Combining Philosophers

All the ideas for David Bostock, Baruch de Spinoza and George Boolos

expand these ideas     |    start again     |     specify just one area for these philosophers


372 ideas

1. Philosophy / A. Wisdom / 1. Nature of Wisdom
The wisdom of a free man is a meditation on life, not on death [Spinoza]
If we are not wholly wise, we should live by good rules and maxims [Spinoza]
1. Philosophy / F. Analytic Philosophy / 5. Linguistic Analysis
We must be careful to keep words distinct from ideas and images [Spinoza]
2. Reason / A. Nature of Reason / 3. Pure Reason
Reason only explains what is universal, so it is timeless, under a certain form of eternity [Spinoza]
Reason perceives things under a certain form of eternity [Spinoza]
2. Reason / A. Nature of Reason / 4. Aims of Reason
Without reason and human help, human life is misery [Spinoza]
In so far as men live according to reason, they will agree with one another [Spinoza]
2. Reason / B. Laws of Thought / 2. Sufficient Reason
There is necessarily for each existent thing a cause why it should exist [Spinoza]
2. Reason / D. Definition / 2. Aims of Definition
All the intrinsic properties of a thing should be deducible from its definition [Spinoza]
2. Reason / D. Definition / 8. Impredicative Definition
Impredicative definitions are wrong, because they change the set that is being defined? [Bostock]
3. Truth / A. Truth Problems / 1. Truth
Truth is its own standard [Spinoza]
3. Truth / A. Truth Problems / 3. Value of Truth
Spinoza's life shows that love of truth which he proclaims as the highest value [MacIntyre on Spinoza]
3. Truth / A. Truth Problems / 8. Subjective Truth
For Spinoza, 'adequacy' is the intrinsic mark of truth [Spinoza, by Scruton]
3. Truth / C. Correspondence Truth / 1. Correspondence Truth
A true idea must correspond with its ideate or object [Spinoza]
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
'Conjunctive Normal Form' is ensuring that no disjunction has a conjunction within its scope [Bostock]
'Disjunctive Normal Form' is ensuring that no conjunction has a disjunction 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
The logic of ZF is classical first-order predicate logic with identity [Boolos]
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
A few axioms of set theory 'force themselves on us', but most of them don't [Boolos]
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 / h. Axiom of Replacement VII
Do the Replacement Axioms exceed the iterative conception of sets? [Boolos, by Maddy]
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 / a. Sets as existing
The use of plurals doesn't commit us to sets; there do not exist individuals and collections [Boolos]
4. Formal Logic / F. Set Theory ST / 5. Conceptions of Set / d. Naïve logical sets
Naïve sets are inconsistent: there is no set for things that do not belong to themselves [Boolos]
4. Formal Logic / F. Set Theory ST / 5. Conceptions of Set / e. Iterative sets
The iterative conception says sets are formed at stages; some are 'earlier', and must be formed first [Boolos]
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]
Limitation of Size is weak (Fs only collect is something the same size does) or strong (fewer Fs than objects) [Boolos, by Potter]
4. Formal Logic / F. Set Theory ST / 8. Critique of Set Theory
Does a bowl of Cheerios contain all its sets and subsets? [Boolos]
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 / A. Overview of Logic / 7. Second-Order Logic
Boolos reinterprets second-order logic as plural logic [Boolos, by Oliver/Smiley]
Monadic second-order logic might be understood in terms of plural quantifiers [Boolos, by Shapiro]
Second-order logic metatheory is set-theoretic, and second-order validity has set-theoretic problems [Boolos]
Boolos showed how plural quantifiers can interpret monadic second-order logic [Boolos, by Linnebo]
Any sentence of monadic second-order logic can be translated into plural first-order logic [Boolos, by Linnebo]
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
If our ideas are adequate, what follows from them is also adequate [Spinoza]
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 / 1. Ontology of Logic
A sentence can't be a truth of logic if it asserts the existence of certain sets [Boolos]
