136 ideas
| 2136 | Philosophers become as divine and orderly as possible, by studying divinity and order [Plato] |
| Full Idea: Because a philosopher's links are with a realm which is divine and orderly, he becomes as divine and orderly as is humanly possible. | |
| From: Plato (The Republic [c.374 BCE], 500d) | |
| A reaction: Can you be too orderly? Without order nothing of any interest (to gods or men) could ever happen. |
| 7822 | A neo-Stoic movement began in the late sixteenth century [Lipsius, by Grayling] |
| Full Idea: A neo-Stoic movement began at the end of the sixteenth century, under the inspiration of the Dutch scholar Justus Lipsius. | |
| From: report of Justus Lipsius (works [1584]) by A.C. Grayling - What is Good? Ch.5 | |
| A reaction: I would take this to be just as much a movement against Christianity as the interest in the less theistic Epicurus. They wanted the virtues of Christianity without the theological trappings. |
| 13466 | We are all post-Kantians, because he set the current agenda for philosophy [Hart,WD] |
| Full Idea: We are all post-Kantians, ...because Kant set an agenda for philosophy that we are still working through. | |
| From: William D. Hart (The Evolution of Logic [2010], 2) | |
| A reaction: Hart says that the main agenda is set by Kant's desire to defend the principle of sufficient reason against Hume's attack on causation. I would take it more generally to be the assessment of metaphysics, and of a priori knowledge. |
| 13477 | The problems are the monuments of philosophy [Hart,WD] |
| Full Idea: The real monuments of philosophy are its problems. | |
| From: William D. Hart (The Evolution of Logic [2010], 2) | |
| A reaction: Presumably he means '....rather than its solutions'. No other subject would be very happy with that sort of claim. Compare Idea 8243. A complaint against analytic philosophy is that it has achieved no consensus at all. |
| 23767 | The winds of the discussion should decide its destination [Plato] |
| Full Idea: We must let our destination be decided by the winds of the discussion. | |
| From: Plato (The Republic [c.374 BCE], 394d) | |
| A reaction: Always loved that one. Had it on the wall of my teaching room. I take it that the aim is to follow reason, rather than the powerful rhetoric of some member of the group. The spirit of philosophy is to avoid prejudgement of your enquiry. |
| 23682 | It would be absurd to be precise about the small things, but only vague about the big things [Plato] |
| Full Idea: It would be absurd to devote all our energies to securing the greatest possible precision and clarity in matters of little consequence, and not to demand the highest precision in the most important things of all. | |
| From: Plato (The Republic [c.374 BCE], 504e) | |
| A reaction: I offer this to modern analytic philosophers, who often strike me as having this priority the wrong way round. Their defence, of course, is that the important things depend on the things of little consequence - but they can lose the plot with big things. |
| 13515 | To study abstract problems, some knowledge of set theory is essential [Hart,WD] |
| Full Idea: By now, no education in abstract pursuits is adequate without some familiarity with sets. | |
| From: William D. Hart (The Evolution of Logic [2010], 10) | |
| A reaction: A heart-sinking observation for those who aspire to study metaphysics and modality. The question is, what will count as 'some' familiarity? Are only professional logicians now allowed to be proper philosophers? |
| 2151 | Dialectic is the only method of inquiry which uproots the things which it takes for granted [Plato] |
| Full Idea: Dialectic is the only field of inquiry whose quest for certainty causes it to uproot the things it takes for granted in the course of its journey. | |
| From: Plato (The Republic [c.374 BCE], 533c) |
| 2154 | The ability to take an overview is the distinguishing mark of a dialectician [Plato] |
| Full Idea: The ability to take an overview is the distinguishing mark of a dialectician. | |
| From: Plato (The Republic [c.374 BCE], 537c) |
| 4011 | For Plato, rationality is a vision of and love of a cosmic rational order [Plato, by Taylor,C] |
| Full Idea: In Plato's theory, to be rational is to have a vision of rational order, and to love this order. | |
| From: report of Plato (The Republic [c.374 BCE], 537d) by Charles Taylor - Sources of the Self §4.1 | |
| A reaction: There may be a worrying elitism in this, but it helps to pinpoint the sense in which 'all philosophers are Platonists'. |
| 2093 | You must never go against what you actually believe [Plato] |
| Full Idea: You must never go against what you actually believe. | |
| From: Plato (The Republic [c.374 BCE], 350e) |
| 2130 | People often merely practice eristic instead of dialectic, because they don't analyse the subject-matter [Plato] |
| Full Idea: People often think they are practising dialectic when they are practising eristic; this is because of their inability to conduct the enquiry by dividing the subject-matter into its various aspects. | |
| From: Plato (The Republic [c.374 BCE], 454a) |
| 13469 | Tarski showed how we could have a correspondence theory of truth, without using 'facts' [Hart,WD] |
| Full Idea: It is an ancient and honourable view that truth is correspondence to fact; Tarski showed us how to do without facts here. | |
| From: William D. Hart (The Evolution of Logic [2010], 2) | |
| A reaction: This is a very interesting spin on Tarski, who certainly seems to endorse the correspondence theory, even while apparently inventing a new 'semantic' theory of truth. It is controversial how far Tarski's theory really is a 'correspondence' theory. |
| 13504 | Truth for sentences is satisfaction of formulae; for sentences, either all sequences satisfy it (true) or none do [Hart,WD] |
| Full Idea: We explain truth for sentences in terms of satisfaction of formulae. The crux here is that for a sentence, either all sequences satisfy it or none do (with no middle ground). For formulae, some sequences may satisfy it and others not. | |
| From: William D. Hart (The Evolution of Logic [2010], 4) | |
| A reaction: This is the hardest part of Tarski's theory of truth to grasp. |
| 13503 | A first-order language has an infinity of T-sentences, which cannot add up to a definition of truth [Hart,WD] |
| Full Idea: In any first-order language, there are infinitely many T-sentences. Since definitions should be finite, the agglomeration of all the T-sentences is not a definition of truth. | |
| From: William D. Hart (The Evolution of Logic [2010], 4) | |
| A reaction: This may be a warning shot aimed at Davidson's extensive use of Tarski's formal account in his own views on meaning in natural language. |
| 13500 | Conditional Proof: infer a conditional, if the consequent can be deduced from the antecedent [Hart,WD] |
| Full Idea: A 'conditional proof' licenses inferences to a conditional from a deduction of its consequent from its antecedent. | |
| From: William D. Hart (The Evolution of Logic [2010], 4) | |
| A reaction: That is, a proof can be enshrined in an arrow. |
| 2145 | In mathematics certain things have to be accepted without further explanation [Plato] |
| Full Idea: The practitioners of maths take certain things as basic, and feel no further need to explain them. | |
| From: Plato (The Republic [c.374 BCE], 510c) |
| 13502 | ∃y... is read as 'There exists an individual, call it y, such that...', and not 'There exists a y such that...' [Hart,WD] |
| Full Idea: When a quantifier is attached to a variable, as in '∃(y)....', then it should be read as 'There exists an individual, call it y, such that....'. One should not read it as 'There exists a y such that...', which would attach predicate to quantifier. | |
