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53 ideas

1. Philosophy / F. Analytic Philosophy / 2. Analysis by Division
Begin examination with basics, and subdivide till you can go no further [Aristotle]
     Full Idea: The examination must be carried on and begin from the primary classes and then go on step by step until further division is impossible.
     From: Aristotle (Topics [c.331 BCE], 109b17)
     A reaction: This is a good slogan for the analytic approach to thought. I take Aristotle (or possibly Socrates) to be the father of analysis, not Frege (though see Idea 9840). (He may be thinking of the tableau method of proof).
2. Reason / C. Styles of Reason / 1. Dialectic
Dialectic starts from generally accepted opinions [Aristotle]
     Full Idea: Reasoning is dialectical which reasons from generally accepted opinions.
     From: Aristotle (Topics [c.331 BCE], 100a30)
     A reaction: This is right at the heart of Aristotle's philosophical method, and Greek thinking generally. There are nice modern debates about 'folk' understanding, derived from science (e.g. quantum theory) which suggest that starting from normal views is a bad idea.
2. Reason / D. Definition / 1. Definitions
There can't be one definition of two things, or two definitions of the same thing [Aristotle]
     Full Idea: There cannot possibly be one definition of two things, or two definitions of the same thing.
     From: Aristotle (Topics [c.331 BCE], 154a11)
     A reaction: The second half of this is much bolder and more controversial, and plenty of modern thinkers would flatly reject it. Are definitions contextual, that is, designed for some specific human purpose. Must definitions be of causes?
Definitions are easily destroyed, since they can contain very many assertions [Aristotle]
     Full Idea: A definition is the easiest of all things to destroy; for, since it contains many assertions, the opportunities which it offers are very numerous, and the more abundant the material, the more quickly the reasoning can set to work.
     From: Aristotle (Topics [c.331 BCE], 155a03)
     A reaction: I quote this to show that Aristotle expected many definitions to be very long affairs (maybe even of book length?)
2. Reason / D. Definition / 5. Genus and Differentia
We describe the essence of a particular thing by means of its differentiae [Aristotle]
     Full Idea: We usually isolate the appropriate description of the essence of a particular thing by means of the differentiae which are peculiar to it.
     From: Aristotle (Topics [c.331 BCE], 108b05)
     A reaction: I take this to be important for showing the definition is more than mere categorisation. A good definition homes in the particular, by gradually narrowing down the differentiae.
The differentia indicate the qualities, but not the essence [Aristotle]
     Full Idea: No differentia indicates the essence [ti estin], but rather some quality, such as 'pedestrian' or 'biped'.
     From: Aristotle (Topics [c.331 BCE], 122b17)
     A reaction: We must disentangle this, since essence is what is definable, and definition seems to give us the essence, and yet it appears that definition only requires genus and differentia. Differentiae seem to be both generic and fine-grained. See Idea 12280!
In definitions the first term to be assigned ought to be the genus [Aristotle]
     Full Idea: In definitions the first term to be assigned ought to be the genus.
     From: Aristotle (Topics [c.331 BCE], 132a12)
     A reaction: We mustn't be deluded into thinking that nothing else is required. I take the increasing refinement of differentiae to be where the real action is. The genus gives you 70% of the explanation.
The genera and the differentiae are part of the essence [Aristotle]
     Full Idea: The genera and the differentiae are predicated in the category of essence.
     From: Aristotle (Topics [c.331 BCE], 153a19)
     A reaction: The definition is words, and the essence is real, so our best definition might not fully attain to the essence. Aristotle has us reaching out to the world through our definitions.
Differentia are generic, and belong with genus [Aristotle]
     Full Idea: The differentia, being generic in character, should be ranged with the genus.
     From: Aristotle (Topics [c.331 BCE], 101b18)
     A reaction: This does not mean that naming the differentia amounts to mere classification. I presume we can only state individual differences by using a language which is crammed full of universals.
'Genus' is part of the essence shared among several things [Aristotle]
     Full Idea: A 'genus' is that which is predicated in the category of essence of several things which differ in kind.