5. Theory of Logic / D. Assumptions for Logic / 4. Identity in Logic
Identity is clearly a logical concept, and greatly enhances predicate calculus [Boolos]
|= 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 descriptions don't always pick out one thing, as in denials of existence, or errors [Bostock]
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]
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]
'∀x x=x' only means 'everything is identical to itself' if the range of 'everything' is fixed [Boolos]
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 / G. Quantification / 5. Second-Order Quantification
Second-order quantifiers are just like plural quantifiers in ordinary language, with no extra ontology [Boolos, by Shapiro]
5. Theory of Logic / G. Quantification / 6. Plural Quantification
We should understand second-order existential quantifiers as plural quantifiers [Boolos, by Shapiro]
Plural forms have no more ontological commitment than to first-order objects [Boolos]
5. Theory of Logic / G. Quantification / 7. Unorthodox Quantification
Boolos invented plural quantification [Boolos, by Benardete,JA]
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]
The Deduction Theorem greatly simplifies the search for proof [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]
5. Theory of Logic / H. Proof Systems / 4. Natural Deduction
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]
The Deduction Theorem is what licenses a system of natural deduction [Bostock]
5. Theory of Logic / H. Proof Systems / 5. Tableau Proof
A tree proof becomes too broad if its only rule is Modus Ponens [Bostock]
Tableau rules are all elimination rules, gradually shortening formulae [Bostock]
Unlike natural deduction, semantic tableaux have recipes for proving things [Bostock]
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]
5. Theory of Logic / H. Proof Systems / 6. Sequent Calculi
A sequent calculus is good for comparing proof systems [Bostock]
Each line of a sequent calculus is a conclusion of previous lines, each one explicitly recorded [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 / 4. Completeness
Weak completeness: if it is valid, it is provable. Strong: it is provable from a set of sentences [Boolos]
5. Theory of Logic / K. Features of Logics / 6. Compactness
Why should compactness be definitive of logic? [Boolos, by Hacking]
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
Mathematics deals with the essences and properties of forms [Spinoza]
6. Mathematics / A. Nature of Mathematics / 2. Geometry
The sum of its angles follows from a triangle's nature [Spinoza]
The idea of a triangle involves truths about it, so those are part of its essence [Spinoza]
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]
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 / 5. The Infinite / a. The Infinite
Infinite natural numbers is as obvious as infinite sentences in English [Boolos]
6. Mathematics / A. Nature of Mathematics / 5. The Infinite / f. Uncountable infinities
Mathematics and science do not require very high orders of infinity [Boolos]
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 / e. Peano arithmetic 2nd-order
Many concepts can only be expressed by second-order logic [Boolos]
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 / 1. Mathematical Platonism / a. For mathematical platonism
Mathematics isn't surprising, given that we experience many objects as abstract [Boolos]
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 / 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 usual definitions of identity and of natural numbers are impredicative [Bostock]
The predicativity restriction makes a difference with the real numbers [Bostock]
7. Existence / A. Nature of Existence / 2. Types of Existence
Outside the mind, there are just things and their properties [Spinoza]
The more reality a thing has, the more attributes it has [Spinoza]
7. Existence / A. Nature of Existence / 5. Reason for Existence
There must always be a reason or cause why some triangle does or does not exist [Spinoza]
7. Existence / C. Structure of Existence / 1. Grounding / a. Nature of grounding
Men say they prefer order, not realising that we imagine the order [Spinoza]