| From: William D. Hart (The Evolution of Logic [2010], 4) | |
| A reaction: The point is to make clear that in classical logic the predicates attach to the objects, and not to some formal component like a quantifier. |
| 13456 | Set theory articulates the concept of order (through relations) [Hart,WD] |
| Full Idea: It is set theory, and more specifically the theory of relations, that articulates order. | |
| From: William D. Hart (The Evolution of Logic [2010]) | |
| A reaction: It would seem that we mainly need set theory in order to talk accurately about order, and about infinity. The two come together in the study of the ordinal numbers. |
| 13497 | Nowadays ZFC and NBG are the set theories; types are dead, and NF is only useful for the whole universe [Hart,WD] |
| Full Idea: The theory of types is a thing of the past. There is now nothing to choose between ZFC and NBG (Neumann-Bernays-Gödel). NF (Quine's) is a more specialized taste, but is a place to look if you want the universe. | |
| From: William D. Hart (The Evolution of Logic [2010], 3) |
| 13443 | ∈ relates across layers, while ⊆ relates within layers [Hart,WD] |
| Full Idea: ∈ relates across layers (Plato is a member of his unit set and the set of people), while ⊆ relates within layers (the singleton of Plato is a subset of the set of people). This distinction only became clear in the 19th century. | |
| From: William D. Hart (The Evolution of Logic [2010], 1) | |
| A reaction: Getting these two clear may be the most important distinction needed to understand how set theory works. |
| 13442 | Without the empty set we could not form a∩b without checking that a and b meet [Hart,WD] |
| Full Idea: Without the empty set, disjoint sets would have no intersection, and we could not form a∩b without checking that a and b meet. This is an example of the utility of the empty set. | |
| From: William D. Hart (The Evolution of Logic [2010], 1) | |
| A reaction: A novice might plausibly ask why there should be an intersection for every pair of sets, if they have nothing in common except for containing this little puff of nothingness. But then what do novices know? |
| 13493 | In the modern view, foundation is the heart of the way to do set theory [Hart,WD] |
| Full Idea: In the second half of the twentieth century there emerged the opinion that foundation is the heart of the way to do set theory. | |
| From: William D. Hart (The Evolution of Logic [2010], 3) | |
| A reaction: It is foundation which is the central axiom of the iterative conception of sets, where each level of sets is built on previous levels, and they are all 'well-founded'. |
| 13495 | Foundation Axiom: an nonempty set has a member disjoint from it [Hart,WD] |
| Full Idea: The usual statement of Foundation is that any nonempty set has a member disjoint from it. This phrasing is ordinal-free and closer to the primitives of ZFC. | |
| From: William D. Hart (The Evolution of Logic [2010], 3) |
| 13461 | We can choose from finite and evident sets, but not from infinite opaque ones [Hart,WD] |
| Full Idea: When a set is finite, we can prove it has a choice function (∀x x∈A → f(x)∈A), but we need an axiom when A is infinite and the members opaque. From infinite shoes we can pick a left one, but from socks we need the axiom of choice. | |
| From: William D. Hart (The Evolution of Logic [2010], 1) | |
| A reaction: The socks example in from Russell 1919:126. |
| 13462 | With the Axiom of Choice every set can be well-ordered [Hart,WD] |
| Full Idea: It follows from the Axiom of Choice that every set can be well-ordered. | |
| From: William D. Hart (The Evolution of Logic [2010], 1) | |
| A reaction: For 'well-ordered' see Idea 13460. Every set can be ordered with a least member. |
| 13516 | If we accept that V=L, it seems to settle all the open questions of set theory [Hart,WD] |
| Full Idea: It has been said (by Burt Dreben) that the only reason set theorists do not generally buy the view that V = L is that it would put them out of business by settling their open questions. | |
| From: William D. Hart (The Evolution of Logic [2010], 10) | |
| A reaction: Hart says V=L breaks with the interative conception of sets at level ω+1, which is countable is the constructible view, but has continuum many in the cumulative (iterative) hierarch. The constructible V=L view is anti-platonist. |
| 13441 | Naïve set theory has trouble with comprehension, the claim that every predicate has an extension [Hart,WD] |
| Full Idea: 'Comprehension' is the assumption that every predicate has an extension. Naïve set theory is the theory whose axioms are extensionality and comprehension, and comprehension is thought to be its naivety. | |
| From: William D. Hart (The Evolution of Logic [2010], 1) | |
| A reaction: This doesn't, of course, mean that there couldn't be a more modest version of comprehension. The notorious difficulty come with the discovery of self-referring predicates which can't possibly have extensions. |
| 13494 | The iterative conception may not be necessary, and may have fixed points or infinitely descending chains [Hart,WD] |
| Full Idea: That the iterative sets suffice for most of ZFC does not show they are necessary, nor is it evident that the set of operations has no fixed points (as 0 is a fixed point for square-of), and no infinitely descending chains (like negative integers). | |
| From: William D. Hart (The Evolution of Logic [2010], 3) | |
| A reaction: People don't seem to worry that they aren't 'necessary', and further measures are possible to block infinitely descending chains. |
| 13457 | A 'partial ordering' is irreflexive and transitive; the sets are ordered, but not the subsets [Hart,WD] |
| Full Idea: We say that a binary relation R 'partially orders' a field A just in case R is irreflexive (so that nothing bears R to itself) and transitive. When the set is {a,b}, its subsets {a} and {b} are incomparable in a partial ordering. | |
| From: William D. Hart (The Evolution of Logic [2010], 1) |
| 13458 | A partial ordering becomes 'total' if any two members of its field are comparable [Hart,WD] |
| Full Idea: A partial ordering is a 'total ordering' just in case any two members of its field are comparable, that is, either a is R to b, or b is R to a, or a is b. | |
| From: William D. Hart (The Evolution of Logic [2010], 1) | |
| A reaction: See Idea 13457 for 'partial ordering'. The three conditions are known as the 'trichotomy' condition. |
| 13460 | 'Well-ordering' must have a least member, so it does the natural numbers but not the integers [Hart,WD] |
| Full Idea: A total order 'well-orders' its field just in case any nonempty subset B of its field has an R-least member, that is, there is a b in B such that for any a in B different from b, b bears R to a. So less-than well-orders natural numbers, but not integers. | |
| From: William D. Hart (The Evolution of Logic [2010], 1) | |
| A reaction: The natural numbers have a starting point, but the integers are infinite in both directions. In plain English, an order is 'well-ordered' if there is a starting point. |
| 13490 | Von Neumann defines α<β as α∈β [Hart,WD] |
| Full Idea: One of the glories of Von Neumann's theory of numbers is to define α < β to mean that α ∈ β. | |
| From: William D. Hart (The Evolution of Logic [2010], 3) |
| 13481 | Maybe sets should be rethought in terms of the even more basic categories [Hart,WD] |
| Full Idea: Some have claimed that sets should be rethought in terms of still more basic things, categories. | |
| From: William D. Hart (The Evolution of Logic [2010], 2) | |
