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All the ideas for 'works', 'A Mathematical Introduction to Logic (2nd)' and 'The Limits of Abstraction'

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71 ideas

1. Philosophy / A. Wisdom / 1. Nature of Wisdom
For Plato true wisdom is supernatural [Plato, by Weil]
     Full Idea: It is evident that Plato regards true wisdom as something supernatural.
     From: report of Plato (works [c.375 BCE]) by Simone Weil - God in Plato p.61
     A reaction: Taken literally, I assume this is wrong, but we can empathise with the thought. Wisdom has the feeling of rising above the level of mere knowledge, to achieve the overview I associate with philosophy.
1. Philosophy / C. History of Philosophy / 2. Ancient Philosophy / b. Pre-Socratic philosophy
Plato never mentions Democritus, and wished to burn his books [Plato, by Diog. Laertius]
     Full Idea: Plato, who mentions nearly all the ancient philosophers, nowhere speaks of Democritus; he wished to burn all of his books, but was persuaded that it was futile.
     From: report of Plato (works [c.375 BCE]) by Diogenes Laertius - Lives of Eminent Philosophers 09.7.8
2. Reason / C. Styles of Reason / 1. Dialectic
Two contradictories force us to find a relation which will correlate them [Plato, by Weil]
     Full Idea: Where contradictions appear there is a correlation of contraries, which is relation. If a contradiction is imposed on the intelligence, it is forced to think of a relation to transform the contradiction into a correlation, which draws the soul higher.
     From: report of Plato (works [c.375 BCE]) by Simone Weil - God in Plato p.70
     A reaction: A much better account of the dialectic than anything I have yet seen in Hegel. For the first time I see some sense in it. A contradiction is not a falsehood, and it must be addressed rather than side-stepped. A kink in the system, that needs ironing.
2. Reason / D. Definition / 3. Types of Definition
Implicit definitions must be satisfiable, creative definitions introduce things, contextual definitions build on things [Fine,K, by Cook/Ebert]
     Full Idea: Fine distinguishes 'implicit definitions', where we must know it is satisfiable before it is deployed, 'creative definitions', where objects are introduced in virtue of the definition, ..and 'contextual definitions', based on established vocabulary.
     From: report of Kit Fine (The Limits of Abstraction [2002], 060) by R Cook / P Ebert - Notice of Fine's 'Limits of Abstraction' 3
     A reaction: Fine is a fan of creative definition. This sounds something like the distinction between cutting nature at the perceived joints, and speculating about where new joints might be inserted. Quite a helpful thought.
'Creative definitions' do not presuppose the existence of the objects defined [Fine,K]
     Full Idea: What I call 'creative definitions' are made from a standpoint in which the existence of the objects that are to be assigned to the terms is not presupposed.
     From: Kit Fine (The Limits of Abstraction [2002], II.1)
4. Formal Logic / B. Propositional Logic PL / 3. Truth Tables
Until the 1960s the only semantics was truth-tables [Enderton]
     Full Idea: Until the 1960s standard truth-table semantics were the only ones that there were.
     From: Herbert B. Enderton (A Mathematical Introduction to Logic (2nd) [2001], 1.10.1)
     A reaction: The 1960s presumably marked the advent of possible worlds.
4. Formal Logic / F. Set Theory ST / 2. Mechanics of Set Theory / a. Symbols of ST
'dom R' indicates the 'domain' of objects having a relation [Enderton]
     Full Idea: 'dom R' indicates the 'domain' of a relation, that is, the set of all objects that are members of ordered pairs and that have that relation.
     From: Herbert B. Enderton (A Mathematical Introduction to Logic (2nd) [2001], Ch.0)
'fld R' indicates the 'field' of all objects in the relation [Enderton]
     Full Idea: 'fld R' indicates the 'field' of a relation, that is, the set of all objects that are members of ordered pairs on either side of the relation.
     From: Herbert B. Enderton (A Mathematical Introduction to Logic (2nd) [2001], Ch.0)
'ran R' indicates the 'range' of objects being related to [Enderton]
     Full Idea: 'ran R' indicates the 'range' of a relation, that is, the set of all objects that are members of ordered pairs and that are related to by the first objects.