7. Existence / D. Theories of Reality / 5. Naturalism
Laws of nature are universal, so everything must be understood through those laws [Spinoza]
7. Existence / D. Theories of Reality / 11. Ontological Commitment / b. Commitment of quantifiers
First- and second-order quantifiers are two ways of referring to the same things [Boolos]
8. Modes of Existence / A. Relations / 4. Formal Relations / a. Types of relation
Relations can be one-many (at most one on the left) or many-one (at most one on the right) [Bostock]
A relation is not reflexive, just because it is transitive and symmetrical [Bostock]
8. Modes of Existence / B. Properties / 3. Types of Properties
An 'attribute' is what the intellect takes as constituting an essence [Spinoza]
8. Modes of Existence / B. Properties / 8. Properties as Modes
A 'mode' is an aspect of a substance, and conceived through that substance [Spinoza]
8. Modes of Existence / C. Powers and Dispositions / 2. Powers as Basic
Things persevere through a force which derives from God [Spinoza]
8. Modes of Existence / C. Powers and Dispositions / 4. Powers as Essence
The essence of a thing is its effort to persevere [Spinoza]
8. Modes of Existence / D. Universals / 1. Universals
It is lunacy to think we only see ink-marks, and not word-types [Boolos]
8. Modes of Existence / D. Universals / 6. Platonic Forms / d. Forms critiques
The 'universal' term 'man' is just imagining whatever is the same in a multitude of men [Spinoza]
9. Objects / A. Existence of Objects / 2. Abstract Objects / a. Nature of abstracta
I am a fan of abstract objects, and confident of their existence [Boolos]
9. Objects / A. Existence of Objects / 2. Abstract Objects / c. Modern abstracta
We deal with abstract objects all the time: software, poems, mistakes, triangles.. [Boolos]
9. Objects / B. Unity of Objects / 1. Unifying an Object / b. Unifying aggregates
A thing is unified if its parts produce a single effect [Spinoza]
9. Objects / B. Unity of Objects / 2. Substance / b. Need for substance
Spinoza implies that thought is impossible without the notion of substance [Spinoza, by Scruton]
9. Objects / B. Unity of Objects / 2. Substance / d. Substance defined
Substance is the power of self-actualisation [Spinoza, by Lord]
Substance is that of which an independent conception can be formed [Spinoza]
9. Objects / D. Essence of Objects / 1. Essences of Objects
The essence of a thing is what is required for it to exist or be conceived [Spinoza]
9. Objects / D. Essence of Objects / 6. Essence as Unifier
Essence gives existence and conception to things, and is inseparable from them [Spinoza]
9. Objects / D. Essence of Objects / 7. Essence and Necessity / b. Essence not necessities
Nothing is essential if it is in every part, and is common to everything [Spinoza]
9. Objects / D. Essence of Objects / 8. Essence as Explanatory
All natures of things produce some effect [Spinoza]
9. Objects / D. Essence of Objects / 14. Knowledge of Essences
Experience does not teach us any essences of things [Spinoza]
9. Objects / E. Objects over Time / 11. End of an Object
Only an external cause can destroy something [Spinoza]
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]
9. Objects / F. Identity among Objects / 7. Indiscernible Objects
There cannot be two substances with the same attributes [Spinoza]
9. Objects / F. Identity among Objects / 8. Leibniz's Law
Two substances can't be the same if they have different attributes [Spinoza]
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 / A. Necessity / 10. Impossibility
Things are impossible if they imply contradiction, or their production lacks an external cause [Spinoza]
10. Modality / B. Possibility / 5. Contingency
Contingency is an illusion, resulting from our inadequate understanding [Spinoza, by Cottingham]
We only call things 'contingent' in relation to the imperfection of our knowledge [Spinoza]
Reason naturally regards things as necessary, and only imagination considers them contingent [Spinoza]
10. Modality / C. Sources of Modality / 1. Sources of Necessity
Divine nature makes all existence and operations necessary, and nothing is contingent [Spinoza]
10. Modality / C. Sources of Modality / 6. Necessity from Essence
Necessity is in reference to essence or to cause [Spinoza]