| A reaction: [He cites F.William Lawvere 1966] It appears to the the context of foundations for mathematics that he has in mind. |
| 13506 | The universal quantifier can't really mean 'all', because there is no universal set [Hart,WD] |
| Full Idea: All the main set theories deny that there is a set of which everything is a member. No interpretation has a domain with everything in it. So the universal quantifier never gets to mean everything all at once; 'all' does not mean all. | |
| From: William D. Hart (The Evolution of Logic [2010], 4) | |
| A reaction: Could you have an 'uncompleted' universal set, in the spirit of uncompleted infinities? In ordinary English we can talk about 'absolutely everything' - we just can't define a set of everything. Must we 'define' our domain? |
| 13512 | Modern model theory begins with the proof of Los's Conjecture in 1962 [Hart,WD] |
| Full Idea: The beginning of modern model theory was when Morley proved Los's Conjecture in 1962 - that a complete theory in a countable language categorical in one uncountable cardinal is categorical in all. | |
| From: William D. Hart (The Evolution of Logic [2010], 9) |
| 13505 | Model theory studies how set theory can model sets of sentences [Hart,WD] |
| Full Idea: Modern model theory investigates which set theoretic structures are models for which collections of sentences. | |
| From: William D. Hart (The Evolution of Logic [2010], 4) | |
| A reaction: So first you must choose your set theory (see Idea 13497). Then you presumably look at how to formalise sentences, and then look at the really tricky ones, many of which will involve various degrees of infinity. |
| 13511 | Model theory is mostly confined to first-order theories [Hart,WD] |
| Full Idea: There is no developed methematics of models for second-order theories, so for the most part, model theory is about models for first-order theories. | |
| From: William D. Hart (The Evolution of Logic [2010], 9) |
| 13513 | Models are ways the world might be from a first-order point of view [Hart,WD] |
| Full Idea: Models are ways the world might be from a first-order point of view. | |
| From: William D. Hart (The Evolution of Logic [2010], 9) |
| 13496 | First-order logic is 'compact': consequences of a set are consequences of a finite subset [Hart,WD] |
| Full Idea: First-order logic is 'compact', which means that any logical consequence of a set (finite or infinite) of first-order sentences is a logical consequence of a finite subset of those sentences. | |
| From: William D. Hart (The Evolution of Logic [2010], 3) |
| 13484 | Berry's Paradox: we succeed in referring to a number, with a term which says we can't do that [Hart,WD] |
| Full Idea: Berry's Paradox: by the least number principle 'the least number denoted by no description of fewer than 79 letters' exists, but we just referred to it using a description of 77 letters. | |
| From: William D. Hart (The Evolution of Logic [2010], 3) | |
| A reaction: I struggle with this. If I refer to 'an object to which no human being could possibly refer', have I just referred to something? Graham Priest likes this sort of idea. |
| 13482 | The Burali-Forti paradox is a crisis for Cantor's ordinals [Hart,WD] |
| Full Idea: The Burali-Forti Paradox was a crisis for Cantor's theory of ordinal numbers. | |
| From: William D. Hart (The Evolution of Logic [2010], 3) |
| 13507 | The machinery used to solve the Liar can be rejigged to produce a new Liar [Hart,WD] |
| Full Idea: In effect, the machinery introduced to solve the liar can always be rejigged to yield another version the liar. | |
| From: William D. Hart (The Evolution of Logic [2010], 4) | |
| A reaction: [He cites Hans Herzberger 1980-81] The machinery is Tarski's device of only talking about sentences of a language by using a 'metalanguage'. |
| 8726 | Geometry can lead the mind upwards to truth and philosophy [Plato] |
| Full Idea: Geometry can attract the mind towards truth. It can produce philosophical thought, in the sense that it can reverse the midguided downwards tendencies we currently have. | |
| From: Plato (The Republic [c.374 BCE], 527b) | |
| A reaction: Hence the Academy gate bore the inscription "Let no one enter here who is ignorant of geometry". He's not necessarily wrong. Something in early education must straighten out some of the kinks in the messy human mind. |
| 13459 | The less-than relation < well-orders, and partially orders, and totally orders the ordinal numbers [Hart,WD] |
| Full Idea: We can show (using the axiom of choice) that the less-than relation, <, well-orders the ordinals, ...and that it partially orders the ordinals, ...and that it totally orders the ordinals. | |
| From: William D. Hart (The Evolution of Logic [2010], 1) |
| 13491 | The axiom of infinity with separation gives a least limit ordinal ω [Hart,WD] |
| Full Idea: The axiom of infinity with separation yields a least limit ordinal, which is called ω. | |
| From: William D. Hart (The Evolution of Logic [2010], 3) |
| 13463 | There are at least as many infinite cardinals as transfinite ordinals (because they will map) [Hart,WD] |
| Full Idea: Since we can map the transfinite ordinals one-one into the infinite cardinals, there are at least as many infinite cardinals as transfinite ordinals. | |
| From: William D. Hart (The Evolution of Logic [2010], 1) |
| 13492 | Von Neumann's ordinals generalise into the transfinite better, because Zermelo's ω is a singleton [Hart,WD] |
| Full Idea: It is easier to generalize von Neumann's finite ordinals into the transfinite. All Zermelo's nonzero finite ordinals are singletons, but if ω were a singleton it is hard to see how if could fail to be the successor of its member and so not a limit. | |
| From: William D. Hart (The Evolution of Logic [2010], 3) |
| 13446 | 19th century arithmetization of analysis isolated the real numbers from geometry [Hart,WD] |
| Full Idea: The real numbers were not isolated from geometry until the arithmetization of analysis during the nineteenth century. | |
| From: William D. Hart (The Evolution of Logic [2010], 1) |
| 13509 | We can establish truths about infinite numbers by means of induction [Hart,WD] |
| Full Idea: Mathematical induction is a way to establish truths about the infinity of natural numbers by a finite proof. | |
| From: William D. Hart (The Evolution of Logic [2010], 5) | |
| A reaction: If there are truths about infinities, it is very tempting to infer that the infinities must therefore 'exist'. A nice, and large, question in philosophy is whether there can be truths without corresponding implications of existence. |
| 13474 | Euclid has a unique parallel, spherical geometry has none, and saddle geometry has several [Hart,WD] |
| Full Idea: There is a familiar comparison between Euclid (unique parallel) and 'spherical' geometry (no parallel) and 'saddle' geometry (several parallels). | |
| From: William D. Hart (The Evolution of Logic [2010], 2) |
| 9863 | We aim for elevated discussion of pure numbers, not attaching them to physical objects [Plato] |
| Full Idea: Our discussion of numbers leads the soul forcibly upward and compels it to discuss the numbers themselves, never permitting anyone to propose for discussion numbers attached to visible or tangible bodies. | |
| From: Plato (The Republic [c.374 BCE], 525d) | |
| A reaction: This strikes me as very important, because it shows that the platonist view of numbers places little or no importance on counting, inviting the question of whether they could be understood in complete ignorance of the process of counting. |
| 9864 | In pure numbers, all ones are equal, with no internal parts [Plato] |