     From: Herbert B. Enderton (A Mathematical Introduction to Logic (2nd) [2001], Ch.0)
We write F:A→B to indicate that A maps into B (the output of F on A is in B) [Enderton]
     Full Idea: We write F : A → B to indicate that A maps into B, that is, the domain of relating things is set A, and the things related to are all in B. If we add that F = B, then A maps 'onto' B.
     From: Herbert B. Enderton (A Mathematical Introduction to Logic (2nd) [2001], Ch.0)
'F(x)' is the unique value which F assumes for a value of x [Enderton]
     Full Idea: F(x) is a 'function', which indicates the unique value which y takes in ∈ F. That is, F(x) is the value y which F assumes at x.
     From: Herbert B. Enderton (A Mathematical Introduction to Logic (2nd) [2001], Ch.0)
4. Formal Logic / F. Set Theory ST / 2. Mechanics of Set Theory / b. Terminology of ST
A relation is 'symmetric' on a set if every ordered pair has the relation in both directions [Enderton]
     Full Idea: A relation is 'symmetric' on a set if every ordered pair in the set has the relation in both directions.
     From: Herbert B. Enderton (A Mathematical Introduction to Logic (2nd) [2001], Ch.0)
A relation is 'transitive' if it can be carried over from two ordered pairs to a third [Enderton]
     Full Idea: A relation is 'transitive' on a set if the relation can be carried over from two ordered pairs to a third.
     From: Herbert B. Enderton (A Mathematical Introduction to Logic (2nd) [2001], Ch.0)
The 'powerset' of a set is all the subsets of a given set [Enderton]
     Full Idea: The 'powerset' of a set is all the subsets of a given set. Thus: PA = {x : x ⊆ A}.
     From: Herbert B. Enderton (A Mathematical Introduction to Logic (2nd) [2001], Ch.0)
Two sets are 'disjoint' iff their intersection is empty [Enderton]
     Full Idea: Two sets are 'disjoint' iff their intersection is empty (i.e. they have no members in common).
     From: Herbert B. Enderton (A Mathematical Introduction to Logic (2nd) [2001], Ch.0)
A 'domain' of a relation is the set of members of ordered pairs in the relation [Enderton]
     Full Idea: The 'domain' of a relation is the set of all objects that are members of ordered pairs that are members of the relation.
     From: Herbert B. Enderton (A Mathematical Introduction to Logic (2nd) [2001], Ch.0)
A 'relation' is a set of ordered pairs [Enderton]
     Full Idea: A 'relation' is a set of ordered pairs. The ordering relation on the numbers 0-3 is captured by - in fact it is - the set of ordered pairs {<0,1>,<0,2>,<0,3>,<1,2>,<1,3>,<2,3>}.
     From: Herbert B. Enderton (A Mathematical Introduction to Logic (2nd) [2001], Ch.0)
     A reaction: This can't quite be a definition of order among numbers, since it relies on the notion of a 'ordered' pair.
A 'function' is a relation in which each object is related to just one other object [Enderton]
     Full Idea: A 'function' is a relation which is single-valued. That is, for each object, there is only one object in the function set to which that object is related.
     From: Herbert B. Enderton (A Mathematical Introduction to Logic (2nd) [2001], Ch.0)
A function 'maps A into B' if the relating things are set A, and the things related to are all in B [Enderton]
     Full Idea: A function 'maps A into B' if the domain of relating things is set A, and the things related to are all in B.
     From: Herbert B. Enderton (A Mathematical Introduction to Logic (2nd) [2001], Ch.0)
A function 'maps A onto B' if the relating things are set A, and the things related to are set B [Enderton]
     Full Idea: A function 'maps A onto B' if the domain of relating things is set A, and the things related to are set B.
     From: Herbert B. Enderton (A Mathematical Introduction to Logic (2nd) [2001], Ch.0)
A relation is 'reflexive' on a set if every member bears the relation to itself [Enderton]
     Full Idea: A relation is 'reflexive' on a set if every member of the set bears the relation to itself.