10. Modality / D. Knowledge of Modality / 4. Conceivable as Possible / a. Conceivable as possible
People who are ignorant of true causes imagine anything can change into anything else [Spinoza]
Error does not result from imagining, but from lacking the evidence of impossibility [Spinoza]
10. Modality / E. Possible worlds / 3. Transworld Objects / a. Transworld identity
A horse would be destroyed if it were changed into a man or an insect [Spinoza]
10. Modality / E. Possible worlds / 3. Transworld Objects / e. Possible Objects
A thing is contingent if nothing in its essence determines whether or not it exists [Spinoza]
11. Knowledge Aims / A. Knowledge / 1. Knowledge
Spinoza's three levels of knowledge are perception/imagination, then principles, then intuitions [Spinoza, by Scruton]
11. Knowledge Aims / A. Knowledge / 2. Understanding
Understanding is the sole aim of reason, and the only profit for the mind [Spinoza]
11. Knowledge Aims / A. Knowledge / 4. Belief / e. Belief holism
Unlike Descartes' atomism, Spinoza held a holistic view of belief [Spinoza, by Schmid]
11. Knowledge Aims / B. Certain Knowledge / 1. Certainty
True ideas intrinsically involve the highest degree of certainty [Spinoza]
You only know you are certain of something when you actually are certain of it [Spinoza]
A man who assents without doubt to a falsehood is not certain, but lacks a cause to make him waver [Spinoza]
11. Knowledge Aims / B. Certain Knowledge / 5. Cogito Critique
'I think' is useless, because it is contingent, and limited to the first person [Spinoza, by Scruton]
12. Knowledge Sources / B. Perception / 5. Interpretation
If the body is affected by an external object, the mind can't help believing that the object exists [Spinoza]
12. Knowledge Sources / C. Rationalism / 1. Rationalism
The eyes of the mind are proofs [Spinoza]
12. Knowledge Sources / D. Empiricism / 2. Associationism
Once we have experienced two feelings together, one will always give rise to the other [Spinoza]
13. Knowledge Criteria / A. Justification Problems / 3. Internal or External / a. Pro-internalism
Anyone who knows, must know that they know, and even know that they know that they know.. [Spinoza]
13. Knowledge Criteria / B. Internal Justification / 5. Coherentism / b. Pro-coherentism
Encounters with things confuse the mind, and internal comparisons bring clarity [Spinoza]
14. Science / D. Explanation / 2. Types of Explanation / f. Necessity in explanations
To understand a phenomenon, we must understand why it is necessary, not merely contingent [Spinoza, by Cottingham]
14. Science / D. Explanation / 2. Types of Explanation / k. Explanations by essence
To understand the properties we must know the essence, as with a circle [Spinoza]
15. Nature of Minds / A. Nature of Mind / 1. Mind / a. Mind
The human mind is the very idea or knowledge of the human body [Spinoza]
15. Nature of Minds / A. Nature of Mind / 1. Mind / b. Purpose of mind
Knowledge is the essence of the mind [Spinoza]
15. Nature of Minds / A. Nature of Mind / 1. Mind / c. Features of mind
Will and intellect are the same thing [Spinoza]
The will is finite, but the intellect is infinite [Spinoza]
The will is not a desire, but the faculty of affirming what is true or false [Spinoza]
15. Nature of Minds / A. Nature of Mind / 5. Unity of Mind
Spinoza held that the mind is just a bundle of ideas [Spinoza, by Schmid]
15. Nature of Minds / A. Nature of Mind / 7. Animal Minds
Animals are often observed to be wiser than people [Spinoza]
15. Nature of Minds / B. Features of Minds / 1. Consciousness / d. Purpose of consciousness
To understand is the absolute virtue of the mind [Spinoza]
15. Nature of Minds / C. Capacities of Minds / 1. Faculties
Faculties are either fictions, or the abstract universals of ideas [Spinoza]
15. Nature of Minds / C. Capacities of Minds / 8. Remembering Contiguity
If the body is affected by two things together, the imagining of one will conjure up the other [Spinoza]
15. Nature of Minds / C. Capacities of Minds / 10. Conatus/Striving
Our own force of persevering is nothing in comparison with external forces [Spinoza]
As far as possible, everything tries to persevere [Spinoza]
The conatus (striving) of mind and body together is appetite, which is the essence of man [Spinoza]