| Full Idea: With those numbers that can be grasped only in thought, ..each one is equal to every other, without the least difference and containing no internal parts. | |
| From: Plato (The Republic [c.374 BCE], 526a) | |
| A reaction: [Two voices in the conversation are elided] Intriguing and tantalising. Does 13 have internal parts, in the platonist view? If so, is it more than the sum of its parts? Is Plato committed to numbers being built from indistinguishable abstract units/ |
| 8727 | Geometry is not an activity, but the study of unchanging knowledge [Plato] |
| Full Idea: Geometers talk as if they were actually doing something, and the point of their theorems is to have some effect (like 'squaring'). ...But the sole purpose is knowledge, of things which exist forever, not coming into existence and passing away. | |
| From: Plato (The Republic [c.374 BCE], 527a) | |
| A reaction: Modern Constructivism defends the view which Plato is attacking. The existence of real infinities can be doubted simply because we have not got enough time to construct them. |
| 9861 | The same thing is both one and an unlimited number at the same time [Plato] |
| Full Idea: We see the same thing to be both one and an unlimited number at the same time. | |
| From: Plato (The Republic [c.374 BCE], 525a) | |
| A reaction: Frege makes the same point, that a pair of boots is both two and one. The point is at its strongest in opposition to empirical accounts of arithmetic. However, Mill observes that pebbles can be both 5 and 3+2, without contradiction. |
| 13471 | Mathematics makes existence claims, but philosophers usually say those are never analytic [Hart,WD] |
| Full Idea: The thesis that no existence proposition is analytic is one of the few constants in philosophical consciences, but there are many existence claims in mathematics, such as the infinity of primes, five regular solids, and certain undecidable propositions. | |
| From: William D. Hart (The Evolution of Logic [2010], 2) |
| 9862 | To become rational, philosophers must rise from becoming into being [Plato] |
| Full Idea: Philosophers must rise up out of becoming and grasp being, if they are ever to become rational. | |
| From: Plato (The Republic [c.374 BCE], 525b) | |
| A reaction: I am never quite sure what 'being' means in such contexts, and it seems suffused with mysticism. In Plato's case, it is obviously related to what is unchanging, but why would something lack 'being', just because it underwent change? |
| 21818 | Being depends on the Good, which is not itself being, but superior to being [Plato] |
| Full Idea: Not only do the objects of knowledge owe their being known to the good, but their being is also due to it, although the good is not being, but superior to it in rank and power. | |
| From: Plato (The Republic [c.374 BCE], 509b) | |
| A reaction: I was surprised to find that in Plotinus the One is not being, because it is the source of being, and thus superior to being. Then a footnote sent me here, and I realise that Plato thought that the Form of the Good is superior to Being. |
| 2061 | The best things (gods, healthy bodies, good souls) are least liable to change [Plato] |
| Full Idea: The best things (such as a god, a healthy body, or a good soul) are least liable to alteration or change. | |
| From: Plato (The Republic [c.374 BCE], 380e) |
| 13488 | Mass words do not have plurals, or numerical adjectives, or use 'fewer' [Hart,WD] |
| Full Idea: Jespersen calls a noun a mass word when it has no plural, does not take numerical adjectives, and does not take 'fewer'. | |
| From: William D. Hart (The Evolution of Logic [2010], 3) | |
| A reaction: Jespersen was a great linguistics expert. |
| 6562 | Plato's reality has unchanging Parmenidean forms, and Heraclitean flux [Plato, by Fogelin] |
| Full Idea: For Plato, the intelligible world - the world of eternal and unchanging forms - is Parmenidean; the world of appearances - the world of flux we inhabit - is Heraclitean. | |
| From: report of Plato (The Republic [c.374 BCE]) by Robert Fogelin - Walking the Tightrope of Reason Ch.1 | |
| A reaction: Parmenides said reality is 'One'; Heraclitus said reality is 'flux'. This is a nice summary of Plato's view, and encapsulates two key influences on Plato, though the mathematical reality of Pythagoras should also be mentioned on the 'forms' side. |
| 2142 | The plurality of beautiful things must belong to a single class, because they have a single particular character [Plato] |
| Full Idea: All the things we refer to as pluralities (e.g. beautiful things) we also count as belonging to a single class by virtue of the fact that they have a single particular character. | |
| From: Plato (The Republic [c.374 BCE], 507b) |
| 5094 | Plato's Forms are said to have no location in space [Plato, by Aristotle] |
| Full Idea: Plato claims that the Forms are not beyond the heavens, because they are not anywhere. | |
| From: report of Plato (The Republic [c.374 BCE]) by Aristotle - Physics 203a09 | |
| A reaction: This is an important corrective to caricature accounts of Plato's Forms (encouraged, I'm afraid, by 'Phaedrus'), when critics talk about 'Platonic Heaven'. Forms are not part of space-time. I like the view that they are hypothetical truths. |
| 12043 | Forms are not universals, as they don't cover every general term [Plato, by Annas] |
| Full Idea: Despite a widely misinterpreted passage in the Republic, Plato does not think that there is a Form for every general term; Forms are not what came to be called universals. | |
| From: report of Plato (The Republic [c.374 BCE]) by Julia Annas - Ancient Philosophy: very short introduction Ch.5 | |
| A reaction: Hm. This is a bit of a blow to someone who has catalogued Platonic Forms under 'Universals'. See also Idea 12042, for what Annas thinks Plato may really have had in mind. |
| 2159 | Craftsmen making furniture refer to the form, but no one manufactures the form of furniture [Plato] |
| Full Idea: The manufacture of beds and tables involves the craftsman looking to the form and then making the furniture. The form itself is not manufactured by anyone. | |
| From: Plato (The Republic [c.374 BCE], 596b) |
| 17 | A Form applies to a set of particular things with the same name [Plato] |
| Full Idea: We always postulate a single form for each set of particular things, to which we apply the same name. | |
| From: Plato (The Republic [c.374 BCE], 596a) | |
| A reaction: This implies that the Forms have a great deal in common with the things, but also hints at the possibility of the Form being quite different from the particular things. |
| 12122 | Plato mistakenly thought forms were totally abstracted away from matter [Bacon on Plato] |
| Full Idea: Plato lost the real fruit of his opinion, by considering forms as absolutely abstracted from matter, and not confined and determined by matter. | |
| From: comment on Plato (The Republic [c.374 BCE]) by Francis Bacon - The Advancement of Learning II.VII.5 | |
| A reaction: This thought is roughly what got me interested in abstraction, on which you will find many ideas in this database. Research into Bacon's thought is hampered by that fact that the logicians have hijacked abstraction in recent philosophy. |
| 5574 | Plato's Forms not only do not come from the senses, but they are beyond possibility of sensing [Plato, by Kant] |
| Full Idea: In Plato's use of the expression 'idea' we can see that he understood by it something that not only could never be borrowed from the senses, but even goes beyond the concepts of the understanding, since nothing in experience could be congruent to it. | |
| From: report of Plato (The Republic [c.374 BCE]) by Immanuel Kant - Critique of Pure Reason B370 | |