     From: Herbert B. Enderton (A Mathematical Introduction to Logic (2nd) [2001], Ch.0)
A relation satisfies 'trichotomy' if all pairs are either relations, or contain identical objects [Enderton]
     Full Idea: A relation satisfies 'trichotomy' on a set if every ordered pair is related (in either direction), or the objects are identical.
     From: Herbert B. Enderton (A Mathematical Introduction to Logic (2nd) [2001], Ch.0)
A set is 'dominated' by another if a one-to-one function maps the first set into a subset of the second [Enderton]
     Full Idea: A set is 'dominated' by another if a one-to-one function maps the first set into a subset of the second.
     From: Herbert B. Enderton (A Mathematical Introduction to Logic (2nd) [2001], Ch.0)
4. Formal Logic / F. Set Theory ST / 3. Types of Set / e. Equivalence classes
An 'equivalence relation' is a reflexive, symmetric and transitive binary relation [Enderton]
     Full Idea: An 'equivalence relation' is a binary relation which is reflexive, and symmetric, and transitive.
     From: Herbert B. Enderton (A Mathematical Introduction to Logic (2nd) [2001], Ch.0)
We 'partition' a set into distinct subsets, according to each relation on its objects [Enderton]
     Full Idea: Equivalence classes will 'partition' a set. That is, it will divide it into distinct subsets, according to each relation on the set.
     From: Herbert B. Enderton (A Mathematical Introduction to Logic (2nd) [2001], Ch.0)
5. Theory of Logic / A. Overview of Logic / 1. Overview of Logic
Inference not from content, but from the fact that it was said, is 'conversational implicature' [Enderton]
     Full Idea: The process is dubbed 'conversational implicature' when the inference is not from the content of what has been said, but from the fact that it has been said.
     From: Herbert B. Enderton (A Mathematical Introduction to Logic (2nd) [2001], 1.7.3)
5. Theory of Logic / B. Logical Consequence / 2. Types of Consequence
Validity is either semantic (what preserves truth), or proof-theoretic (following procedures) [Enderton]
     Full Idea: The point of logic is to give an account of the notion of validity,..in two standard ways: the semantic way says that a valid inference preserves truth (symbol |=), and the proof-theoretic way is defined in terms of purely formal procedures (symbol |-).
     From: Herbert B. Enderton (A Mathematical Introduction to Logic (2nd) [2001], 1.1.3..)
     A reaction: This division can be mirrored in mathematics, where it is either to do with counting or theorising about things in the physical world, or following sets of rules from axioms. Language can discuss reality, or play word-games.
5. Theory of Logic / I. Semantics of Logic / 3. Logical Truth
A logical truth or tautology is a logical consequence of the empty set [Enderton]
     Full Idea: A is a logical truth (tautology) (|= A) iff it is a semantic consequence of the empty set of premises (φ |= A), that is, every interpretation makes A true.
     From: Herbert B. Enderton (A Mathematical Introduction to Logic (2nd) [2001], 1.3.4)
     A reaction: So the final column of every line of the truth table will be T.
5. Theory of Logic / I. Semantics of Logic / 4. Satisfaction
A truth assignment to the components of a wff 'satisfy' it if the wff is then True [Enderton]
     Full Idea: A truth assignment 'satisfies' a formula, or set of formulae, if it evaluates as True when all of its components have been assigned truth values.
     From: Herbert B. Enderton (A Mathematical Introduction to Logic (2nd) [2001], 1.2)
     A reaction: [very roughly what Enderton says!] The concept becomes most significant when a large set of wff's is pronounced 'satisfied' after a truth assignment leads to them all being true.
5. Theory of Logic / K. Features of Logics / 3. Soundness
A proof theory is 'sound' if its valid inferences entail semantic validity [Enderton]
     Full Idea: If every proof-theoretically valid inference is semantically valid (so that |- entails |=), the proof theory is said to be 'sound'.
     From: Herbert B. Enderton (A Mathematical Introduction to Logic (2nd) [2001], 1.1.7)
5. Theory of Logic / K. Features of Logics / 4. Completeness
A proof theory is 'complete' if semantically valid inferences entail proof-theoretic validity [Enderton]
     Full Idea: If every semantically valid inference is proof-theoretically valid (so that |= entails |-), the proof-theory is said to be 'complete'.
