Combining Philosophers

All the ideas for Dorothy Edgington, Alan Musgrave and Paul Benacerraf

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67 ideas

4. Formal Logic / B. Propositional Logic PL / 2. Tools of Propositional Logic / c. Derivation rules of PL
Conditional Proof is only valid if we accept the truth-functional reading of 'if' [Edgington]
5. Theory of Logic / C. Ontology of Logic / 3. If-Thenism
Perhaps If-thenism survives in mathematics if we stick to first-order logic [Musgrave]
The If-thenist view only seems to work for the axiomatised portions of mathematics [Musgrave]
5. Theory of Logic / I. Semantics of Logic / 3. Logical Truth
A statement is logically true if it comes out true in all interpretations in all (non-empty) domains [Musgrave]
Logical truths may contain non-logical notions, as in 'all men are men' [Musgrave]
6. Mathematics / A. Nature of Mathematics / 1. Mathematics
Mathematical truth is always compromising between ordinary language and sensible epistemology [Benacerraf]
6. Mathematics / A. Nature of Mathematics / 3. Nature of Numbers / a. Numbers
There are no such things as numbers [Benacerraf]
Obtaining numbers by abstraction is impossible - there are too many; only a rule could give them, in order [Benacerraf]
We must explain how we know so many numbers, and recognise ones we haven't met before [Benacerraf]
Numbers can't be sets if there is no agreement on which sets they are [Benacerraf]
6. Mathematics / A. Nature of Mathematics / 3. Nature of Numbers / c. Priority of numbers
If numbers are basically the cardinals (Frege-Russell view) you could know some numbers in isolation [Benacerraf]
Benacerraf says numbers are defined by their natural ordering [Benacerraf, by Fine,K]
6. Mathematics / A. Nature of Mathematics / 3. Nature of Numbers / f. Cardinal numbers
To understand finite cardinals, it is necessary and sufficient to understand progressions [Benacerraf, by Wright,C]
A set has k members if it one-one corresponds with the numbers less than or equal to k [Benacerraf]
To explain numbers you must also explain cardinality, the counting of things [Benacerraf]
6. Mathematics / A. Nature of Mathematics / 4. Using Numbers / c. Counting procedure
We can count intransitively (reciting numbers) without understanding transitive counting of items [Benacerraf]
Someone can recite numbers but not know how to count things; but not vice versa [Benacerraf]
6. Mathematics / A. Nature of Mathematics / 4. Using Numbers / g. Applying mathematics
The application of a system of numbers is counting and measurement [Benacerraf]
6. Mathematics / B. Foundations for Mathematics / 4. Axioms for Number / a. Axioms for numbers
The successor of x is either x and all its members, or just the unit set of x [Benacerraf]
For Zermelo 3 belongs to 17, but for Von Neumann it does not [Benacerraf]
6. Mathematics / B. Foundations for Mathematics / 4. Axioms for Number / d. Peano arithmetic
No two numbers having the same successor relies on the Axiom of Infinity [Musgrave]
6. Mathematics / B. Foundations for Mathematics / 6. Mathematics as Set Theory / b. Mathematics is not set theory
Disputes about mathematical objects seem irrelevant, and mathematicians cannot resolve them [Benacerraf, by Friend]
No particular pair of sets can tell us what 'two' is, just by one-to-one correlation [Benacerraf, by Lowe]
If ordinal numbers are 'reducible to' some set-theory, then which is which? [Benacerraf]
6. Mathematics / B. Foundations for Mathematics / 7. Mathematical Structuralism / a. Structuralism
An adequate account of a number must relate it to its series [Benacerraf]
The job is done by the whole system of numbers, so numbers are not objects [Benacerraf]
If any recursive sequence will explain ordinals, then it seems to be the structure which matters [Benacerraf]
The number 3 defines the role of being third in a progression [Benacerraf]
Number words no more have referents than do the parts of a ruler [Benacerraf]
Mathematical objects only have properties relating them to other 'elements' of the same structure [Benacerraf]
How can numbers be objects if order is their only property? [Benacerraf, by Putnam]
6. Mathematics / C. Sources of Mathematics / 1. Mathematical Platonism / b. Against mathematical platonism
Number-as-objects works wholesale, but fails utterly object by object [Benacerraf]
