Combining Philosophers

All the ideas for Harry G. Frankfurt, Karl Leonhard Reinhold and Penelope Maddy

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81 ideas

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
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]
Axiom of Infinity: completed infinite collections can be treated mathematically [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 / E. Structures of Logic / 1. Logical Form
'Propositional functions' are propositions with a variable as subject or predicate [Maddy]
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]
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 / 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]
10. Modality / A. Necessity / 9. Normative Necessity
Love creates a necessity concerning what to care about [Frankfurt]
12. Knowledge Sources / B. Perception / 4. Sense Data / b. Nature of sense-data
Subjects distinguish representations, as related both to subject and object [Reinhold]
15. Nature of Minds / C. Capacities of Minds / 6. Idealisation
Science idealises the earth's surface, the oceans, continuities, and liquids [Maddy]
16. Persons / B. Nature of the Self / 6. Self as Higher Awareness
Persons are distinguished by a capacity for second-order desires [Frankfurt]
A person essentially has second-order volitions, and not just second-order desires [Frankfurt]
16. Persons / F. Free Will / 1. Nature of Free Will
Free will is the capacity to choose what sort of will you have [Frankfurt]
20. Action / B. Preliminaries of Action / 2. Willed Action / a. Will to Act
The will is the effective desire which actually leads to an action [Frankfurt]
20. Action / B. Preliminaries of Action / 2. Willed Action / c. Agent causation
Freedom of action needs the agent to identify with their reason for acting [Frankfurt, by Wilson/Schpall]
22. Metaethics / A. Ethics Foundations / 1. Nature of Ethics / d. Ethical theory
Ranking order of desires reveals nothing, because none of them may be considered important [Frankfurt]
22. Metaethics / A. Ethics Foundations / 1. Nature of Ethics / g. Moral responsibility
A 'wanton' is not a person, because they lack second-order volitions [Frankfurt]
A person may be morally responsible without free will [Frankfurt]
22. Metaethics / A. Ethics Foundations / 2. Source of Ethics / b. Rational ethics
Morality isn't based on reason; moral indignation is quite unlike disapproval of irrationality [Frankfurt]
22. Metaethics / B. Value / 1. Nature of Value / d. Subjective value
It is by caring about things that we infuse the world with importance [Frankfurt]
If you don't care about at least one thing, you can't find reasons to care about anything [Frankfurt]
22. Metaethics / B. Value / 1. Nature of Value / f. Ultimate value
What is worthwhile for its own sake alone may be worth very little [Frankfurt]
Our criteria for evaluating how to live offer an answer to the problem [Frankfurt]
22. Metaethics / B. Value / 2. Values / g. Love
Rather than loving things because we value them, I think we value things because we love them [Frankfurt]
Love can be cool, and it may not involve liking its object [Frankfurt]
The paradigm case of pure love is not romantic, but that between parents and infants [Frankfurt]
I value my children for their sake, but I also value my love for them for its own sake [Frankfurt]
22. Metaethics / C. The Good / 2. Happiness / d. Routes to happiness
We might not choose a very moral life, if the character or constitution was deficient [Frankfurt]
22. Metaethics / C. The Good / 3. Pleasure / a. Nature of pleasure
People want to fulfill their desires, but also for their desires to be sustained [Frankfurt]
23. Ethics / A. Egoism / 1. Ethical Egoism
Loving oneself is not a failing, but is essential to a successful life [Frankfurt]
23. Ethics / F. Existentialism / 4. Boredom
Boredom is serious, not just uncomfortable; it threatens our psychic survival [Frankfurt]
25. Social Practice / A. Freedoms / 5. Freedom of lifestyle
Freedom needs autonomy (rather than causal independence) - embracing our own desires and choices [Frankfurt]