| A reaction: This is why Kant is not a Platonist - because he thinks the limits of our world are the limits of our capacity for possible experience, and Platonic Forms exceed that limit. Personally I am with Plato. I'll never experience a quark either. |
| 2133 | Knowledge must be of the permanent unchanging nature of things [Plato] |
| Full Idea: Those who can see each thing in itself, in its permanent and unvarying nature, we'll say they have knowledge and are not merely entertaining beliefs. | |
| From: Plato (The Republic [c.374 BCE], 479e) |
| 13480 | Fregean self-evidence is an intrinsic property of basic truths, rules and definitions [Hart,WD] |
| Full Idea: The conception of Frege is that self-evidence is an intrinsic property of the basic truths, rules, and thoughts expressed by definitions. | |
| From: William D. Hart (The Evolution of Logic [2010], p.350) | |
| A reaction: The problem is always that what appears to be self-evident may turn out to be wrong. Presumably the effort of arriving at a definition ought to clarify and support the self-evident ingredient. |
| 13476 | The failure of key assumptions in geometry, mereology and set theory throw doubt on the a priori [Hart,WD] |
| Full Idea: In the case of the parallels postulate, Euclid's fifth axiom (the whole is greater than the part), and comprehension, saying was believing for a while, but what was said was false. This should make a shrewd philosopher sceptical about a priori knowledge. | |
| From: William D. Hart (The Evolution of Logic [2010], 2) | |
| A reaction: Euclid's fifth is challenged by infinite numbers, and comprehension is challenged by Russell's paradox. I can't see a defender of the a priori being greatly worried about these cases. No one ever said we would be right - in doing arithmetic, for example. |
| 2162 | If theory and practice conflict, the best part of the mind accepts theory, so the other part is of lower grade [Plato] |
| Full Idea: When appearance and measure conflict…it is the best part of the mind which accepts measurements and calculations, and the part which opposes them, therefore, must be a low-grade part of the mind. | |
| From: Plato (The Republic [c.374 BCE], 603a) |
| 2140 | True belief without knowledge is like blind people on the right road [Plato] |
| Full Idea: Don't people who have a correct belief but no knowledge strike you as exactly like blind people who happen to be taking the right road? | |
| From: Plato (The Republic [c.374 BCE], 506c) | |
| A reaction: Good. I love the style of this. Most philosophical points can be made in one concise sentence, and it is only the industry of journals and academe that forces points to be extended so much. |
| 2096 | Is the function of the mind management, authority and planning - or is it one's whole way of life? [Plato] |
| Full Idea: Does the mind have a function - say, management, authority and planning? And isn't one's way of life a function of the mind? | |
| From: Plato (The Republic [c.374 BCE], 353d) | |
| A reaction: Note that this is Plato, not some Darwinian materialist. This strikes me as the correct starting point - what does a mind appear to be for (with or without the help of Darwin)? Plato's proposals seem good (though we could cut 'authority'). |
| 6009 | Psychic conflict is clear if appetite is close to the body and reason fairly separate [Plato, by Modrak] |
| Full Idea: Plato makes psychic conflict intelligible by appeal to a conception of the soul such that the soul is closely connected to the body at the level of appetite and relatively separate from the body at the level of reason. | |
| From: report of Plato (The Republic [c.374 BCE], 339b) by Deborah K.W. Modrak - Classical theories of Mind | |
| A reaction: I'm not sure about this at the level of biology or ontology, but at the phenomenal level this is obviously right. Hunger makes consciousness feel like a physical event, but doing arithmetic doesn't seem remotely physical. |
| 6041 | There is a third element to the mind - spirit - lying between reason and appetite [Plato] |
| Full Idea: Is the third element of the mind a form of reason, so that there are only two elements to it, reason and appetite? There must be a third element, if spirit ('thumos') can be shown to be distinct - and you can see it in children when they are born. | |
| From: Plato (The Republic [c.374 BCE], 441a) | |
| A reaction: This is Plato's famous tripartite doctrine of the soul, though in other dialogues he says that there is only reason and appetite. The suspicion is that he fixed the soul having three parts, to match the three parts of his republic's social structure. |
| 2127 | The mind has parts, because we have inner conflicts [Plato] |
| Full Idea: If someone is thirsty but something is making the mind resist the pull of its thirst, isn't this bound to be a different part of the mind from the thirsty part? | |
| From: Plato (The Republic [c.374 BCE], 439b) | |
| A reaction: For Descartes there is one mind pulled by appetite and the 'natural light'. For Hume they don't seem to be 'parts' of anything. For Fodor there is an integrated team of modules. I like Fodor, and good integration is virtue. |
| 1737 | The soul seems to have an infinity of parts [Aristotle on Plato] |
| Full Idea: There seem in a way to be an infinity of parts of the soul, and not only those that some have given, distinguishing the reasoning, spirited and desiderative parts, or with others the rational and irrational. | |
| From: comment on Plato (The Republic [c.374 BCE], 439b) by Aristotle - De Anima 432a25 | |
| A reaction: This seems a nice response to Plato's proposal that the psuché has two or three parts. He could have said that the soul was a unity, and has no parts, but the proposal of infinite parts seems much closer to the modern neurological view of the mind. |
| 13475 | The Fregean concept of GREEN is a function assigning true to green things, and false to the rest [Hart,WD] |
| Full Idea: A Fregean concept is a function that assigns to each object a truth value. So instead of the colour green, the concept GREEN assigns truth to each green thing, but falsity to anything else. | |
| From: William D. Hart (The Evolution of Logic [2010], 2) | |
| A reaction: This would seem to immediately hit the renate/cordate problem, if there was a world in which all and only the green things happened to be square. How could Frege then distinguish the green from the square? Compare Idea 8245. |
| 5945 | The 'Republic' is a great work of rhetorical theory [Lawson-Tancred on Plato] |
| Full Idea: The 'Republic' is the greatest single achievement of ancient rhetorical theory. | |
| From: comment on Plato (The Republic [c.374 BCE]) by Hugh Lawson-Tancred - Plato's Republic and Greek Enlightenment Ch.9 | |
| A reaction: A lovely inversion of our normal reading of Plato! Is the real aim of philosophy the making of good speeches? Is the great aim to display the true beauty of the human mind, as the Olympics display the beauty of the body? |
| 23316 | For Plato and Aristotle there is no will; there is only rational desire for what is seen as good [Plato, by Frede,M] |
| Full Idea: Neither Plato nor Aristotle has a notion of the will. …Willing is a form of desire which is specific to reason. If reason perceives something as good, it wills or desires it. | |
| From: report of Plato (The Republic [c.374 BCE], 577e) by Michael Frede - A Free Will 1 | |
| A reaction: [Frede cites 577e, Aris. 413c8, 1113a15-, 1136b6] How do they explain the apparent decisions of non-rational animals? No modern neuroscientist thinks there is a physical object called a person's 'will'. |