16. Persons / B. Nature of the Self / 7. Self and Body / a. Self needs body
The mind only knows itself by means of ideas of the modification of the body [Spinoza]
16. Persons / C. Self-Awareness / 2. Knowing the Self
Self-knowledge needs perception of the affections of the body [Spinoza]
16. Persons / D. Continuity of the Self / 2. Mental Continuity / a. Memory is Self
The poet who forgot his own tragedies was no longer the same man [Spinoza]
16. Persons / F. Free Will / 1. Nature of Free Will
A thing is free if it acts by necessity of its own nature, and the act is determined by itself alone [Spinoza]
16. Persons / F. Free Will / 2. Sources of Free Will
People are only free if they are guided entirely by reason [Spinoza]
16. Persons / F. Free Will / 5. Against Free Will
A thing is free if it acts only by the necessity of its own nature [Spinoza]
An act of will can only occur if it has been caused, which implies a regress of causes [Spinoza]
'Free will' is a misunderstanding arising from awareness of our actions, but ignorance of their causes [Spinoza]
Would we die if we lacked free will, and were poised between equal foods? Yes! [Spinoza]
The mind is not free to remember or forget anything [Spinoza]
16. Persons / F. Free Will / 6. Determinism / a. Determinism
We think we are free because we don't know the causes of our desires and choices [Spinoza]
The actual world is the only one God could have created [Spinoza]
17. Mind and Body / A. Mind-Body Dualism / 5. Parallelism
Ideas and things have identical connections and order [Spinoza]
17. Mind and Body / A. Mind-Body Dualism / 8. Dualism of Mind Critique
Mind and body are one thing, seen sometimes as thought and sometimes as extension [Spinoza]
We are incapable of formulating an idea which excludes the existence of our body [Spinoza]
17. Mind and Body / E. Mind as Physical / 1. Physical Mind
Mind and body are the same thing, sometimes seen as thought, and sometimes as extension [Spinoza]
18. Thought / A. Modes of Thought / 3. Emotions / a. Nature of emotions
Emotion is a modification of bodily energy, controlling our actions [Spinoza]
18. Thought / A. Modes of Thought / 3. Emotions / e. Basic emotions
The three primary emotions are pleasure, pain and desire [Spinoza]
The three primary emotions are pleasure, pain, and desire [Spinoza, by Goldie]
18. Thought / A. Modes of Thought / 3. Emotions / f. Emotion and reason
Minds are subject to passions if they have inadequate ideas [Spinoza]
An emotion is only bad if it hinders us from thinking [Spinoza]
18. Thought / A. Modes of Thought / 3. Emotions / g. Controlling emotions
Stoics want to suppress emotions, but Spinoza overcomes them with higher emotions [Spinoza, by Stewart,M]
An emotion comes more under our control in proportion to how well it is known to us [Spinoza]
18. Thought / A. Modes of Thought / 6. Judgement / b. Error
People make calculation mistakes by misjudging the figures, not calculating them wrongly [Spinoza]
18. Thought / C. Content / 2. Ideas
Ideas are powerful entities, which can produce further ideas [Spinoza, by Schmid]
An 'idea' is a mental conception which is actively formed by the mind in thinking [Spinoza]
Ideas are not images formed in the brain, but are the conceptions of thought [Spinoza]
An idea involves affirmation or negation [Spinoza]
18. Thought / E. Abstraction / 7. Abstracta by Equivalence
An 'abstraction principle' says two things are identical if they are 'equivalent' in some respect [Boolos]
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 / a. Will to Act
Claiming that actions depend on the will is meaningless; no one knows what the will is [Spinoza]
Spinoza argues that in reality the will and the intellect are 'one and the same' [Spinoza, by Cottingham]
20. Action / C. Motives for Action / 1. Acting on Desires
Whenever we act, then desire is our very essence [Spinoza]
20. Action / C. Motives for Action / 4. Responsibility for Actions
We love or hate people more strongly because we think they are free [Spinoza]
We are the source of an action if only our nature can explain the action [Spinoza]
We act when it follows from our nature, and is understood in that way [Spinoza]
21. Aesthetics / A. Aesthetic Experience / 5. Natural Beauty
The most beautiful hand seen through the microscope will appear horrible [Spinoza]