     From: Aristotle (Topics [c.331 BCE], 102a32)
     A reaction: Hence a genus is likely to be expressed by a universal, a one-over-many. A particular will be a highly individual collection of various genera, but what ensures the uniqueness of each thing, if they are indiscernible?
2. Reason / D. Definition / 6. Definition by Essence
The definition is peculiar to one thing, not common to many [Aristotle]
     Full Idea: The definition ought to be peculiar to one thing, not common to many.
     From: Aristotle (Topics [c.331 BCE], 149b24)
     A reaction: I take this to be very important, against those who think that definition is no more than mere categorisation. To explain, you must get down to the level of the individual. We must explain that uniquely docile tiger.
3. Truth / F. Semantic Truth / 2. Semantic Truth
While true-in-a-model seems relative, true-in-all-models seems not to be [Reck/Price]
     Full Idea: While truth can be defined in a relative way, as truth in one particular model, a non-relative notion of truth is implied, as truth in all models.
     From: E Reck / M Price (Structures and Structuralism in Phil of Maths [2000], §4)
     A reaction: [The article is actually discussing arithmetic] This idea strikes me as extremely important. True-in-all-models is usually taken to be tautological, but it does seem to give a more universal notion of truth. See semantic truth, Tarski, Davidson etc etc.
4. Formal Logic / F. Set Theory ST / 4. Axioms for Sets / a. Axioms for sets
ZFC set theory has only 'pure' sets, without 'urelements' [Reck/Price]
     Full Idea: In standard ZFC ('Zermelo-Fraenkel with Choice') set theory we deal merely with pure sets, not with additional urelements.
     From: E Reck / M Price (Structures and Structuralism in Phil of Maths [2000], §2)
     A reaction: The 'urelements' would the actual objects that are members of the sets, be they physical or abstract. This idea is crucial to understanding philosophy of mathematics, and especially logicism. Must the sets exist, just as the urelements do?
5. Theory of Logic / G. Quantification / 5. Second-Order Quantification
Three types of variable in second-order logic, for objects, functions, and predicates/sets [Reck/Price]
     Full Idea: In second-order logic there are three kinds of variables, for objects, for functions, and for predicates or sets.
     From: E Reck / M Price (Structures and Structuralism in Phil of Maths [2000], §5)
     A reaction: It is interesting that a predicate seems to be the same as a set, which begs rather a lot of questions. For those who dislike second-order logic, there seems nothing instrinsically wicked in having variables ranging over innumerable multi-order types.
5. Theory of Logic / L. Paradox / 2. Aporiai
Puzzles arise when reasoning seems equal on both sides [Aristotle]
     Full Idea: The equality of opposite reasonings is the cause of aporia; for it is when we reason on both [sides of a question] and it appears to us that everything can come about either way, that we are in a state of aporia about which of the two ways to take up.
     From: Aristotle (Topics [c.331 BCE], 145b17), quoted by Vassilis Politis - Aristotle and the Metaphysics 3.1
     A reaction: Other philosophers give up on the subject in this situation, but I love Aristotle because he takes this to be the place where philosophy begins.
6. Mathematics / A. Nature of Mathematics / 3. Nature of Numbers / g. Real numbers
'Analysis' is the theory of the real numbers [Reck/Price]
     Full Idea: 'Analysis' is the theory of the real numbers.
     From: E Reck / M Price (Structures and Structuralism in Phil of Maths [2000], §2)
     A reaction: 'Analysis' began with the infinitesimal calculus, which later built on the concept of 'limit'. A continuum of numbers seems to be required to make that work.
6. Mathematics / A. Nature of Mathematics / 4. Using Numbers / a. Units
Unit is the starting point of number [Aristotle]
     Full Idea: They say that the unit [monada] is the starting point of number (and the point the starting-point of a line).