| 16 | We avoid evil either through a natural aversion, or because we have acquired knowledge [Plato] |
| Full Idea: Unless a man is born with a heaven-sent aversion to wrong-doing, or acquires the knowledge to refrain from it, he will never do right of his own free will. | |
| From: Plato (The Republic [c.374 BCE], 366c) | |
| A reaction: This is the territory explored so carefully by Aristotle (after he had read Republic!). It is hard to see what the knowledge could be, other than awareness of consequences. |
| 16565 | Without the surface decoration, poetry shows only appearances and nothing of what is real [Plato] |
| Full Idea: If you strip a poet's works of their musical colorings and take them by themselves, I think you know what they look like. …We say that a maker of an image - an imitator - knows nothing about that which is but only about its appearance. | |
| From: Plato (The Republic [c.374 BCE], 601a) | |
| A reaction: Knowing the appearances well is more than most people can manage, and aspirations to know the true reality may be an idle dream. Poets are, I presume, welcome in the Cave. |
| 2160 | Representation is two steps removed from the truth [Plato] |
| Full Idea: The province of representation is indeed two steps removed from the truth. | |
| From: Plato (The Republic [c.374 BCE], 602c) |
| 2163 | Artists should be excluded from a law-abiding community, because they destroy the rational mind [Plato] |
| Full Idea: We are right to refuse admission to artists in any community which is going to respect convention, because he destroys the rational mind and feeds the irrational - it is like destroying good citizens by giving ruffians power. | |
| From: Plato (The Republic [c.374 BCE], 605b) |
| 2135 | Truth is closely related to proportion [Plato] |
| Full Idea: Truth is closely related to proportion. | |
| From: Plato (The Republic [c.374 BCE], 486d) |
| 2141 | I suggest that we forget about trying to define goodness itself for the time being [Plato] |
| Full Idea: I suggest that we forget about trying to define goodness itself for the time being. | |
| From: Plato (The Republic [c.374 BCE], 506e) | |
| A reaction: This was a source of some humour in the ancient world (in the theatre). Goodness is like some distant glow, which can never be approached in order to learn of its source. |
| 1869 | The good cannot be expressed in words, but imprints itself upon the soul [Plato, by Celsus] |
| Full Idea: Plato points to the truth about the highest good when he says that it cannot be expressed in words, but rather comes from familiarity - like a flash from the blue, imprinting itself upon the soul. | |
| From: report of Plato (The Republic [c.374 BCE]) by Celsus - On the True Doctrine (Against Christians) VII | |
| A reaction: It is reasonable to be drawn to something inexpressible, such as an appealing piece of music, but not good philosophy to build a system around something so obscure. |
| 4115 | Plato found that he could only enforce rational moral justification by creating an authoritarian society [Williams,B on Plato] |
| Full Idea: For Plato, the problem of making the ethical into a force was the problem of making society embody rational justification, and that problem could only have an authoritarian solution. | |
| From: comment on Plato (The Republic [c.374 BCE]) by Bernard Williams - Ethics and the Limits of Philosophy Ch. 2 | |
| A reaction: Plato's citizens were largely illiterate. We can be more carrot and less stick. |
| 4547 | Plato measured the degree of reality by the degree of value [Nietzsche on Plato] |
| Full Idea: Plato measured the degree of reality by the degree of value. | |
| From: comment on Plato (The Republic [c.374 BCE], 518d) by Friedrich Nietzsche - The Will to Power (notebooks) §572 | |
| A reaction: A most interesting comment. It epitomises the Nietzschean reading of Plato, in which the will to power leads the sense of value, which in turn creates the metaphysics. |
| 2094 | A thing's function is what it alone can do, or what it does better than other things [Plato] |
| Full Idea: The function of anything is what it alone can do, or what it can do better than anything else. | |
| From: Plato (The Republic [c.374 BCE], 353a) | |
| A reaction: I take this concept to be the lynchpin of Aristotle's virtue ethics. Note that it arises earlier, in Plato. Perhaps he should say what it is 'meant to do'. |
| 2095 | If something has a function then it has a state of being good [Plato] |
| Full Idea: Anything which has been endowed with a function also has a state of being good. | |
| From: Plato (The Republic [c.374 BCE], 353b) | |
| A reaction: 'ought' from 'is'? |
| 2129 | Goodness is mental health, badness is mental sickness [Plato] |
| Full Idea: Goodness is a state of mental health, bloom and vitality; badness is a state of mental sickness, deformity and infirmity. | |
| From: Plato (The Republic [c.374 BCE], 444e) | |
| A reaction: A nice statement of the closeness of goodness to health for the Greeks. The key point is that health is a deeply natural concept, which bridges the fact-value divide. |
| 12 | If we were invisible, would the just man become like the unjust? [Plato] |
| Full Idea: Glaucon: with a ring of invisibility 'the just man would differ in no way from the unjust'. | |
| From: Plato (The Republic [c.374 BCE], 360c) | |
| A reaction: I think a highly altruistic person would behave well with the ring, but I'm sure Glaucon would claim that these habits would wear off after a while. But I doubt that. |
| 2168 | Clever criminals do well at first, but not in the long run [Plato] |
| Full Idea: Clever criminals are exactly like those runners who do well on the way up the track, and then flag on the way back. | |
| From: Plato (The Republic [c.374 BCE], 613b) | |
| A reaction: Presumably there is some concept of natural justice lurking behind this comparison. Apart from the money, though, it is hard to imagine any professional criminal leading a flourishing life. |
| 2137 | The main aim is to understand goodness, which gives everything its value and advantage [Plato] |
| Full Idea: The most important thing to try to understand is the character of goodness, because this is where anything which is moral (or whatever) gets its value and advantages from. | |
| From: Plato (The Republic [c.374 BCE], 505a) | |
| A reaction: I think I'm with Aristotle on this. I understand a good lunch or a good person, but pure goodness just seems to be an empty placeholder. A vote in favour. |
| 2139 | Every person, and every activity, aims at the good [Plato] |
| Full Idea: The Good is something which everyone is after, and is the goal of all their activities. | |
| From: Plato (The Republic [c.374 BCE], 505d) | |
| A reaction: An obvious danger of tautology. If a blood crazed army is 'after' a massacre of some sort, that seems to qualify. What proportion is needed for 'everyone'? |
| 4007 | For Plato we abandon honour and pleasure once we see the Good [Plato, by Taylor,C] |
| Full Idea: For Plato, once we see the Good, we cease to be fascinated by and absorbed in the search for honour and pleasure as we were before. | |
| From: report of Plato (The Republic [c.374 BCE], 505d) by Charles Taylor - Sources of the Self §3.2 | |
| A reaction: This is the quasi-religious aspect of the Good - that it is more like a vision than a reason |
| 2144 | Goodness makes truth and knowledge possible [Plato] |
| Full Idea: It is goodness which gives the things we know their truth and makes it possible for people to have knowledge. | |
| From: Plato (The Republic [c.374 BCE], 508e) | |
