Combining Philosophers

All the ideas for Penelope Maddy, Roy Sorensen and David S. Oderberg

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99 ideas

1. Philosophy / F. Analytic Philosophy / 7. Limitations of Analysis
The paradox of analysis says that any conceptual analysis must be either trivial or false [Sorensen]
2. Reason / B. Laws of Thought / 1. Laws of Thought
Two long understandable sentences can have an unintelligible conjunction [Sorensen]
2. Reason / D. Definition / 5. Genus and Differentia
'Animal' is a genus and 'rational' is a specific difference [Oderberg]
Definition distinguishes one kind from another, and individuation picks out members of the kind [Oderberg]
3. Truth / B. Truthmakers / 6. Making Negative Truths
If nothing exists, no truthmakers could make 'Nothing exists' true [Sorensen]
3. Truth / B. Truthmakers / 12. Rejecting Truthmakers
Which toothbrush is the truthmaker for 'buy one, get one free'? [Sorensen]
4. Formal Logic / F. Set Theory ST / 2. Mechanics of Set Theory / b. Terminology of ST
'Forcing' can produce new models of ZFC from old models [Maddy]
4. Formal Logic / F. Set Theory ST / 4. Axioms for Sets / a. Axioms for sets
A Large Cardinal Axiom would assert ever-increasing stages in the hierarchy [Maddy]
New axioms are being sought, to determine the size of the continuum [Maddy]
4. Formal Logic / F. Set Theory ST / 4. Axioms for Sets / b. Axiom of Extensionality I
The Axiom of Extensionality seems to be analytic [Maddy]
Extensional sets are clearer, simpler, unique and expressive [Maddy]
4. Formal Logic / F. Set Theory ST / 4. Axioms for Sets / f. Axiom of Infinity V
Axiom of Infinity: completed infinite collections can be treated mathematically [Maddy]
The Axiom of Infinity states Cantor's breakthrough that launched modern mathematics [Maddy]
Infinite sets are essential for giving an account of the real numbers [Maddy]
4. Formal Logic / F. Set Theory ST / 4. Axioms for Sets / g. Axiom of Powers VI
The Power Set Axiom is needed for, and supported by, accounts of the continuum [Maddy]
4. Formal Logic / F. Set Theory ST / 4. Axioms for Sets / i. Axiom of Foundation VIII
The Axiom of Foundation says every set exists at a level in the set hierarchy [Maddy]
4. Formal Logic / F. Set Theory ST / 4. Axioms for Sets / j. Axiom of Choice IX
Efforts to prove the Axiom of Choice have failed [Maddy]
Modern views say the Choice set exists, even if it can't be constructed [Maddy]
A large array of theorems depend on the Axiom of Choice [Maddy]
The Axiom of Choice paradoxically allows decomposing a sphere into two identical spheres [Maddy]
4. Formal Logic / F. Set Theory ST / 4. Axioms for Sets / p. Axiom of Reducibility
Axiom of Reducibility: propositional functions are extensionally predicative [Maddy]
4. Formal Logic / F. Set Theory ST / 5. Conceptions of Set / e. Iterative sets
The Iterative Conception says everything appears at a stage, derived from the preceding appearances [Maddy]
4. Formal Logic / F. Set Theory ST / 5. Conceptions of Set / f. Limitation of Size
Limitation of Size is a vague intuition that over-large sets may generate paradoxes [Maddy]
4. Formal Logic / F. Set Theory ST / 7. Natural Sets
The master science is physical objects divided into sets [Maddy]
Maddy replaces pure sets with just objects and perceived sets of objects [Maddy, by Shapiro]
5. Theory of Logic / A. Overview of Logic / 7. Second-Order Logic
Henkin semantics is more plausible for plural logic than for second-order logic [Maddy]
5. Theory of Logic / C. Ontology of Logic / 3. If-Thenism
Critics of if-thenism say that not all starting points, even consistent ones, are worth studying [Maddy]
5. Theory of Logic / D. Assumptions for Logic / 1. Bivalence
No attempt to deny bivalence has ever been accepted [Sorensen]
5. Theory of Logic / E. Structures of Logic / 1. Logical Form
'Propositional functions' are propositions with a variable as subject or predicate [Maddy]
5. Theory of Logic / E. Structures of Logic / 4. Variables in Logic
We now see that generalizations use variables rather than abstract entities [Sorensen]
5. Theory of Logic / K. Features of Logics / 1. Axiomatisation
Hilbert's geometry and Dedekind's real numbers were role models for axiomatization [Maddy]
If two mathematical themes coincide, that suggest a single deep truth [Maddy]
5. Theory of Logic / L. Paradox / 3. Antinomies
Denying problems, or being romantically defeated by them, won't make them go away [Sorensen]
5. Theory of Logic / L. Paradox / 6. Paradoxes in Language / a. The Liar paradox
Banning self-reference would outlaw 'This very sentence is in English' [Sorensen]