     From: Herbert B. Enderton (A Mathematical Introduction to Logic (2nd) [2001], 1.1.7)
5. Theory of Logic / K. Features of Logics / 6. Compactness
Proof in finite subsets is sufficient for proof in an infinite set [Enderton]
     Full Idea: If a wff is tautologically implied by a set of wff's, it is implied by a finite subset of them; and if every finite subset is satisfiable, then so is the whole set of wff's.
     From: Herbert B. Enderton (A Mathematical Introduction to Logic (2nd) [2001], 2.5)
     A reaction: [Enderton's account is more symbolic] He adds that this also applies to models. It is a 'theorem' because it can be proved. It is a major theorem in logic, because it brings the infinite under control, and who doesn't want that?
5. Theory of Logic / K. Features of Logics / 7. Decidability
Expressions are 'decidable' if inclusion in them (or not) can be proved [Enderton]
     Full Idea: A set of expressions is 'decidable' iff there exists an effective procedure (qv) that, given some expression, will decide whether or not the expression is included in the set (i.e. doesn't contradict it).
     From: Herbert B. Enderton (A Mathematical Introduction to Logic (2nd) [2001], 1.7)
     A reaction: This is obviously a highly desirable feature for a really reliable system of expressions to possess. All finite sets are decidable, but some infinite sets are not.
5. Theory of Logic / K. Features of Logics / 8. Enumerability
For a reasonable language, the set of valid wff's can always be enumerated [Enderton]
     Full Idea: The Enumerability Theorem says that for a reasonable language, the set of valid wff's can be effectively enumerated.
     From: Herbert B. Enderton (A Mathematical Introduction to Logic (2nd) [2001], 2.5)
     A reaction: There are criteria for what makes a 'reasonable' language (probably specified to ensure enumerability!). Predicates and functions must be decidable, and the language must be finite.
7. Existence / A. Nature of Existence / 4. Abstract Existence
Abstracts cannot be identified with sets [Fine,K]
     Full Idea: It is impossible for a proponent of both sets and abstracts to identify the abstracts, in any reasonable manner, with the sets.
     From: Kit Fine (The Limits of Abstraction [2002], IV.1)
     A reaction: [This observation emerges from a proof Fine has just completed] Cf Idea 10137. The implication is that there is no compromise view available, and one must choose between abstraction or sets as one's account of numbers and groups of concepts.
Points in Euclidean space are abstract objects, but not introduced by abstraction [Fine,K]
     Full Idea: Points in abstract Euclidean space are abstract objects, and yet are not objects of abstraction, since they are not introduced through a principle of abstraction of the sort envisaged by Frege.
     From: Kit Fine (The Limits of Abstraction [2002], I.1)
     A reaction: The point seems to be that they are not abstracted 'from' anything, but are simpy posited as basic constituents. I suggest that points are idealisations (of smallness) rather than abstractions. They are idealised 'from' substances.
Postulationism says avoid abstract objects by giving procedures that produce truth [Fine,K]
     Full Idea: A procedural form of postulationism says that instead of stipulating that certain statements are true, one specifies certain procedures for extending the domain to one in which the statement will in fact be true, without invoking an abstract ontology.
     From: Kit Fine (The Limits of Abstraction [2002], II.5)
     A reaction: The whole of philosophy might go better if it was founded on procedures and processes, rather than on objects. The Hopi Indians were right.
8. Modes of Existence / A. Relations / 3. Structural Relations
Plato's idea of 'structure' tends to be mathematically expressed [Plato, by Koslicki]
     Full Idea: 'Structure' tends to be characterized by Plato as something that is mathematically expressed.
     From: report of Plato (works [c.375 BCE]) by Kathrin Koslicki - The Structure of Objects V.3 iv
     A reaction: [Koslicki is drawing on Verity Harte here]
8. Modes of Existence / D. Universals / 6. Platonic Forms / a. Platonic Forms
Plato's Forms meant that the sophists only taught the appearance of wisdom and virtue [Plato, by Nehamas]
     Full Idea: Plato's theory of Forms allowed him to claim that the sophists and other opponents were trapped in the world of appearance. What they therefore taught was only apparent wisdom and virtue.
