties
Our four knowledge faculties are intelligence, imagination, the senses, and memory [Descartes]
Descartes mentions many cognitive faculties, but reduces them to will and intellect [Descartes, by Schmid]
15. Nature of Minds / C. Capacities of Minds / 2. Imagination
Imagination and sensation are non-essential to mind [Descartes]
16. Persons / A. Concept of a Person / 1. Existence of Persons
Some cause must unite the separate temporal sections of a person [Descartes]
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 [Descartes]
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 [Descartes]
I can exist without imagination and sensing, but they can't exist without me [Descartes]
For Descartes a person's essence is the mind because objects are perceived by mind, not senses [Descartes, by Feuerbach]
In thinking we shut ourselves off from other substances, showing our identity and separateness [Descartes]
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 [Descartes]
Our free will is so self-evident to us that it must be a basic innate idea [Descartes]
16. Persons / F. Free Will / 3. Constraints on the will
The more reasons that compel me, the freer I am [Descartes]
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 [Descartes]
We have inner awareness of our freedom [Descartes]
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 [Descartes]
I can deny my body and the world, but not my own existence [Descartes]
Reason is universal in its responses, but a physical machine is constrained by its organs [Descartes]
The mind is a non-extended thing which thinks [Descartes]
Mind is not extended, unlike the body [Descartes]
Descartes is a substance AND property dualist [Descartes, by Kim]
The mind is utterly indivisible [Descartes]
There are two ultimate classes of existence: thinking substance and extended substance [Descartes]
17. Mind and Body / A. Mind-Body Dualism / 2. Interactionism
The soul must unite with the body to have appetites and sensations [Descartes]
Interaction between mental and physical seems to violate the principle of conservation of energy [Rowlands on Descartes]
Descartes discussed the interaction problem, and compared it with gravity [Descartes, by Lycan]
The pineal gland links soul to body, and unites the two symmetrical sides of the body [Descartes, by 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 on Descartes]
Knowing different aspects of brain/mind doesn't make them different [Rorty on Descartes]
Descartes gives no clear criterion for individuating mental substances [Cottingham on Descartes]
Does Descartes have a clear conception of how mind unites with body? [Spinoza on Descartes]
Even Descartes may concede that mental supervenes on neuroanatomical [Lycan on Descartes]
Superman's strength is indubitable, Clark Kent's is doubtful, so they are not the same? [Maslin on Descartes]
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 [Descartes]
17. Mind and Body / E. Mind as Physical / 6. Conceptual Dualism
The concept of mind excludes body, and vice versa [Descartes]
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 [Descartes]
18. Thought / A. Modes of Thought / 3. Emotions / c. Role of emotions
For Descartes passions are God-given preservers of the mind-body union [Descartes, by Taylor,C]
18. Thought / A. Modes of Thought / 3. Emotions / e. Basic emotions
Are there a few primary passions (say, joy, sadness and desire)? [Descartes, by Cottingham]
There are six primitive passions: wonder, love, hatred, desire, joy and sadness [Descartes, by 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 [Descartes, by Taylor,C]
18. Thought / A. Modes of Thought / 6. Judgement / b. Error
I make errors because my will extends beyond my understanding [Descartes]
Most errors of judgement result from an inaccurate perception of the facts [Descartes]
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 [Descartes]
18. Thought / C. Content / 2. Ideas
True ideas are images, such as of a man, a chimera, or God [Descartes]
18. Thought / C. Content / 10. Causal Semantics
All ideas are adventitious, and come from the senses [Gassendi on Descartes]
18. Thought / D. Concepts / 2. Origin of Concepts / c. Nativist concepts
A blind man may still contain the idea of colour [Descartes]
The mind's innate ideas are part of its capacity for thought [Descartes]
The ideas of God and of my self are innate in me [Descartes]
I can think of innumerable shapes I have never experienced [Descartes]
Qualia must be innate, because physical motions do not contain them [Descartes]
The idea of a supremely perfect being is within me, like the basic concepts of mathematics [Descartes]
