20 ideas
| 4424 | A warlike philosopher challenges problems to single combat [Nietzsche] |
| Full Idea: A warlike philosopher challenges problems to single combat. | |
| From: Friedrich Nietzsche (Ecce Homo [1889], Wise §7) | |
| A reaction: And what do pacifist philosophers do? It is a moot point whether philosophy is even possible without a streak of aggression. Otherwise you circle the problem, but don't confront it. |
| 21704 | 'Impredictative' definitions fix a class in terms of the greater class to which it belongs [Linsky,B] |
| Full Idea: The ban on 'impredicative' definitions says you can't define a class in terms of a totality to which that class must be seen as belonging. | |
| From: Bernard Linsky (Russell's Metaphysical Logic [1999], 1) | |
| A reaction: So that would be defining 'citizen' in terms of the community to which the citizen belongs? If you are asked to define 'community' and 'citizen' together, where do you start? But how else can it be done? Russell's Reducibility aimed to block this. |
| 21705 | Reducibility says any impredicative function has an appropriate predicative replacement [Linsky,B] |
| Full Idea: The Axiom of Reducibility avoids impredicativity, by asserting that for any predicate of given arguments defined by quantifying over higher-order functions or classes, there is another co-extensive but predicative function of the same type of arguments. | |
| From: Bernard Linsky (Russell's Metaphysical Logic [1999], 1) | |
| A reaction: Eventually the axiom seemed too arbitrary, and was dropped. Linsky's book explores it. |
| 21727 | Definite descriptions theory eliminates the King of France, but not the Queen of England [Linsky,B] |
| Full Idea: The theory of definite descriptions may eliminate apparent commitment to such entities as the present King of France, but certainly not to the present Queen of England. | |
| From: Bernard Linsky (Russell's Metaphysical Logic [1999], 7.3) |
| 21719 | Extensionalism means what is true of a function is true of coextensive functions [Linsky,B] |
| Full Idea: With the principle of extensionality anything true of one propositional functions will be true of every coextensive one. | |
| From: Bernard Linsky (Russell's Metaphysical Logic [1999], 6.3) |
| 21723 | The task of logicism was to define by logic the concepts 'number', 'successor' and '0' [Linsky,B] |
| Full Idea: The problem for logicism was to find definitions of the primitive notions of Peano's theory, number, successor and 0, in terms of logical notions, so that the postulates could then be derived by logic alone. | |
| From: Bernard Linsky (Russell's Metaphysical Logic [1999], 7) | |
| A reaction: Both Frege and Russell defined numbers as equivalence classes. Successor is easily defined (in various ways) in set theory. An impossible set can exemplify zero. The trouble for logicism is this all relies on sets. |
| 21721 | Higher types are needed to distinguished intensional phenomena which are coextensive [Linsky,B] |
| Full Idea: The higher types are needed for intensional phenomena, cases where the same class is picked out by distinct propositional functions. | |
| From: Bernard Linsky (Russell's Metaphysical Logic [1999], 6.4) | |
| A reaction: I take it that in this way 'x is renate' can be distinguished from 'x is cordate', a task nowadays performed by possible worlds. |
| 21703 | Types are 'ramified' when there are further differences between the type of quantifier and its range [Linsky,B] |
| Full Idea: The types is 'ramified' because there are further differences between the type of a function defined in terms of a quantifier ranging over other functions and the type of those other functions, despite the functions applying to the same simple type. | |
| From: Bernard Linsky (Russell's Metaphysical Logic [1999], 1) | |
| A reaction: Not sure I understand this, but it evidently created difficulties for dealing with actual mathematics, and Ramsey showed how you could manage without the ramifications. |
| 21714 | The ramified theory subdivides each type, according to the range of the variables [Linsky,B] |
| Full Idea: The original ramified theory of types ...furthern subdivides each of the types of the 'simple' theory according to the range of the bound variables used in the definition of each propositional function. | |
| From: Bernard Linsky (Russell's Metaphysical Logic [1999], 6) | |
| A reaction: For a non-intiate like me it certainly sounds disappointing that such a bold and neat theory because a tangle of complications. Ramsey and Russell in the 1920s seem to have dropped the ramifications. |
| 21713 | Did logicism fail, when Russell added three nonlogical axioms, to save mathematics? [Linsky,B] |
| Full Idea: It is often thought that Logicism was a failure, because after Frege's contradiction, Russell required obviously nonlogical principles, in order to develop mathematics. The axioms of Reducibility, Infinity and Choice are cited. | |
| From: Bernard Linsky (Russell's Metaphysical Logic [1999], 6) | |