     From: report of Plato (works [c.375 BCE]) by Alexander Nehamas - Eristic,Antilogic,Sophistic,Dialectic p.118
Platonists argue for the indivisible triangle-in-itself [Plato, by Aristotle]
     Full Idea: The Platonists, on the basis of purely logical arguments, posit the existence of an indivisible 'triangle in itself'.
     From: report of Plato (works [c.375 BCE]) by Aristotle - Coming-to-be and Passing-away (Gen/Corr) 316a15
     A reaction: A helpful confirmation that geometrical figures really are among the Forms (bearing in mind that numbers are not, because they contain one another). What shape is the Form of the triangle?
When Diogenes said he could only see objects but not their forms, Plato said it was because he had eyes but no intellect [Plato, by Diog. Laertius]
     Full Idea: When Diogenes told Plato he saw tables and cups, but not 'tableness' and 'cupness', Plato replied that this was because Diogenes had eyes but no intellect.
     From: report of Plato (works [c.375 BCE]) by Diogenes Laertius - Lives of Eminent Philosophers 06.2.6
8. Modes of Existence / D. Universals / 6. Platonic Forms / b. Partaking
If there is one Form for both the Form and its participants, they must have something in common [Aristotle on Plato]
     Full Idea: If there is the same Form for the Forms and for their participants, then they must have something in common.
     From: comment on Plato (works [c.375 BCE]) by Aristotle - Metaphysics 991a
8. Modes of Existence / D. Universals / 6. Platonic Forms / c. Self-predication
If gods are like men, they are just eternal men; similarly, Forms must differ from particulars [Aristotle on Plato]
     Full Idea: We say there is the form of man, horse and health, but nothing else, making the same mistake as those who say that there are gods but that they are in the form of men. They just posit eternal men, and here we are not positing forms but eternal sensibles.
     From: comment on Plato (works [c.375 BCE]) by Aristotle - Metaphysics 997b
8. Modes of Existence / D. Universals / 6. Platonic Forms / d. Forms critiques
A Form is a cause of things only in the way that white mixed with white is a cause [Aristotle on Plato]
     Full Idea: A Form is a cause of things only in the way that white mixed with white is a cause.
     From: comment on Plato (works [c.375 BCE]) by Aristotle - Metaphysics 991a
The Forms cannot be changeless if they are in changing things [Aristotle on Plato]
     Full Idea: The Forms could not be changeless if they were in changing things.
     From: comment on Plato (works [c.375 BCE]) by Aristotle - Metaphysics 998a
9. Objects / A. Existence of Objects / 2. Abstract Objects / a. Nature of abstracta
The greatest discovery in human thought is Plato's discovery of abstract objects [Brown,JR on Plato]
     Full Idea: The greatest discovery in the history of human thought is Plato's discovery of abstract objects.
     From: comment on Plato (works [c.375 BCE]) by James Robert Brown - Philosophy of Mathematics Ch. 2
     A reaction: Compare Idea 2860! Given the diametrically opposed views, it is clearly likely that Plato's central view is the most important idea in the history of human thought, even if it is wrong.
9. Objects / A. Existence of Objects / 5. Individuation / a. Individuation
We can grasp whole things in science, because they have a mathematics and a teleology [Plato, by Koslicki]
     Full Idea: Due to the mathematical nature of structure and the teleological cause underlying the creation of Platonic wholes, these wholes are intelligible, and are in fact the proper objects of science.
     From: report of Plato (works [c.375 BCE]) by Kathrin Koslicki - The Structure of Objects 5.3
     A reaction: I like this idea, because it pays attention to the connection between how we conceive objects to be, and how we are able to think about objects. Only examining these two together enables us to grasp metaphysics.
9. Objects / B. Unity of Objects / 1. Unifying an Object / a. Intrinsic unification
Plato sees an object's structure as expressible in mathematics [Plato, by Koslicki]
     Full Idea: The 'structure' of an object tends to be characterised by Plato as something that is mathematically expressible.