| A reaction: If we take truth to be the hallmark of successful thinking, then I have no idea what this means. I can't see how truth would disappear in an amoral cosmos. |
| 2164 | Bad is always destructive, where good preserves and benefits [Plato] |
| Full Idea: Badness always manifests in destruction and corruption, while goodness always manifests in preservation and benefit. | |
| From: Plato (The Republic [c.374 BCE], 608e) | |
| A reaction: Suspicions of tautology in this one. Can we have any concepts of good or bad which are not linked to desirable or undesirable outcomes? |
| 2143 | Good has the same role in the world of knowledge as the sun has in the physical world [Plato] |
| Full Idea: As goodness stands in the intelligible realm to intelligence and the things we know, so in the visible realm the sun stands to sight and the things we see. | |
| From: Plato (The Republic [c.374 BCE], 508c) | |
| A reaction: The claim seems to be that only goodness makes the world intelligible, but that strikes as closer to mysticism than to objective observation. |
| 2147 | The sight of goodness leads to all that is fine and true and right [Plato] |
| Full Idea: The sight of goodness shows that it is responsible for everything that is right and fine,…and it is the source and provider of truth and knowledge. It is necessary for intelligent conduct of private and public affairs. | |
| From: Plato (The Republic [c.374 BCE], 517c) | |
| A reaction: As so often with Plato, I am baffled by such a claim. I sometimes see things in the world which strike me as right or fine, but I cannot conceive of a separate 'sight of goodness'. |
| 2138 | Pleasure is commonly thought to be the good, though the more ingenious prefer knowledge [Plato] |
| Full Idea: The usual view of goodness is that it is pleasure, while there's also a more ingenious view that it is knowledge. | |
| From: Plato (The Republic [c.374 BCE], 505b) | |
| A reaction: Pleasure clearly has an attraction for everyone (even puritans), and is thus a plausible natural candidate. Is this pure or instrumental knowledge? Hard to justify the former. |
| 2070 | Even people who think pleasure is the good admit that there are bad pleasures [Plato] |
| Full Idea: Those who define good as pleasure are clearly confused, and are compelled to admit that there are bad pleasures, so that the same thing is both good and bad. | |
| From: Plato (The Republic [c.374 BCE], 505c) | |
| A reaction: The issue is whether the pleasure can be disentangled from the action. 'It was a hideous murder, but at least the murderer enjoyed it'. Sounds wrong to me. |
| 2157 | Nice smells are intensive, have no preceding pain, and no bad after-effect [Plato] |
| Full Idea: Nice smells have no preceding feeling of pain, they are very intense, and they leave no distress when they are over. | |
| From: Plato (The Republic [c.374 BCE], 584b) | |
| A reaction: A nice example for extreme puritans to contemplate. Objections to enjoying nice smells seem almost inconceivable. Puritans will, I suppose, say 'slippery slope'. |
| 2134 | Philosophers are concerned with totally non-physical pleasures [Plato] |
| Full Idea: A person concerned with learning is concerned with purely mental pleasure, having nothing to do with pleasures reaching the mind through the body - assuming the person is a genuine philosopher. | |
| From: Plato (The Republic [c.374 BCE], 485d) | |
| A reaction: It is hard to find any argument which can demonstrate that mental pleasures are superior to physical ones. Mill notably failed to do it. |
| 2156 | There are three types of pleasure, for reason, for spirit and for appetite [Plato] |
| Full Idea: Each of the three mental categories (reason, spirit, appetite) has its own particular pleasure, so that there are three kinds of pleasure. | |
| From: Plato (The Republic [c.374 BCE], 580d) | |
| A reaction: I'm not sure why the types of pleasure are distinguished by mental faculties, rather than by the variety of sources of the pleasure. |
| 2158 | Pleasure-seekers desperately seek illusory satisfaction, like filling a leaky vessel [Plato] |
| Full Idea: Pleasure-seekers desperately and violently seek satisfaction in unreal things for a part of themselves which is also unreal - a leaky vessel they're trying to fill. | |
| From: Plato (The Republic [c.374 BCE], 586b) | |
| A reaction: Plato dreams of some enduring 'satisfaction' which never fades. He should have attended more to Heraclitus, and less to Parmenides. |
| 2123 | Excessive pleasure deranges people, making the other virtues impossible [Plato] |
| Full Idea: Self-discipline and excessive pleasure cannot go together, because pleasure deranges people just as much as distress. Excessive pleasure cannot partner any of the other virtues. | |
| From: Plato (The Republic [c.374 BCE], 402e) | |
| A reaction: This invites an examination of the word 'excessive', which seems too subjective. Aristotle says any good is improved by the addition of pleasure. Pleasure can certainly derange people. |
| 2166 | We should behave well even if invisible, for the health of the mind [Plato] |
| Full Idea: There's nothing better for the mind than morality, and a person ought to behave morally whether or not he owns Gyges' ring. | |
| From: Plato (The Republic [c.374 BCE], 612b) |
| 2097 | Isn't it better to have a reputation for goodness than to actually be good? [Plato] |
| Full Idea: Unless I gain a reputation for morality, my actually being moral will do me no good, but an immoral person who has managed to get a reputation for morality is said to have a wonderful life. | |
| From: Plato (The Republic [c.374 BCE], 365b) |
| 19946 | Morality is a compromise, showing restraint, to avoid suffering wrong without compensation [Plato] |
| Full Idea: The origin and nature of morality is a compromise between the ideal of doing wrong without paying for it, and the worst situation, which is having wrong done to one while lacking the means of exacting compensation. | |
| From: Plato (The Republic [c.374 BCE], 359a) | |
| A reaction: This idea is from Glaucon, and is not endorsed by Socrates. Hobbes thought it was right, though he emphasised safety. Game theory makes this approach to moraliy much more plausible. |
| 5 | Justice is merely the interests of the stronger party [Plato] |
| Full Idea: Thrasymachus: Justice or right is simply what is in the interest of the stronger party. | |
| From: Plato (The Republic [c.374 BCE], 338c) | |
| A reaction: Not sure whether this is cynicism about the brutal realities of life, or cynicism about the very concept of justice. |
| 7 | Surely you don't return a borrowed weapon to a mad friend? [Plato] |
| Full Idea: If one borrowed a weapon from a friend who subsequently went out of his mind and then asked for it back, surely one ought not to return it? | |
| From: Plato (The Republic [c.374 BCE], 331c) | |
| A reaction: Only a Kantian would think of disagreeing with this obvious truth. There is no promise here, but an implicit moral commitment. Such things should always have an all-things-being-equal clause. |
| 8 | Is right just the interests of the powerful? [Plato] |
| Full Idea: Thrasymachus: right is the interest of the established government. | |
| From: Plato (The Republic [c.374 BCE], 339a) | |
| A reaction: To believe this you would have to believe the powerful control not what is judged to be right, but also the ordinary language which expresses such judgements. Marxism explains that. |
| 15 | Sin first, then sacrifice to the gods from the proceeds [Plato] |
| Full Idea: The thing to do is to sin first and sacrifice afterwards from the proceeds. | |
| From: Plato (The Republic [c.374 BCE], 365e) | |