| A reaction: Infinity and Choice remain as axioms of the standard ZFC system of set theory, which is why set theory is always assumed to be 'up to its neck' in ontological commitments. Linsky argues that Russell saw ontology in logic. |
| 21715 | For those who abandon logicism, standard set theory is a rival option [Linsky,B] |
| Full Idea: ZF set theory is seen as a rival to logicism as a foundational scheme. Set theory is for those who have given up the project of reducing mathematics to logic. | |
| From: Bernard Linsky (Russell's Metaphysical Logic [1999], 6.1) | |
| A reaction: Presumably there are other rivals. Set theory has lots of ontological commitments. One could start at the other end, and investigate the basic ontological commitments of arithmetic. I have no idea what those might be. |
| 21729 | Construct properties as sets of objects, or say an object must be in the set to have the property [Linsky,B] |
| Full Idea: Rather than directly constructing properties as sets of objects and proving neat facts about properties by proxy, we can assert biconditionals, such as that an object has a property if and only if it is in a certain set. | |
| From: Bernard Linsky (Russell's Metaphysical Logic [1999], 7.6) | |
| A reaction: Linsky is describing Russell's method of logical construction. I'm not clear what is gained by this move, but at least it is a variant of the usual irritating expression of properties as sets of objects. |
| 2886 | The distinction between egoistic and non-egoistic acts is absurd [Nietzsche] |
| Full Idea: There are neither egoistic nor unegoistic actions: both concepts are psychologically nonsense. | |
| From: Friedrich Nietzsche (Ecce Homo [1889], 4.5) | |
| A reaction: Not quite true, but I like this observation. The idea that you could divide everyone's actions into these two groups is certainly nonsense. But some people are more altruistic than others! |
| 4426 | A bad result distorts one's judgement about the virtue of what one has done [Nietzsche] |
| Full Idea: I should prefer to exclude the bad result, the consequences, from the question of value as a matter of principle. Faced with a bad result, one loses all too easily the right perspective for what one has done. | |
| From: Friedrich Nietzsche (Ecce Homo [1889], Clever §1) | |
| A reaction: If the perspective is easily lost, we should make more effort, not ignore consequences. The question is whether you could have foreseen or controlled the consequences. |
| 4425 | The overcoming of pity I count among the noble virtues [Nietzsche] |
| Full Idea: The overcoming of pity I count among the noble virtues. | |
| From: Friedrich Nietzsche (Ecce Homo [1889], Wise §4) | |
| A reaction: Hm. I can just about see that there might be more important things than compassion for suffering, but I can't see any human activity that makes it worthwhile to trample on pity. |
| 20132 | To become what you are you must have no self-awareness [Nietzsche] |
| Full Idea: To become what one is, one must not have the faintest notion of what one is. | |
| From: Friedrich Nietzsche (Ecce Homo [1889], II.9), quoted by Brian Leiter - Nietzsche On Morality 3 'fatalism' | |
| A reaction: [Don't understand 'II.9'] Enigmatic but striking. As I understand it, Nietzsche thought that knowing what you are is virtually impossible, though he spent a lifetime studying himself. Would you recognise someone who had become what they are? |
| 20144 | Eternal recurrence is the highest attainable affirmation [Nietzsche] |
| Full Idea: Eternal recurrence is the highest formula of affirmation that is at all attainable. | |
| From: Friedrich Nietzsche (Ecce Homo [1889], III.Z-1?), quoted by Brian Leiter - Nietzsche On Morality | |
| A reaction: Did Nietzsche have in mind an even higher formulation that was unattainable? The aim of eternal recurrence is to offer the highest possible ideal that remains rooted in the nature of ordinary life. It is a cut-down version of the Form of the Good. |
| 2889 | One repays a teacher badly if one remains only a pupil [Nietzsche] |
| Full Idea: One repays a teacher badly if one remains only a pupil. | |
| From: Friedrich Nietzsche (Ecce Homo [1889], Fore) |
| 2887 | I am not an atheist because of reasoning or evidence, but because of instinct [Nietzsche] |
| Full Idea: I have absolutely no knowledge of atheism as an outcome of reasoning, still less an event: with me it is obvious by instinct. | |
| From: Friedrich Nietzsche (Ecce Homo [1889], 3.1) |
| 7482 | Resurrection developed in Judaism as a response to martyrdoms, in about 160 BCE [Anon (Dan), by Watson] |
| Full Idea: The idea of resurrection in Judaism seems to have first developed around 160 BCE, during the time of religious martyrdom, and as a response to it (the martyrs were surely not dying forever?). It is first mentioned in the book of Daniel. | |
| From: report of Anon (Dan) (27: Book of Daniel [c.165 BCE], Ch.7) by Peter Watson - Ideas | |
| A reaction: Idea 7473 suggests that Zoroaster beat them to it by 800 years. |