6. Mathematics / A. Nature of Mathematics / 3. Nature of Numbers / a. Numbers
The Aristotelian view is that numbers depend on (and are abstracted from) other things [Oderberg]
6. Mathematics / A. Nature of Mathematics / 5. The Infinite / d. Actual infinite
Completed infinities resulted from giving foundations to calculus [Maddy]
Cantor and Dedekind brought completed infinities into mathematics [Maddy]
6. Mathematics / A. Nature of Mathematics / 5. The Infinite / g. Continuum Hypothesis
Every infinite set of reals is either countable or of the same size as the full set of reals [Maddy]
6. Mathematics / A. Nature of Mathematics / 5. The Infinite / i. Cardinal infinity
Infinity has degrees, and large cardinals are the heart of set theory [Maddy]
For any cardinal there is always a larger one (so there is no set of all sets) [Maddy]
An 'inaccessible' cardinal cannot be reached by union sets or power sets [Maddy]
6. Mathematics / A. Nature of Mathematics / 5. The Infinite / l. Limits
Theorems about limits could only be proved once the real numbers were understood [Maddy]
6. Mathematics / B. Foundations for Mathematics / 5. Definitions of Number / c. Fregean numbers
The extension of concepts is not important to me [Maddy]
In the ZFC hierarchy it is impossible to form Frege's set of all three-element sets [Maddy]
6. Mathematics / B. Foundations for Mathematics / 5. Definitions of Number / e. Caesar problem
Frege solves the Caesar problem by explicitly defining each number [Maddy]
6. Mathematics / B. Foundations for Mathematics / 6. Mathematics as Set Theory / a. Mathematics is set theory
Set theory (unlike the Peano postulates) can explain why multiplication is commutative [Maddy]
Standardly, numbers are said to be sets, which is neat ontology and epistemology [Maddy]
Numbers are properties of sets, just as lengths are properties of physical objects [Maddy]
A natural number is a property of sets [Maddy, by Oliver]
Making set theory foundational to mathematics leads to very fruitful axioms [Maddy]
Unified set theory gives a final court of appeal for mathematics [Maddy]
Set theory brings mathematics into one arena, where interrelations become clearer [Maddy]
Identifying geometric points with real numbers revealed the power of set theory [Maddy]
The line of rationals has gaps, but set theory provided an ordered continuum [Maddy]
Set-theory tracks the contours of mathematical depth and fruitfulness [Maddy]
Mathematics rests on the logic of proofs, and on the set theoretic axioms [Maddy]
6. Mathematics / B. Foundations for Mathematics / 6. Mathematics as Set Theory / b. Mathematics is not set theory
Number theory doesn't 'reduce' to set theory, because sets have number properties [Maddy]
Sets exist where their elements are, but numbers are more like universals [Maddy]
6. Mathematics / C. Sources of Mathematics / 1. Mathematical Platonism / b. Against mathematical platonism
If mathematical objects exist, how can we know them, and which objects are they? [Maddy]
6. Mathematics / C. Sources of Mathematics / 2. Intuition of Mathematics
Intuition doesn't support much mathematics, and we should question its reliability [Maddy, by Shapiro]
6. Mathematics / C. Sources of Mathematics / 4. Mathematical Empiricism / a. Mathematical empiricism
We know mind-independent mathematical truths through sets, which rest on experience [Maddy, by Jenkins]
6. Mathematics / C. Sources of Mathematics / 4. Mathematical Empiricism / b. Indispensability of mathematics
Scientists posit as few entities as possible, but set theorist posit as many as possible [Maddy]
Maybe applications of continuum mathematics are all idealisations [Maddy]
6. Mathematics / C. Sources of Mathematics / 4. Mathematical Empiricism / c. Against mathematical empiricism
The connection of arithmetic to perception has been idealised away in modern infinitary mathematics [Maddy]
6. Mathematics / C. Sources of Mathematics / 5. Numbers as Adjectival
Number words are unusual as adjectives; we don't say 'is five', and numbers always come first [Maddy]
6. Mathematics / C. Sources of Mathematics / 6. Logicism / c. Neo-logicism
We can get arithmetic directly from HP; Law V was used to get HP from the definition of number [Maddy]
7. Existence / A. Nature of Existence / 3. Being / a. Nature of Being
Being is substantial/accidental, complete/incomplete, necessary/contingent, possible, relative, intrinsic.. [Oderberg]
7. Existence / D. Theories of Reality / 10. Vagueness / c. Vagueness as ignorance
Vague words have hidden boundaries [Sorensen]