     From: report of Plato (works [c.375 BCE]) by Kathrin Koslicki - The Structure of Objects 5.3
     A reaction: This seems to be pure Pythagoreanism (see Idea 644). Plato is pursuing Pythagoras's research programme, of trying to find mathematics buried in every aspect of reality.
Plato was less concerned than Aristotle with the source of unity in a complex object [Plato, by Koslicki]
     Full Idea: Plato was less concerned than Aristotle with the project of how to account, in completely general terms, for the source of unity within a mereologically complex object.
     From: report of Plato (works [c.375 BCE]) by Kathrin Koslicki - The Structure of Objects 5.5
     A reaction: Plato seems to have simply asserted that some sort of harmony held things together. Aristotles puts the forms [eidos] within objects, rather than external, so he has to give a fuller account of what is going on in an object. He never managed it!
9. Objects / B. Unity of Objects / 2. Substance / c. Types of substance
Plato's holds that there are three substances: Forms, mathematical entities, and perceptible bodies [Plato, by Aristotle]
     Full Idea: Plato's doctrine was that the Forms and mathematicals are two substances and that the third substance is that of perceptible bodies.
     From: report of Plato (works [c.375 BCE]) by Aristotle - Metaphysics 1028b
9. Objects / C. Structure of Objects / 8. Parts of Objects / c. Wholes from parts
Plato says wholes are either containers, or they're atomic, or they don't exist [Plato, by Koslicki]
     Full Idea: Plato considers a 'container' model for wholes (which are disjoint from their parts) [Parm 144e3-], and a 'nihilist' model, in which only wholes are mereological atoms, and a 'bare pluralities' view, in which wholes are not really one at all.
     From: report of Plato (works [c.375 BCE]) by Kathrin Koslicki - The Structure of Objects 5.2
     A reaction: [She cites Verity Harte for this analysis of Plato] The fourth, and best, seems to be that wholes are parts which fall under some unifying force or structure or principle.
9. Objects / D. Essence of Objects / 2. Types of Essence
Only universals have essence [Plato, by Politis]
     Full Idea: Plato argues that only universals have essence.
     From: report of Plato (works [c.375 BCE]) by Vassilis Politis - Aristotle and the Metaphysics 1.4
9. Objects / D. Essence of Objects / 6. Essence as Unifier
Plato and Aristotle take essence to make a thing what it is [Plato, by Politis]
     Full Idea: Plato and Aristotle have a shared general conception of essence: the essence of a thing is what that thing is simply in virtue of itself and in virtue of being the very thing it is. It answers the question 'What is this very thing?'
     From: report of Plato (works [c.375 BCE]) by Vassilis Politis - Aristotle and the Metaphysics 1.4
10. Modality / B. Possibility / 8. Conditionals / f. Pragmatics of conditionals
Sentences with 'if' are only conditionals if they can read as A-implies-B [Enderton]
     Full Idea: Not all sentences using 'if' are conditionals. Consider 'if you want a banana, there is one in the kitchen'. The rough test is that a conditional can be rewritten as 'that A implies that B'.
     From: Herbert B. Enderton (A Mathematical Introduction to Logic (2nd) [2001], 1.6.4)
14. Science / D. Explanation / 1. Explanation / b. Aims of explanation
A good explanation totally rules out the opposite explanation (so Forms are required) [Plato, by Ruben]
     Full Idea: For Plato, an acceptable explanation is one such that there is no possibility of there being the opposite explanation at all, and he thought that only explanations in terms of the Forms, but never physical explanations, could meet this requirement.
     From: report of Plato (works [c.375 BCE]) by David-Hillel Ruben - Explaining Explanation Ch 2
     A reaction: [Republic 436c is cited]
18. Thought / A. Modes of Thought / 3. Emotions / g. Controlling emotions
Plato wanted to somehow control and purify the passions [Vlastos on Plato]
     Full Idea: Plato put high on his agenda a project which did not figure in Socrates' programme at all: the hygienic conditioning of the passions. This cannot be an intellectual process, as argument cannot touch them.