22. Metaethics / A. Ethics Foundations / 1. Nature of Ethics / f. Ethical non-cognitivism
Whether nature is beautiful or orderly is entirely in relation to human imagination [Spinoza]
22. Metaethics / A. Ethics Foundations / 2. Source of Ethics / b. Rational ethics
Men only agree in nature if they are guided by reason [Spinoza]
We seek our own advantage, and virtue is doing this rationally [Spinoza]
22. Metaethics / A. Ethics Foundations / 2. Source of Ethics / e. Human nature
The essence of man is modifications of the nature of God [Spinoza]
By 'good' I mean what brings us ever closer to our model of human nature [Spinoza]
Along with his pantheism, Spinoza equates ethics with the study of human nature [Spinoza, by MacIntyre]
If infancy in humans was very rare, we would consider it a pitiful natural defect [Spinoza]
22. Metaethics / B. Value / 1. Nature of Value / d. Subjective value
We don't want things because they are good; we judge things to be good because we want them [Spinoza]
22. Metaethics / B. Value / 2. Values / g. Love
Love is joy with an external cause [Spinoza]
Love is nothing else but pleasure accompanied by the idea of an external cause [Spinoza]
22. Metaethics / B. Value / 2. Values / i. Self-interest
Spinoza names self-interest as the sole source of value [Spinoza, by Stewart,M]
22. Metaethics / B. Value / 2. Values / j. Evil
If our ideas were wholly adequate, we would have no concept of evil [Spinoza]
22. Metaethics / C. The Good / 1. Goodness / f. Good as pleasure
Music is good for a melancholic, bad for a mourner, and indifferent to the deaf [Spinoza]
22. Metaethics / C. The Good / 2. Happiness / d. Routes to happiness
Man's highest happiness consists of perfecting his understanding, or reason [Spinoza]
22. Metaethics / C. The Good / 3. Pleasure / a. Nature of pleasure
Pleasure is a passive state in which the mind increases in perfection [Spinoza]
22. Metaethics / C. The Good / 3. Pleasure / f. Dangers of pleasure
Pleasure is only bad in so far as it hinders a man's capability for action [Spinoza]
23. Ethics / A. Egoism / 1. Ethical Egoism
Reason demands nothing contrary to nature, and so it demands self-love [Spinoza]
Self-satisfaction is the highest thing for which we can hope [Spinoza]
23. Ethics / B. Contract Ethics / 1. Contractarianism
Both virtue and happiness are based on the preservation of one's own being [Spinoza]
23. Ethics / C. Virtue Theory / 1. Virtue Theory / b. Basis of virtue
To act virtuously is to act rationally [Spinoza]
The more we strive for our own advantage, the more virtuous we are [Spinoza]
All virtue is founded on self-preservation [Spinoza]
23. Ethics / C. Virtue Theory / 2. Elements of Virtue Theory / b. Living naturally
To live according to reason is to live according to the laws of human nature [Spinoza]
23. Ethics / C. Virtue Theory / 2. Elements of Virtue Theory / j. Unity of virtue
A man ignorant of himself is ignorant of all of the virtues [Spinoza]
23. Ethics / C. Virtue Theory / 3. Virtues / d. Courage
In a free man, choosing flight can show as much strength of mind as fighting [Spinoza]
23. Ethics / C. Virtue Theory / 3. Virtues / f. Compassion
A person unmoved by either reason or pity to help others is rightly called 'inhuman' [Spinoza]
Pity is a bad and useless thing, as it is a pain, and rational people perform good deeds without it [Spinoza]
Pity is not a virtue, but at least it shows a desire to live uprightly [Spinoza]
People who live according to reason should avoid pity [Spinoza]
23. Ethics / C. Virtue Theory / 4. External Goods / c. Wealth
Rational people judge money by needs, and live contented with very little [Spinoza]
23. Ethics / D. Deontological Ethics / 3. Universalisability
Rational people are self-interested, but also desire the same goods for other people [Spinoza]
A rational person will want others to have the goods he seeks for himself [Spinoza]
24. Political Theory / A. Basis of a State / 1. A People / a. Human distinctiveness
If people are obedient to reason, they will live in harmony [Spinoza]
24. Political Theory / A. Basis of a State / 1. A People / c. A unified people
Peoples are created by individuals, not by nature, and only distinguished by language and law [Spinoza]