Realists have semantics without epistemology, anti-realists epistemology but bad semantics [Benacerraf, by Colyvan]
The platonist view of mathematics doesn't fit our epistemology very well [Benacerraf]
6. Mathematics / C. Sources of Mathematics / 5. Numbers as Adjectival
Number words are not predicates, as they function very differently from adjectives [Benacerraf]
6. Mathematics / C. Sources of Mathematics / 6. Logicism / d. Logicism critique
The set-theory paradoxes mean that 17 can't be the class of all classes with 17 members [Benacerraf]
6. Mathematics / C. Sources of Mathematics / 7. Formalism
Formalism is a bulwark of logical positivism [Musgrave]
Formalism seems to exclude all creative, growing mathematics [Musgrave]
9. Objects / F. Identity among Objects / 6. Identity between Objects
Identity statements make sense only if there are possible individuating conditions [Benacerraf]
10. Modality / A. Necessity / 1. Types of Modality
There are two families of modal notions, metaphysical and epistemic, of equal strength [Edgington]
10. Modality / A. Necessity / 5. Metaphysical Necessity
Metaphysical possibility is discovered empirically, and is contrained by nature [Edgington]
10. Modality / A. Necessity / 6. Logical Necessity
Broadly logical necessity (i.e. not necessarily formal logical necessity) is an epistemic notion [Edgington]
An argument is only valid if it is epistemically (a priori) necessary [Edgington]
Logical necessity is epistemic necessity, which is the old notion of a priori [Edgington, by McFetridge]
10. Modality / B. Possibility / 6. Probability
Truth-functional possibilities include the irrelevant, which is a mistake [Edgington]
A thing works like formal probability if all the options sum to 100% [Edgington]
Conclusion improbability can't exceed summed premise improbability in valid arguments [Edgington]
10. Modality / B. Possibility / 8. Conditionals / a. Conditionals
It is a mistake to think that conditionals are statements about how the world is [Edgington]
Validity can preserve certainty in mathematics, but conditionals about contingents are another matter [Edgington]
10. Modality / B. Possibility / 8. Conditionals / b. Types of conditional
There are many different conditional mental states, and different conditional speech acts [Edgington]
Simple indicatives about past, present or future do seem to form a single semantic kind [Edgington]
Maybe forward-looking indicatives are best classed with the subjunctives [Edgington]
10. Modality / B. Possibility / 8. Conditionals / c. Truth-function conditionals
Truth-function problems don't show up in mathematics [Edgington]
Are conditionals truth-functional - do the truth values of A and B determine the truth value of 'If A, B'? [Edgington]
'If A,B' must entail ¬(A & ¬B); otherwise we could have A true, B false, and If A,B true, invalidating modus ponens [Edgington]
Inferring conditionals from disjunctions or negated conjunctions gives support to truth-functionalism [Edgington]
The truth-functional view makes conditionals with unlikely antecedents likely to be true [Edgington]
Doctor:'If patient still alive, change dressing'; Nurse:'Either dead patient, or change dressing'; kills patient! [Edgington]
10. Modality / B. Possibility / 8. Conditionals / d. Non-truthfunction conditionals
A conditional does not have truth conditions [Edgington]
X believes 'if A, B' to the extent that A & B is more likely than A & ¬B [Edgington]
Non-truth-functionalist say 'If A,B' is false if A is T and B is F, but deny that is always true for TT,FT and FF [Edgington]
I say "If you touch that wire you'll get a shock"; you don't touch it. How can that make the conditional true? [Edgington]
10. Modality / B. Possibility / 8. Conditionals / e. Supposition conditionals
Conditionals express what would be the outcome, given some supposition [Edgington]
On the supposition view, believe if A,B to the extent that A&B is nearly as likely as A [Edgington]
10. Modality / B. Possibility / 8. Conditionals / f. Pragmatics of conditionals
Truth-functionalists support some conditionals which we assert, but should not actually believe [Edgington]
Does 'If A,B' say something different in each context, because of the possibiites there? [Edgington]
19. Language / A. Nature of Meaning / 5. Meaning as Verification
Logical positivists adopted an If-thenist version of logicism about numbers [Musgrave]