7. Existence / D. Theories of Reality / 11. Ontological Commitment / e. Ontological commitment problems
The theoretical indispensability of atoms did not at first convince scientists that they were real [Maddy]
8. Modes of Existence / B. Properties / 13. Tropes / b. Critique of tropes
If tropes are in space and time, in what sense are they abstract? [Oderberg]
8. Modes of Existence / C. Powers and Dispositions / 4. Powers as Essence
We need to distinguish the essential from the non-essential powers [Oderberg]
9. Objects / B. Unity of Objects / 2. Substance / e. Substance critique
Empiricists gave up 'substance', as unknowable substratum, or reducible to a bundle [Oderberg]
9. Objects / B. Unity of Objects / 3. Unity Problems / e. Vague objects
An offer of 'free coffee or juice' could slowly shift from exclusive 'or' to inclusive 'or' [Sorensen]
9. Objects / D. Essence of Objects / 1. Essences of Objects
Essences are real, about being, knowable, definable and classifiable [Oderberg, by PG]
9. Objects / D. Essence of Objects / 3. Individual Essences
Nominalism is consistent with individual but not with universal essences [Oderberg]
9. Objects / D. Essence of Objects / 6. Essence as Unifier
Essentialism is the main account of the unity of objects [Oderberg]
9. Objects / D. Essence of Objects / 8. Essence as Explanatory
Essence is not explanatory but constitutive [Oderberg]
9. Objects / D. Essence of Objects / 9. Essence and Properties
Properties are not part of an essence, but they flow from it [Oderberg]
9. Objects / D. Essence of Objects / 15. Against Essentialism
Could we replace essence with collections of powers? [Oderberg]
9. Objects / F. Identity among Objects / 8. Leibniz's Law
Leibniz's Law is an essentialist truth [Oderberg]
10. Modality / B. Possibility / 4. Potentiality
Bodies have act and potency, the latter explaining new kinds of existence [Oderberg]
10. Modality / E. Possible worlds / 1. Possible Worlds / e. Against possible worlds
Realism about possible worlds is circular, since it needs a criterion of 'possible' [Oderberg]
10. Modality / E. Possible worlds / 3. Transworld Objects / a. Transworld identity
Necessity of identity seems trivial, because it leaves out the real essence [Oderberg]
10. Modality / E. Possible worlds / 3. Transworld Objects / b. Rigid designation
Rigid designation has at least three essentialist presuppositions [Oderberg]
12. Knowledge Sources / A. A Priori Knowledge / 1. Nature of the A Priori
It is propositional attitudes which can be a priori, not the propositions themselves [Sorensen]
Attributing apriority to a proposition is attributing a cognitive ability to someone [Sorensen]
12. Knowledge Sources / B. Perception / 2. Qualities in Perception / d. Secondary qualities
The colour bands of the spectrum arise from our biology; they do not exist in the physics [Sorensen]
12. Knowledge Sources / B. Perception / 5. Interpretation
We are unable to perceive a nose (on the back of a mask) as concave [Sorensen]
13. Knowledge Criteria / B. Internal Justification / 5. Coherentism / b. Pro-coherentism
Bayesians build near-certainty from lots of reasonably probable beliefs [Sorensen]
13. Knowledge Criteria / D. Scepticism / 3. Illusion Scepticism
Illusions are not a reason for skepticism, but a source of interesting scientific information [Sorensen]
15. Nature of Minds / C. Capacities of Minds / 6. Idealisation
Science idealises the earth's surface, the oceans, continuities, and liquids [Maddy]
19. Language / A. Nature of Meaning / 5. Meaning as Verification
The negation of a meaningful sentence must itself be meaningful [Sorensen]
19. Language / D. Propositions / 4. Mental Propositions
Propositions are what settle problems of ambiguity in sentences [Sorensen]
25. Social Practice / A. Freedoms / 4. Free market
I can buy any litre of water, but not every litre of water [Sorensen]
26. Natural Theory / A. Speculations on Nature / 3. Natural Function
Essence is the source of a thing's characteristic behaviour [Oderberg]
26. Natural Theory / A. Speculations on Nature / 6. Early Matter Theories / e. The One
What makes Parmenidean reality a One rather than a Many? [Oderberg]
26. Natural Theory / D. Laws of Nature / 8. Scientific Essentialism / a. Scientific essentialism
The real essentialist is not merely a scientist [Oderberg]
26. Natural Theory / D. Laws of Nature / 8. Scientific Essentialism / e. Anti scientific essentialism
The reductionism found in scientific essentialism is mistaken [Oderberg]
28. God / A. Divine Nature / 4. Divine Contradictions
God cannot experience unwanted pain, so God cannot understand human beings [Sorensen]