     From: comment on Plato (works [c.375 BCE]) by Gregory Vlastos - Socrates: Ironist and Moral Philosopher p.88
     A reaction: This is the standard traditional view of any thinker who exaggerates the importance and potential of reason in our lives.
18. Thought / E. Abstraction / 1. Abstract Thought
Fine's 'procedural postulationism' uses creative definitions, but avoids abstract ontology [Fine,K, by Cook/Ebert]
     Full Idea: Fine says creative definitions can found mathematics. His 'procedural postulationism' says one stipulates not truths, but certain procedures for extending a domain. The procedures can be stated without invoking an abstract ontology.
     From: report of Kit Fine (The Limits of Abstraction [2002], 100) by R Cook / P Ebert - Notice of Fine's 'Limits of Abstraction' 4
     A reaction: (For creative definitions, see Idea 9143) This sounds close in spirit to fictionalism, but with the emphasis on the procedure (which can presumably be formalized) rather than a pure act of imaginative creation.
18. Thought / E. Abstraction / 2. Abstracta by Selection
Many different kinds of mathematical objects can be regarded as forms of abstraction [Fine,K]
     Full Idea: Many different kinds of mathematical objects (natural numbers, the reals, points, lines, figures, groups) can be regarded as forms of abstraction, with special theories having their basis in a general theory of abstraction.
     From: Kit Fine (The Limits of Abstraction [2002], I.4)
     A reaction: This result, if persuasive, would be just the sort of unified account which the whole problem of abstact ideas requires.
18. Thought / E. Abstraction / 7. Abstracta by Equivalence
We can abstract from concepts (e.g. to number) and from objects (e.g. to direction) [Fine,K]
     Full Idea: A principle of abstraction is 'conceptual' when the items upon which it abstracts are concepts (e.g. a one-one correspondence associated with a number), and 'objectual' if they are objects (parallel lines associated with a direction).
     From: Kit Fine (The Limits of Abstraction [2002], I)
Fine considers abstraction as reconceptualization, to produce new senses by analysing given senses [Fine,K, by Cook/Ebert]
     Full Idea: Fine considers abstraction principles as instances of reconceptualization (rather than implicit definition, or using the Context Principle). This centres not on reference, but on new senses emerging from analysis of a given sense.
     From: report of Kit Fine (The Limits of Abstraction [2002], 035) by R Cook / P Ebert - Notice of Fine's 'Limits of Abstraction' 2
     A reaction: Fine develops an argument against this view, because (roughly) the procedure does not end in a unique result. Intuitively, the idea that abstraction is 'reconceptualization' sounds quite promising to me.
Abstractionism can be regarded as an alternative to set theory [Fine,K]
     Full Idea: The uncompromising abstractionist rejects set theory, seeing the theory of abstractions as an alternative, rather than as a supplement, to the standard theory of sets.
     From: Kit Fine (The Limits of Abstraction [2002], I.1)
     A reaction: There is also a 'compromising' version. Presumably you still have equivalence classes to categorise the objects, which are defined by their origin rather than by what they are members of... Cf. Idea 10145.
An object is the abstract of a concept with respect to a relation on concepts [Fine,K]
     Full Idea: We can see an object as being the abstract of a concept with respect to a relation on concepts. For example, we may say that 0 is the abstract of the empty concept with respect to the relation of one-one correspondence.
     From: Kit Fine (The Limits of Abstraction [2002], I.2)
     A reaction: This is Fine's attempt to give a modified account of the Fregean approach to abstraction. He says that the reference to a relation will solve the problem of identity between abstractions.
19. Language / F. Communication / 1. Rhetoric
Plato's whole philosophy may be based on being duped by reification - a figure of speech [Benardete,JA on Plato]
     Full Idea: Plato is liable to the charge of having been duped by a figure of speech, albeit the most profound of all, the trope of reification.
     From: comment on Plato (works [c.375 BCE]) by José A. Benardete - Metaphysics: the logical approach Ch.12
     A reaction: That might be a plausible account if his view was ridiculous, but given how many powerful friends Plato has, especially in the philosophy of mathematics, we should assume he was cleverer than that.