| A reaction: A bit like Graham Greene's Catholicism. One Greek view of the gods seems to be that they are quite myopic and naïve. |
| 5944 | For Plato, virtue is its own reward [Lawson-Tancred on Plato] |
| Full Idea: The 'Republic' is the first sustained philosophical defence of the idea that virtue is its own reward. | |
| From: comment on Plato (The Republic [c.374 BCE], Ch.9) by Hugh Lawson-Tancred - Plato's Republic and Greek Enlightenment | |
| A reaction: Sceptics might say that at the heart of his claim is the idea that the virtuous life is the best means of achieving long-term pleasure (as opposed to short-sighted hedonism). What is it about people which could make virtue attractive to them? |
| 2155 | True goodness requires mental unity and harmony [Plato] |
| Full Idea: True goodness requires mental unity and harmony. | |
| From: Plato (The Republic [c.374 BCE], 554e) |
| 2126 | A good community necessarily has wisdom, courage, self-discipline and morality [Plato] |
| Full Idea: A good community has everything which is good, so it necessarily has wisdom, courage, self-discipline and morality. | |
| From: Plato (The Republic [c.374 BCE], 427e) |
| 23562 | If the parts of our soul do their correct work, we will be just people, and will act justly [Plato] |
| Full Idea: Each one of us in whom each part is doing its own work will himself be just and do his own. …So it is appropriate for the rational part to rule …and for the spirited part to obey. | |
| From: Plato (The Republic [c.374 BCE], 441d) | |
| A reaction: 'Do his own' must mean play his own part in society correctly, because his internal faculties are also correctly focused on their role. So balancing the three parts in persons and society is not just an analogy, but one leads to the other. See 443e. |
| 2092 | Simonides said morality is helping one's friends and harming one's enemies [Plato] |
| Full Idea: Simonides claims that morality is doing good to one's friends and harm to one's enemies. | |
| From: Plato (The Republic [c.374 BCE], 332d) |
| 19889 | People need society because the individual has too many needs [Plato] |
| Full Idea: Society originates because the individual is not self-sufficient, but has many needs which he cannot supply himself. | |
| From: Plato (The Republic [c.374 BCE], 369b) | |
| A reaction: Notice that Plato has the liberal individualist approach to problem, of starting with isolated individuals, and asking why they need to gang together. This is despite the dependency of children, and the proximity of extended families. |
| 19890 | All exchanges in a community are for mutual benefit [Plato] |
| Full Idea: In the community all mutual exchanges are made on the assumption that the parties to them stand to gain. | |
| From: Plato (The Republic [c.374 BCE], 369c) | |
| A reaction: The sole purpose of his society appears to be trading, either of goods or of services. The assumption is that if each individual were self-sufficient there would be no society, which strikes me as unlikely. Aristotle offers a better picture. |
| 10 | After a taste of mutual harm, men make a legal contract to avoid it [Plato] |
| Full Idea: Once people experience committing wrong and suffering it, they see the disadvantages are unavoidable and the benefits unobtainable, ...so they enter into a contract, guaranteeing no permitting or receiving wrong, ...and they then make laws and decrees. | |
| From: Plato (The Republic [c.374 BCE], 359a) | |
| A reaction: This seems to be the earliest statement of the social contract idea. Here it both sets up the state and creates morality. This is Glaucon speaking, and is NOT endorsed by Socrates. |
| 23561 | People doing their jobs properly is the fourth cardinal virtue for a city [Plato] |
| Full Idea: The power that consists in everyone's doing his own work rivals wisdom, moderation, and courage in its contribution to the virtue of the city. | |
| From: Plato (The Republic [c.374 BCE], 433d) | |
| A reaction: Making conscientious the fourth cardinal virtue. Well said! My maxim for the modern world is that nearly all human misery consists of either bad health or other people not doing their jobs properly. You know I'm right. |
| 2149 | Reluctant rulers make a better and more unified administration [Plato] |
| Full Idea: The less keen the would-be rulers of a community are to rule, the better and less divided the administration of that community are bound to be. | |
| From: Plato (The Republic [c.374 BCE], 520d) |
| 2132 | Only rule by philosophers of integrity can keep a community healthy [Plato] |
| Full Idea: Unless communities have philosophers as kings, or the people who are currently called kings and rulers practise philosophy with enough integrity, there can be no end to political troubles. | |
| From: Plato (The Republic [c.374 BCE], 473d) |
| 2131 | Is there anything better for a community than to produce excellent people? [Plato] |
| Full Idea: Is anything better for a community than for it to engender women and men who are exceptionally good? | |
| From: Plato (The Republic [c.374 BCE], 456e) |
| 2152 | Dialectic is the highest and most important part of the curriculum [Plato] |
| Full Idea: Dialectic occupies the highest position and forms, as it were, the copestone of the curriculum. | |
| From: Plato (The Republic [c.374 BCE], 534e) |
| 2148 | To gain knowledge, turn away from the world of change, and focus on true goodness [Plato] |
| Full Idea: To gain knowledge we must turn the mind away from the world of becoming, until it becomes capable of bearing the sight of real being and reality at its most bright, which we are saying is goodness. | |
| From: Plato (The Republic [c.374 BCE], 518c) |
| 2153 | Compulsory intellectual work never remains in the mind [Plato] |
| Full Idea: Compulsory intellectual work never remains in the mind. | |
| From: Plato (The Republic [c.374 BCE], 536e) |
| 2630 | If Plato's God is immaterial, he will lack consciousness, wisdom, pleasure and movement, which are essential to him [Cicero on Plato] |
| Full Idea: Plato holds God to be without a body, immaterial; but this is an incomprehensible idea. Such a god would inevitably lack any consciousness, any wisdom and any pleasure (…or motion), all of which are bound up in our idea of God. | |
| From: comment on Plato (The Republic [c.374 BCE]) by M. Tullius Cicero - On the Nature of the Gods ('De natura deorum') I.30 |
| 14 | If the gods are non-existent or indifferent, why bother to deceive them? [Plato] |
| Full Idea: If there are no gods or if they care nothing for human affairs, why should we bother to deceive them? | |
| From: Plato (The Republic [c.374 BCE], 365d) | |
| A reaction: There is incipient deism here, as well as atheism. |
| 2165 | Something is unlikely to be immortal if it is imperfectly made from diverse parts [Plato] |
| Full Idea: Something is unlikely to be immortal if it's a compound, formed imperfectly from diverse parts. | |
| From: Plato (The Republic [c.374 BCE], 611b) |
| 13 | Is the supreme reward for virtue to be drunk for eternity? [Plato] |
| Full Idea: (the poets think) 'the supreme reward of virtue was to be drunk for eternity'. | |
| From: Plato (The Republic [c.374 BCE], 363d) | |
| A reaction: A perceptive thought. Most people consider the best life to contain endless fun and physical pleasure, so a boozy bawdy holiday in the sunshine ticks all the boxes. |
| 2120 | God is responsible for the good things, but we must look elsewhere for the cause of the bad things [Plato] |
| Full Idea: God and God alone must be held responsible for the good things, but responsibility for bad things must be looked for elsewhere, and not attributed to God. | |
| From: Plato (The Republic [c.374 BCE], 379c) |