The ideal for human preservation is unanimity among people [Spinoza]
24. Political Theory / A. Basis of a State / 3. Natural Values / a. Natural freedom
Only self-knowledge can liberate us [Spinoza, by MacIntyre]
24. Political Theory / A. Basis of a State / 3. Natural Values / c. Natural rights
In nature everything has an absolute right to do anything it is capable of doing [Spinoza]
Natural rights are determined by desire and power, not by reason [Spinoza]
Spinoza extended Hobbes's natural rights to cover all possible desires and actions [Spinoza, by Tuck]
24. Political Theory / B. Nature of a State / 1. Purpose of a State
Society exists to extend human awareness [Spinoza, by Watson]
The state aims to allow personal development, so its main purpose is freedom [Spinoza]
24. Political Theory / B. Nature of a State / 2. State Legitimacy / a. Sovereignty
Sovereignty must include the power to make people submit to it [Spinoza]
24. Political Theory / C. Ruling a State / 2. Leaders / b. Monarchy
Kings tend to fight wars for glory, rather than for peace and liberty [Spinoza]
Monarchs are always proud, and can't back down [Spinoza]
Deposing a monarch is dangerous, because the people are used to royal authority [Spinoza]
24. Political Theory / C. Ruling a State / 4. Changing the State / c. Revolution
Every state is more frightened of its own citizens than of external enemies [Spinoza]
24. Political Theory / D. Ideologies / 5. Democracy / c. Direct democracy
Democracy is a legitimate gathering of people who do whatever they can do [Spinoza]
24. Political Theory / D. Ideologies / 10. Theocracy
If religion is law, then piety is justice, impiety is crime, and non-believers must leave [Spinoza]
Allowing religious ministers any control of the state is bad for both parties [Spinoza]
25. Social Practice / A. Freedoms / 1. Slavery
Slavery is a disgraceful crime [Spinoza]
Slavery is not just obedience, but acting only in the interests of the master [Spinoza]
25. Social Practice / A. Freedoms / 2. Freedom of belief
Government is oppressive if opinions can be crimes, because people can't give them up [Spinoza]
Without liberty of thought there is no trust in the state, and corruption follows [Spinoza]
25. Social Practice / A. Freedoms / 3. Free speech
Treason may be committed as much by words as by deeds [Spinoza]
25. Social Practice / A. Freedoms / 6. Political freedom
The freest state is a rational one, where people can submit themselves to reason [Spinoza]
25. Social Practice / C. Rights / 1. Basis of Rights
Spinoza wanted democracy based on individual rights, and is thus the first modern political philosopher [Stewart,M on Spinoza]
The sovereignty has absolute power over citizens [Spinoza]
25. Social Practice / C. Rights / 3. Alienating rights
Forming a society meant following reason, and giving up dangerous appetites and mutual harm [Spinoza]
People only give up their rights, and keep promises, if they hope for some greater good [Spinoza]
Once you have given up your rights, there is no going back [Spinoza]
In democracy we don't abandon our rights, but transfer them to the majority of us [Spinoza]
No one, in giving up their power and right, ceases to be a human being [Spinoza]
Everyone who gives up their rights must fear the recipients of them [Spinoza]
The early Hebrews, following Moses, gave up their rights to God alone [Spinoza]
25. Social Practice / D. Justice / 2. The Law / c. Natural law
The order of nature does not prohibit anything, and allows whatever appetite produces [Spinoza]
25. Social Practice / E. Policies / 2. Religion in Society
State and religious law can clash, so the state must make decisions about religion [Spinoza]
25. Social Practice / E. Policies / 5. Education / c. Teaching
The best use of talent is to teach other people to live rationally [Spinoza]
25. Social Practice / F. Life Issues / 4. Suicide
It is impossible that the necessity of a person's nature should produce a desire for non-existence [Spinoza]
25. Social Practice / F. Life Issues / 6. Animal Rights
Animals feel, but that doesn't mean we can't use them for our pleasure and profit [Spinoza]
26. Natural Theory / A. Speculations on Nature / 1. Nature
We can easily think of nature as one individual [Spinoza]
26. Natural Theory / A. Speculations on Nature / 2. Natural Purpose / b. Limited purposes