     From: Aristotle (Topics [c.331 BCE], 108b30)
     A reaction: Yes, despite Frege's objections in the early part of the 'Grundlagen' (1884). I take arithmetic to be rooted in counting, despite all abstract definitions of number by Frege and Dedekind. Identity gives the unit, which is countable. See also Topics 141b9
6. Mathematics / B. Foundations for Mathematics / 4. Axioms for Number / a. Axioms for numbers
Mereological arithmetic needs infinite objects, and function definitions [Reck/Price]
     Full Idea: The difficulties for a nominalistic mereological approach to arithmetic is that an infinity of physical objects are needed (space-time points? strokes?), and it must define functions, such as 'successor'.
     From: E Reck / M Price (Structures and Structuralism in Phil of Maths [2000], §4)
     A reaction: Many ontologically austere accounts of arithmetic are faced with the problem of infinity. The obvious non-platonist response seems to be a modal or if-then approach. To postulate infinite abstract or physical entities so that we can add 3 and 2 is mad.
6. Mathematics / B. Foundations for Mathematics / 4. Axioms for Number / e. Peano arithmetic 2nd-order
Peano Arithmetic can have three second-order axioms, plus '1' and 'successor' [Reck/Price]
     Full Idea: A common formulation of Peano Arithmetic uses 2nd-order logic, the constant '1', and a one-place function 's' ('successor'). Three axioms then give '1 is not a successor', 'different numbers have different successors', and induction.
     From: E Reck / M Price (Structures and Structuralism in Phil of Maths [2000], §2)
     A reaction: This is 'second-order' Peano Arithmetic, though it is at least as common to formulate in first-order terms (only quantifying over objects, not over properties - as is done here in the induction axiom). I like the use of '1' as basic instead of '0'!
6. Mathematics / B. Foundations for Mathematics / 6. Mathematics as Set Theory / a. Mathematics is set theory
Set-theory gives a unified and an explicit basis for mathematics [Reck/Price]
     Full Idea: The merits of basing an account of mathematics on set theory are that it allows for a comprehensive unified treatment of many otherwise separate branches of mathematics, and that all assumption, including existence, are explicit in the axioms.
     From: E Reck / M Price (Structures and Structuralism in Phil of Maths [2000], §4)
     A reaction: I am forming the impression that set-theory provides one rather good model (maybe the best available) for mathematics, but that doesn't mean that mathematics is set-theory. The best map of a landscape isn't a landscape.
6. Mathematics / B. Foundations for Mathematics / 7. Mathematical Structuralism / a. Structuralism
Structuralism emerged from abstract algebra, axioms, and set theory and its structures [Reck/Price]
     Full Idea: Structuralism has emerged from the development of abstract algebra (such as group theory), the creation of axiom systems, the introduction of set theory, and Bourbaki's encyclopaedic survey of set theoretic structures.
     From: E Reck / M Price (Structures and Structuralism in Phil of Maths [2000], §2)
     A reaction: In other words, mathematics has gradually risen from one level of abstraction to the next, so that mathematical entities like points and numbers receive less and less attention, with relationships becoming more prominent.
6. Mathematics / B. Foundations for Mathematics / 7. Mathematical Structuralism / b. Varieties of structuralism
Relativist Structuralism just stipulates one successful model as its arithmetic [Reck/Price]
     Full Idea: Relativist Structuralism simply picks one particular model of axiomatised arithmetic (i.e. one particular interpretation that satisfies the axioms), and then stipulates what the elements, functions and quantifiers refer to.
     From: E Reck / M Price (Structures and Structuralism in Phil of Maths [2000], §4)
     A reaction: The point is that a successful model can be offered, and it doesn't matter which one, like having any sort of aeroplane, as long as it flies. I don't find this approach congenial, though having a model is good. What is the essence of flight?
There are 'particular' structures, and 'universal' structures (what the former have in common) [Reck/Price]
     Full Idea: The term 'structure' has two uses in the literature, what can be called 'particular structures' (which are particular relational systems), but also what can be called 'universal structures' - what particular systems share, or what they instantiate.
     From: E Reck / M Price (Structures and Structuralism in Phil of Maths [2000], §6)
     A reaction: This is a very helpful distinction, because it clarifies why (rather to my surprise) some structuralists turn out to be platonists in a new guise. Personal my interest in structuralism has been anti-platonist from the start.