19. Language / C. Assigning Meanings / 3. Predicates
A (modern) predicate is the result of leaving a gap for the name in a sentence [Bostock]
19. Language / F. Communication / 2. Assertion
In logic a proposition means the same when it is and when it is not asserted [Bostock]
20. Action / B. Preliminaries of Action / 2. Willed Action / b. Volitionism
Merely willing to walk leads to our walking [Descartes]
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 [Descartes]
The greatest perfection of man is to act by free will, and thus merit praise or blame [Descartes]
22. Metaethics / B. Value / 2. Values / e. Death
We don't die because the soul departs; the soul departs because the organs cease functioning [Descartes]
23. Ethics / C. Virtue Theory / 1. Virtue Theory / d. Virtue theory critique
Greeks elevate virtues enormously, but never explain them [Descartes]
23. Ethics / C. Virtue Theory / 3. Virtues / a. Virtues
Descartes makes strength of will the central virtue [Descartes, by Taylor,C]
23. Ethics / F. Existentialism / 5. Existence-Essence
Essence must be known before we discuss existence [Descartes]
25. Social Practice / F. Life Issues / 6. Animal Rights
Animals are dangerous and nourishing, and can't form contracts of justice [Hermarchus, by Sedley]
26. Natural Theory / A. Speculations on Nature / 1. Nature
Nature is devoid of thought [Descartes, by Meillassoux]
Physics only needs geometry or abstract mathematics, which can explain and demonstrate everything [Descartes]
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 [Descartes]
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 [Descartes]
26. Natural Theory / A. Speculations on Nature / 4. Mathematical Nature
All the sciences searching for order and measure are related to mathematics [Descartes]
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 [Descartes]
26. Natural Theory / A. Speculations on Nature / 7. Later Matter Theories / c. Matter as extension
Impenetrability only belongs to the essence of extension [Descartes]
Matter can't just be Descartes's geometry, because a filler of the spaces is needed [Robinson,H on Descartes]
Matter is not hard, heavy or coloured, but merely extended in space [Descartes]
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 [Descartes]
26. Natural Theory / D. Laws of Nature / 7. Strictness of Laws
God has established laws throughout nature, and implanted ideas of them within us [Descartes]
27. Natural Reality / A. Classical Physics / 1. Mechanics / b. Laws of motion
Descartes said there was conservation of 'quantity of motion' [Descartes, by Papineau]
28. God / A. Divine Nature / 2. Divine Nature
God the creator is an intelligent, infinite, powerful substance [Descartes]
Nothing apart from God could have essential existence, and such a being must be unique and eternal [Descartes]
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 [Descartes]
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 [Descartes]
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 [Descartes]
One idea leads to another, but there must be an initial idea that contains the reality of all the others [Descartes]
Possible existence is a perfection in the idea of a triangle [Descartes]
The idea of God in my mind is like the mark a craftsman puts on his work [Descartes]
Necessary existence is a property which is uniquely part of God's essence [Descartes]
I cannot think of a supremely perfect being without the supreme perfection of existence [Descartes]
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 on Descartes]
We can never conceive of an infinite being [Gassendi on Descartes]
Descartes cannot assume that a most perfect being exists without contradictions [Leibniz on Descartes]
Existence is not a perfection; it is what makes perfection possible [Gassendi on Descartes]
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 [Descartes]
28. God / C. Attitudes to God / 5. Atheism
Atheism is an atrocious and intolerable crime in any country [Descartes]
Atheism arises from empiricism, because God is intangible [Descartes]
29. Religion / B. Monotheistic Religion / 4. Christianity / c. Angels
An angelic mind would not experience pain, even when connected to a human body [Descartes, by 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 [Descartes]
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 on Descartes]
Error arises because my faculty for judging truth is not infinite [Descartes]
Since God does not wish to deceive me, my judgement won't make errors if I use it properly [Descartes]
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 [Descartes]