Nature has no particular goal in view, and final causes are mere human figments [Spinoza]
26. Natural Theory / A. Speculations on Nature / 2. Natural Purpose / c. Purpose denied
Spinoza strongly attacked teleology, which is the lifeblood of classical logos [Roochnik on Spinoza]
For Spinoza eyes don't act for purposes, but follow mechanical necessity [Roochnik on Spinoza]
Final causes are figments of human imagination [Spinoza]
26. Natural Theory / A. Speculations on Nature / 5. Infinite in Nature
An infinite line can be marked in feet or inches, so one infinity is twelve times the other [Spinoza]
26. Natural Theory / A. Speculations on Nature / 6. Early Matter Theories / c. Ultimate substances
In nature there is just one infinite substance [Spinoza]
26. Natural Theory / C. Causation / 3. Final causes
A final cause is simply a human desire [Spinoza]
26. Natural Theory / C. Causation / 9. General Causation / d. Causal necessity
From a definite cause an effect necessarily follows [Spinoza]
28. God / A. Divine Nature / 1. God
The key question for Spinoza is: is his God really a God? [Stewart,M on Spinoza]
28. God / A. Divine Nature / 2. Divine Nature
God feels no emotions, of joy or sorrow [Spinoza]
God has no purpose, because God lacks nothing [Spinoza]
Spinoza's God is just power and necessity, without perfection or wisdom [Leibniz on Spinoza]
Spinoza's God is not a person [Spinoza, by Jolley]
God is wholly without passions, and strictly speaking does not love anyone [Spinoza, by Cottingham]
God is the sum and principle of all eternal laws [Spinoza, by Armstrong,K]
God is not loveable for producing without choice and by necessity; God is loveable for his goodness [Leibniz on Spinoza]
God is a substance with infinite attributes [Spinoza]
God does not act according to the freedom of the will [Spinoza]
28. God / A. Divine Nature / 3. Divine Perfections
God is a being with infinite attributes, each of them infinite or perfect [Spinoza]
God no more has human perfections than we have animal perfections [Spinoza]
28. God / A. Divine Nature / 6. Divine Morality / c. God is the good
To say that God promotes what is good is false, as it sets up a goal beyond God [Spinoza]
28. God / B. Proving God / 2. Proofs of Reason / a. Ontological Proof
Spinoza says a substance of infinite attributes cannot fail to exist [Spinoza, by Lord]
Denial of God is denial that his essence involves existence, which is absurd [Spinoza]
God is being as such, and you cannot conceive of the non-existence of being [Spinoza, by Lord]
God must necessarily exist, because no reason can be given for his non-existence [Spinoza]
Some things makes me conceive of it as a thing whose essence requires its existence [Spinoza]
28. God / B. Proving God / 2. Proofs of Reason / b. Ontological Proof critique
If a thing can be conceived as non-existing, its essence does not involve existence [Spinoza]
28. God / B. Proving God / 3. Proofs of Evidence / e. Miracles
Trying to prove God's existence through miracles is proving the obscure by the more obscure [Spinoza]
Priests reject as heretics anyone who tries to understand miracles in a natural way [Spinoza]
28. God / C. Attitudes to God / 2. Pantheism
That God is the substance of all things is an ill-reputed doctrine [Leibniz on Spinoza]
The human mind is part of the infinite intellect of God [Spinoza]
God is the efficient cause of essences, as well as of existences [Spinoza]
Everything is in God, and nothing exists or is thinkable without God [Spinoza]
28. God / C. Attitudes to God / 4. God Reflects Humanity
A talking triangle would say God is triangular [Spinoza]
28. God / C. Attitudes to God / 5. Atheism
In Spinoza, one could substitute 'nature' or 'substance' for the word 'God' throughout [Spinoza, by Stewart,M]
29. Religion / B. Monotheistic Religion / 2. Judaism
Hebrews were very hostile to other states, who had not given up their rights to God [Spinoza]
29. Religion / B. Monotheistic Religion / 5. Bible
The Bible has nothing in common with reasoning and philosophy [Spinoza]
29. Religion / D. Religious Issues / 2. Immortality / a. Immortality
Spinoza's theory of mind implies that there is no immortality [Spinoza, by Stewart,M]
After death, something eternal remains of the mind [Spinoza]