Pattern Structuralism studies what isomorphic arithmetic models have in common [Reck/Price]
     Full Idea: According to 'pattern' structuralism, what we study are not the various particular isomorphic models of arithmetic, but something in addition to them: a corresponding pattern.
     From: E Reck / M Price (Structures and Structuralism in Phil of Maths [2000], §7)
     A reaction: Put like that, we have to feel a temptation to wield Ockham's Razor. It's bad enough trying to give the structure of all the isomorphic models, without seeking an even more abstract account of underlying patterns. But patterns connect to minds..
There are Formalist, Relativist, Universalist and Pattern structuralism [Reck/Price]
     Full Idea: There are four main variants of structuralism in the philosophy of mathematics - formalist structuralism, relativist structuralism, universalist structuralism (with modal variants), and pattern structuralism.
     From: E Reck / M Price (Structures and Structuralism in Phil of Maths [2000], §9)
     A reaction: I'm not sure where Chihara's later book fits into this, though it is at the nominalist end of the spectrum. Shapiro and Resnik do patterns (the latter more loosely); Hellman does modal universalism; Quine does the relativist version. Dedekind?
6. Mathematics / B. Foundations for Mathematics / 7. Mathematical Structuralism / c. Nominalist structuralism
Formalist Structuralism says the ontology is vacuous, or formal, or inference relations [Reck/Price]
     Full Idea: Formalist Structuralism endorses structural methodology in mathematics, but rejects semantic and metaphysical problems as either meaningless, or purely formal, or as inference relations.
     From: E Reck / M Price (Structures and Structuralism in Phil of Maths [2000], §3)
     A reaction: [very compressed] I find the third option fairly congenial, certainly in preference to rather platonist accounts of structuralism. One still needs to distinguish the mathematical from the non-mathematical in the inference relations.
Maybe we should talk of an infinity of 'possible' objects, to avoid arithmetic being vacuous [Reck/Price]
     Full Idea: It is tempting to take a modal turn, and quantify over all possible objects, because if there are only a finite number of actual objects, then there are no models (of the right sort) for Peano Arithmetic, and arithmetic is vacuously true.
     From: E Reck / M Price (Structures and Structuralism in Phil of Maths [2000], §5)
     A reaction: [compressed; Geoffrey Hellman is the chief champion of this view] The article asks whether we are not still left with the puzzle of whether infinitely many objects are possible, instead of existent.
6. Mathematics / B. Foundations for Mathematics / 7. Mathematical Structuralism / d. Platonist structuralism
Universalist Structuralism is based on generalised if-then claims, not one particular model [Reck/Price]
     Full Idea: Universalist Structuralism is a semantic thesis, that an arithmetical statement asserts a universal if-then statement. We build an if-then statement (using quantifiers) into the structure, and we generalise away from any one particular model.
     From: E Reck / M Price (Structures and Structuralism in Phil of Maths [2000], §5)
     A reaction: There remains the question of what is distinctively mathematical about the highly generalised network of inferences that is being described. Presumable the axioms capture that, but why those particular axioms? Russell is cited as an originator.
Universalist Structuralism eliminates the base element, as a variable, which is then quantified out [Reck/Price]
     Full Idea: Universalist Structuralism is eliminativist about abstract objects, in a distinctive form. Instead of treating the base element (say '1') as an ambiguous referring expression (the Relativist approach), it is a variable which is quantified out.
     From: E Reck / M Price (Structures and Structuralism in Phil of Maths [2000], §5)
     A reaction: I am a temperamental eliminativist on this front (and most others) so this is tempting. I am also in love with the concept of a 'variable', which I take to be utterly fundamental to all conceptual thought, even in animals, and not just a trick of algebra.
6. Mathematics / B. Foundations for Mathematics / 7. Mathematical Structuralism / e. Structuralism critique
The existence of an infinite set is assumed by Relativist Structuralism [Reck/Price]
     Full Idea: Relativist Structuralism must first assume the existence of an infinite set, otherwise there would be no model to pick, and arithmetical terms would have no reference.
