Combining Philosophers

All the ideas for Hermarchus, Brian Clegg and Michael Devitt

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36 ideas

4. Formal Logic / F. Set Theory ST / 2. Mechanics of Set Theory / b. Terminology of ST
A set is 'well-ordered' if every subset has a first element [Clegg]
4. Formal Logic / F. Set Theory ST / 3. Types of Set / d. Infinite Sets
Set theory made a closer study of infinity possible [Clegg]
Any set can always generate a larger set - its powerset, of subsets [Clegg]
4. Formal Logic / F. Set Theory ST / 4. Axioms for Sets / b. Axiom of Extensionality I
Extensionality: Two sets are equal if and only if they have the same elements [Clegg]
4. Formal Logic / F. Set Theory ST / 4. Axioms for Sets / c. Axiom of Pairing II
Pairing: For any two sets there exists a set to which they both belong [Clegg]
4. Formal Logic / F. Set Theory ST / 4. Axioms for Sets / d. Axiom of Unions III
Unions: There is a set of all the elements which belong to at least one set in a collection [Clegg]
4. Formal Logic / F. Set Theory ST / 4. Axioms for Sets / f. Axiom of Infinity V
Infinity: There exists a set of the empty set and the successor of each element [Clegg]
4. Formal Logic / F. Set Theory ST / 4. Axioms for Sets / g. Axiom of Powers VI
Powers: All the subsets of a given set form their own new powerset [Clegg]
4. Formal Logic / F. Set Theory ST / 4. Axioms for Sets / j. Axiom of Choice IX
Choice: For every set a mechanism will choose one member of any non-empty subset [Clegg]
4. Formal Logic / F. Set Theory ST / 4. Axioms for Sets / k. Axiom of Existence
Axiom of Existence: there exists at least one set [Clegg]
4. Formal Logic / F. Set Theory ST / 4. Axioms for Sets / l. Axiom of Specification
Specification: a condition applied to a set will always produce a new set [Clegg]
6. Mathematics / A. Nature of Mathematics / 1. Mathematics
Mathematics can be 'pure' (unapplied), 'real' (physically grounded); or 'applied' (just applicable) [Clegg]
6. Mathematics / A. Nature of Mathematics / 3. Nature of Numbers / e. Ordinal numbers
Beyond infinity cardinals and ordinals can come apart [Clegg]
An ordinal number is defined by the set that comes before it [Clegg]
6. Mathematics / A. Nature of Mathematics / 3. Nature of Numbers / g. Real numbers
Transcendental numbers can't be fitted to finite equations [Clegg]
6. Mathematics / A. Nature of Mathematics / 3. Nature of Numbers / k. Imaginary numbers
By adding an axis of imaginary numbers, we get the useful 'number plane' instead of number line [Clegg]
6. Mathematics / A. Nature of Mathematics / 3. Nature of Numbers / l. Zero
Either lack of zero made early mathematics geometrical, or the geometrical approach made zero meaningless [Clegg]
6. Mathematics / A. Nature of Mathematics / 5. The Infinite / a. The Infinite
Cantor's account of infinities has the shaky foundation of irrational numbers [Clegg]
6. Mathematics / A. Nature of Mathematics / 5. The Infinite / g. Continuum Hypothesis
The Continuum Hypothesis is independent of the axioms of set theory [Clegg]
The 'continuum hypothesis' says aleph-one is the cardinality of the reals [Clegg]
8. Modes of Existence / D. Universals / 1. Universals
Realism doesn't explain 'a is F' any further by saying it is 'a has F-ness' [Devitt]
8. Modes of Existence / E. Nominalism / 1. Nominalism / b. Nominalism about universals
The particular/universal distinction is unhelpful clutter; we should accept 'a is F' as basic [Devitt]
8. Modes of Existence / E. Nominalism / 1. Nominalism / c. Nominalism about abstracta
Quineans take predication about objects as basic, not reference to properties they may have [Devitt]
9. Objects / D. Essence of Objects / 10. Essence as Species
Essentialism concerns the nature of a group, not its category [Devitt]
Things that gradually change, like species, can still have essences [Devitt]
12. Knowledge Sources / A. A Priori Knowledge / 4. A Priori as Necessities
Why should necessities only be knowable a priori? That Hesperus is Phosporus is known empirically [Devitt]
How could the mind have a link to the necessary character of reality? [Devitt]
12. Knowledge Sources / A. A Priori Knowledge / 9. A Priori from Concepts
We explain away a priori knowledge, not as directly empirical, but as indirectly holistically empirical [Devitt]
12. Knowledge Sources / A. A Priori Knowledge / 11. Denying the A Priori
The idea of the a priori is so obscure that it won't explain anything [Devitt]
Some knowledge must be empirical; naturalism implies that all knowledge is like that [Devitt]
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 / B. Natural Kinds / 1. Natural Kinds
Some kinds are very explanatory, but others less so, and some not at all [Devitt]
27. Natural Reality / G. Biology / 5. Species
We name species as small to share properties, but large enough to yield generalisations [Devitt]
Species are phenetic, biological, niche, or phylogenetic-cladistic [Devitt, by PG]
The higher categories are not natural kinds, so the Linnaean hierarchy should be given up [Devitt]
Species pluralism says there are several good accounts of what a species is [Devitt]