22. Metaethics / A. Ethics Foundations / 2. Source of Ethics / c. Ethical intuitionism
Plato never refers to examining the conscience [Plato, by Foucault]
     Full Idea: Plato never speaks of the examination of conscience - never!
     From: report of Plato (works [c.375 BCE]) by Michel Foucault - On the Genealogy of Ethics p.276
     A reaction: Plato does imply some sort of self-evident direct knowledge about that nature of a healthy soul. Presumably the full-blown concept of conscience is something given from outside, from God. In 'Euthyphro', Plato asserts the primacy of morality (Idea 337).
22. Metaethics / A. Ethics Foundations / 2. Source of Ethics / j. Ethics by convention
As religion and convention collapsed, Plato sought morals not just in knowledge, but in the soul [Williams,B on Plato]
     Full Idea: Once gods and fate and social expectation were no longer there, Plato felt it necessary to discover ethics inside human nature, not just as ethical knowledge (Socrates' view), but in the structure of the soul.
     From: comment on Plato (works [c.375 BCE]) by Bernard Williams - Shame and Necessity II - p.43
     A reaction: anti Charles Taylor
22. Metaethics / C. The Good / 1. Goodness / b. Types of good
Plato's legacy to European thought was the Good, the Beautiful and the True [Plato, by Gray]
     Full Idea: Plato's legacy to European thought was a trio of capital letters - the Good, the Beautiful and the True.
     From: report of Plato (works [c.375 BCE]) by John Gray - Straw Dogs 2.8
     A reaction: It seems to have been Baumgarten who turned this into a slogan (Idea 8117). Gray says these ideals are lethal, but I identify with them very strongly, and am quite happy to see the good life as an attempt to find the right balance between them.
22. Metaethics / C. The Good / 1. Goodness / f. Good as pleasure
Pleasure is better with the addition of intelligence, so pleasure is not the good [Plato, by Aristotle]
     Full Idea: Plato says the life of pleasure is more desirable with the addition of intelligence, and if the combination is better, pleasure is not the good.
     From: report of Plato (works [c.375 BCE]) by Aristotle - Nicomachean Ethics 1172b27
     A reaction: It is obvious why we like pleasure, but not why intelligence makes it 'better'. Maybe it is just because we enjoy intelligence?
22. Metaethics / C. The Good / 2. Happiness / d. Routes to happiness
Plato decided that the virtuous and happy life was the philosophical life [Plato, by Nehamas]
     Full Idea: Plato came to the conclusion that virtue and happiness consist in the life of philosophy itself.
     From: report of Plato (works [c.375 BCE]) by Alexander Nehamas - Eristic,Antilogic,Sophistic,Dialectic p.117
     A reaction: This view is obviously ridiculous, because it largely excludes almost the entire human race, which sees philosophy as a cul-de-sac, even if it is good. But virtue and happiness need some serious thought.
23. Ethics / C. Virtue Theory / 1. Virtue Theory / a. Nature of virtue
Plato, unusually, said that theoretical and practical wisdom are inseparable [Plato, by Kraut]
     Full Idea: Two virtues that are ordinarily kept distinct - theoretical and practical wisdom - are joined by Plato; he thinks that neither one can be fully possessed unless it is combined with the other.
     From: report of Plato (works [c.375 BCE]) by Richard Kraut - Plato
     A reaction: I get the impression that this doctrine comes from Socrates, whose position is widely reported as 'intellectualist'. Aristotle certainly held the opposite view.
23. Ethics / F. Existentialism / 4. Boredom
Plato is boring [Nietzsche on Plato]
     Full Idea: Plato is boring.
     From: comment on Plato (works [c.375 BCE]) by Friedrich Nietzsche - Twilight of the Idols 9.2
27. Natural Reality / D. Time / 3. Parts of Time / a. Beginning of time
Almost everyone except Plato thinks that time could not have been generated [Plato, by Aristotle]
     Full Idea: With a single exception (Plato) everyone agrees about time - that it is not generated. Democritus says time is an obvious example of something not generated.
     From: report of Plato (works [c.375 BCE]) by Aristotle - Physics 251b14