     From: E Reck / M Price (Structures and Structuralism in Phil of Maths [2000], §4)
     A reaction: See Idea 10169 for Relativist Structuralism. They point out that ZFC has an Axiom of Infinity.
7. Existence / E. Categories / 3. Proposed Categories
There are ten categories: essence, quantity, quality, relation, place, time, position, state, activity, passivity [Aristotle]
     Full Idea: The four main types of predicates fall into ten categories: essence, quantity, quality, relation, place, time, position, state, activity, passivity.
     From: Aristotle (Topics [c.331 BCE], 103b20)
     A reaction: These are the standard ten categories of Aristotle. He is notable for the divisions not being sharp, and ten being a rough total. He is well aware of the limits of precision in such matters.
8. Modes of Existence / B. Properties / 1. Nature of Properties
An individual property has to exist (in past, present or future) [Aristotle]
     Full Idea: If it does not at present exist, or, if it has not existed in the past, or if it is not going to exist in the future, it will not be a property [idion] at all.
     From: Aristotle (Topics [c.331 BCE], 129a27)
     A reaction: This seems to cramp our style in counterfactual discussion. Can't we even mention an individual property if we believe that it will never exist. Utopian political discussion will have to cease!
8. Modes of Existence / B. Properties / 3. Types of Properties
An 'accident' is something which may possibly either belong or not belong to a thing [Aristotle]
     Full Idea: An 'accident' [sumbebekos] is something which may possibly either belong or not belong to any one and the self-same thing, such as 'sitting posture' or 'whiteness'. This is the best definition, because it tells us the essential meaning of the term itself.
     From: Aristotle (Topics [c.331 BCE], 102b07)
     A reaction: Thus a car could be red, or not red. Accidents are contingent. It does not follow that necessary properties are essential (see Idea 12262). There are accidents [sumbebekos], propria [idion] and essences [to ti en einai].
8. Modes of Existence / E. Nominalism / 6. Mereological Nominalism
A nominalist might avoid abstract objects by just appealing to mereological sums [Reck/Price]
     Full Idea: One way for a nominalist to reject appeal to all abstract objects, including sets, is to only appeal to nominalistically acceptable objects, including mereological sums.
     From: E Reck / M Price (Structures and Structuralism in Phil of Maths [2000], §4)
     A reaction: I'm suddenly thinking that this looks very interesting and might be the way to go. The issue seems to be whether mereological sums should be seen as constrained by nature, or whether they are unrestricted. See Mereology in Ontology...|Intrinsic Identity.
9. Objects / A. Existence of Objects / 5. Individuation / e. Individuation by kind
Genus gives the essence better than the differentiae do [Aristotle]
     Full Idea: In assigning the essence [ti estin], it is more appropriate to state the genus than the differentiae; for he who describes 'man' as an 'animal' indicates his essence better than he who describes him as 'pedestrian'.
     From: Aristotle (Topics [c.331 BCE], 128a24)
     A reaction: See Idea 12279. This idea is only part of the story. My reading of this is simply that assigning a genus gives more information. We learn more about him when we say he is a man than when we say he is Socrates.
9. Objects / C. Structure of Objects / 8. Parts of Objects / c. Wholes from parts
In the case of a house the parts can exist without the whole, so parts are not the whole [Aristotle]
     Full Idea: In the case of a house, where the process of compounding the parts is obvious, though the parts exist, there is no reason why the whole should not be non-existent, and so the parts are not the same as the whole.
     From: Aristotle (Topics [c.331 BCE], 150a19)
     A reaction: Compare buying a piece of furniture, and being surprised to discover, when it is delivered, that it is self-assembly. This idea is a simple refutation of the claims of classical mereology, that wholes are just some parts. Aristotle uses modal claims.
9. Objects / D. Essence of Objects / 3. Individual Essences
Everything that is has one single essence [Aristotle]
     Full Idea: Everything that is has one single essence [en esti to einai].
     From: Aristotle (Topics [c.331 BCE], 141a36)
     A reaction: Does this include vague objects, and abstract 'objects'? Sceptics might ask what grounds this claim. Does Dr Jeckyll have two essences?
