Combining Philosophers

All the ideas for Hermarchus, Brian Clegg and Jonathan D. Jacobs

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34 ideas

3. Truth / B. Truthmakers / 11. Truthmaking and Correspondence
Unlike correspondence, truthmaking can be one truth to many truthmakers, or vice versa [Jacobs]
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 / A. Relations / 3. Structural Relations
If structures result from intrinsic natures of properties, the 'relations' between them can drop out [Jacobs]
8. Modes of Existence / C. Powers and Dispositions / 1. Powers
Science aims at identifying the structure and nature of the powers that exist [Jacobs]
8. Modes of Existence / C. Powers and Dispositions / 2. Powers as Basic
Powers come from concrete particulars, not from the laws of nature [Jacobs]
10. Modality / A. Necessity / 10. Impossibility
Possibilities are manifestations of some power, and impossibilies rest on no powers [Jacobs]
10. Modality / B. Possibility / 1. Possibility
States of affairs are only possible if some substance could initiate a causal chain to get there [Jacobs]
10. Modality / B. Possibility / 9. Counterfactuals
Counterfactuals invite us to consider the powers picked out by the antecedent [Jacobs]
10. Modality / C. Sources of Modality / 1. Sources of Necessity
Possible worlds are just not suitable truthmakers for modality [Jacobs]
10. Modality / C. Sources of Modality / 5. Modality from Actuality
All modality is in the properties and relations of the actual world [Jacobs]
10. Modality / C. Sources of Modality / 6. Necessity from Essence
We can base counterfactuals on powers, not possible worlds, and hence define necessity [Jacobs]
10. Modality / E. Possible worlds / 1. Possible Worlds / c. Possible worlds realism
Concrete worlds, unlike fictions, at least offer evidence of how the actual world could be [Jacobs]
10. Modality / E. Possible worlds / 1. Possible Worlds / e. Against possible worlds
If some book described a possibe life for you, that isn't what makes such a life possible [Jacobs]
Possible worlds semantics gives little insight into modality [Jacobs]
25. Social Practice / F. Life Issues / 6. Animal Rights
Animals are dangerous and nourishing, and can't form contracts of justice [Hermarchus, by Sedley]