9. Objects / D. Essence of Objects / 7. Essence and Necessity / b. Essence not necessities
An 'idion' belongs uniquely to a thing, but is not part of its essence [Aristotle]
     Full Idea: A property [idion] is something which does not show the essence of a thing but belongs to it alone. ...No one calls anything a property which can possibly belong to something else.
     From: Aristotle (Topics [c.331 BCE], 102a18)
     A reaction: [See Charlotte Witt 106 on this] 'Property' is clearly a bad translation for such an individual item. Witt uses 'proprium', which is a necessary but nonessential property of something. Necessity is NOT the hallmark of essence. See Idea 12266.
9. Objects / E. Objects over Time / 11. End of an Object
Destruction is dissolution of essence [Aristotle]
     Full Idea: Destruction is a dissolution of essence.
     From: Aristotle (Topics [c.331 BCE], 153b30)
     A reaction: [plucked from context!] I can't think of a better way to define destruction, in order to distinguish it from damage. A vase is destroyed when its essential function cannot be recovered.
9. Objects / E. Objects over Time / 12. Origin as Essential
If two things are the same, they must have the same source and origin [Aristotle]
     Full Idea: When things are absolutely the same, their coming-into-being and destruction are also the same and so are the agents of their production and destruction.
     From: Aristotle (Topics [c.331 BCE], 152a02)
     A reaction: Thus Queen Elizabeth II has to be the result of that particular birth, and from those particular parents, as Kripke says? The inverse may not be true. Do twins have a single origin? Things that fission and then re-fuse differently? etc
9. Objects / F. Identity among Objects / 9. Sameness
'Same' is mainly for names or definitions, but also for propria, and for accidents [Aristotle]
     Full Idea: 'The same' is employed in several senses: its principal sense is for same name or same definition; a second sense occurs when sameness is applied to a property [idiu]; a third sense is applied to an accident.
     From: Aristotle (Topics [c.331 BCE], 103a24-33)
     A reaction: [compressed] 'Property' is better translated as 'proprium' - a property unique to a particular thing, but not essential - see Idea 12262. Things are made up of essence, propria and accidents, and three ways of being 'the same' are the result.
Two identical things have the same accidents, they are the same; if the accidents differ, they're different [Aristotle]
     Full Idea: If two things are the same then any accident of one must also be an accident of the other, and, if one of them is an accident of something else, so must the other be also. For, if there is any discrepancy on these points, obviously they are not the same.
     From: Aristotle (Topics [c.331 BCE], 152a36)
     A reaction: So what is always called 'Leibniz's Law' should actually be 'Aristotle's Law'! I can't see anything missing from the Aristotle version, but then, since most people think it is pretty obvious, you would expect the great stater of the obvious to get it.
Numerical sameness and generic sameness are not the same [Aristotle]
     Full Idea: Things which are the same specifically or generically are not necessarily the same or cannot possibly be the same numerically.
     From: Aristotle (Topics [c.331 BCE], 152b32)
     A reaction: See also Idea 12266. This looks to me to be a pretty precise anticipation of Peirce's type/token distinction, but without the terminology. It is reassuring that Aristotle spotted it, as that makes it more likely to be a genuine distinction.
10. Modality / A. Necessity / 6. Logical Necessity
Reasoning is when some results follow necessarily from certain claims [Aristotle]
     Full Idea: Reasoning [sullogismos] is a discussion in which, certain things having been laid down, something other than these things necessarily results through them.
     From: Aristotle (Topics [c.331 BCE], 100a25)
     A reaction: This is cited as the standard statement of the nature of logical necessity. One might challenge either the very word 'necessary', or the exact sense of the word employed here. Is it, in fact, metaphysical, or merely analytic?
14. Science / C. Induction / 1. Induction
Induction is the progress from particulars to universals [Aristotle]
     Full Idea: Induction is the progress from particulars to universals; if the skilled pilot is the best pilot and the skilled charioteer the best charioteer, then, in general, the skilled man is the best man in any particular sphere.
     From: Aristotle (Topics [c.331 BCE], 105a15)
     A reaction: It is a bit unclear whether we are deriving universal concepts, or merely general truths. Need general truths be absolute or necessary truths? Presumably occasionally the best person is not the most skilled, as in playing a musical instrument.
14. Science / C. Induction / 3. Limits of Induction
We say 'so in cases of this kind', but how do you decide what is 'of this kind'? [Aristotle]
     Full Idea: When it is necessary to establish the universal, people use the expression 'So in all cases of this kind'; but it is one of the most difficult tasks to define which of the terms proposed are 'of this kind' and which are not.
     From: Aristotle (Topics [c.331 BCE], 157a25)
     A reaction: It is particularly hard if induction is expressed as the search for universals, since the kind presumably is the universal, so the universal must be known before the induction can apply, which really is the most frightful nuisance for truth-seekers.
23. Ethics / C. Virtue Theory / 3. Virtues / a. Virtues
Friendship is preferable to money, since its excess is preferable [Aristotle]
     Full Idea: Friendship is preferable to money; for excess of friendship is preferable to excess of money.
     From: Aristotle (Topics [c.331 BCE], 118b07)
     A reaction: Compare Idea 12276, which gives a different criterion for choosing between virtues. This idea is an interesting qualification of the doctrine of the mean.
Justice and self-control are better than courage, because they are always useful [Aristotle]
     Full Idea: Justice [dikaiosune] and self-control [sophrosune] are preferable to courage, for the first two are always useful, but courage only sometimes.
     From: Aristotle (Topics [c.331 BCE], 117a36)
     A reaction: One could challenge his criterion. What of something which is absolutely vital on occasions, against something which is very mildly useful all the time? You may survive without justice, but not without courage. Compare Idea 12277.
23. Ethics / C. Virtue Theory / 4. External Goods / d. Friendship
We value friendship just for its own sake [Aristotle]
     Full Idea: We value friendship for its own sake, even if we are not likely to get anything else from it.
     From: Aristotle (Topics [c.331 BCE], 117a03)
     A reaction: In 'Ethics' he distinguishes some friendships which don't meet this requirement. Presumably true friendships survive all vicissitudes (except betrayal), but that makes such things fairly rare.
24. Political Theory / A. Basis of a State / 1. A People / a. Human distinctiveness
Man is intrinsically a civilized animal [Aristotle]
     Full Idea: It is an essential [kath' auto] property of man to be 'by nature a civilized animal'.
     From: Aristotle (Topics [c.331 BCE], 128b17)
     A reaction: I take this, along with man being intrinsically rational, to be the foundation of Aristotelian ethics. Given that we are civilized, self-evident criteria emerge for how to be good at it. A good person is, above all, a good citizen.
26. Natural Theory / B. Natural Kinds / 2. Defining Kinds
All water is the same, because of a certain similarity [Aristotle]
     Full Idea: Any water is said to be specifically the same as any other water because it has a certain similarity to it.
     From: Aristotle (Topics [c.331 BCE], 103a20)
     A reaction: (Cf. Idea 8153) It take this to be the hallmark of a natural kind, and we should not lose sight of it in the midst of discussions about rigid designation and essential identity. Tigers are only a natural kind insofar as they are indistinguishable.
28. God / B. Proving God / 2. Proofs of Reason / b. Ontological Proof critique
'Being' and 'oneness' are predicated of everything which exists [Aristotle]
     Full Idea: 'Being' and 'oneness' are predicated of everything which exists.
     From: Aristotle (Topics [c.331 BCE], 121a18)
     A reaction: Is 'oneness' predicated of water? So existence always was a predicate, it seems, until Kant told us it wasn't. That existence is a quantifier, not a predicate, seems to be up for question again these days.
29. Religion / B. Monotheistic Religion / 4. Christianity / d. Heresy
The state should kill blasphemous heretics [Erasmus]
     Full Idea: It is necessary for the preservation of the state to kill heretics that are blasphemous and seditious.
     From: Desiderius Erasmus (works [1506]), quoted by Robert Pasnau - Metaphysical Themes 1274-1671 20.2
     A reaction: He was much more tolerant of heretics who kept quiet.