33 ideas
| 8220 | Philosophy is in a perpetual state of digression [Deleuze/Guattari] |
| Full Idea: Philosophy can be seen as being in a perpetual state of digression. | |
| From: G Deleuze / F Guattari (What is Philosophy? [1991], 1.1) | |
| A reaction: Anyone who has ever tried to teach philosophy will vouch for this. Philosophy is the 'Arabian Nights', conjuring up wonderful stories, to avoid having to face something nasty. Philosophy is perpetual postponement of problems. |
| 8217 | Philosophy is a concept-creating discipline [Deleuze/Guattari] |
| Full Idea: Philosophy is the discipline that involves creating concepts. | |
| From: G Deleuze / F Guattari (What is Philosophy? [1991], Intro) | |
| A reaction: One might very reasonably reply that Geography is a discipline which creates concepts. However, this emphasis is an interesting corrective to the school of analysis, which appears confined to existing, and even 'folk', concepts. |
| 8242 | Philosophy aims at what is interesting, remarkable or important - not at knowledge or truth [Deleuze/Guattari] |
| Full Idea: Philosophy does not consist in knowing, and is not inspired by truth. Rather, it is categories like Interesting, Remarkable, or Important that determine success or failure. | |
| From: G Deleuze / F Guattari (What is Philosophy? [1991], 1.3) | |
| A reaction: Speak for yourself. I wonder what the criteria are for 'Interesting' or 'Important'. They can't seriously count 'remarkable' as a criterion of philosophical success, can they? There can be remarkable stupidity. |
| 8223 | The plague of philosophy is those who criticise without creating, and defend dead concepts [Deleuze/Guattari] |
| Full Idea: Those who criticise without creating, those who are content to defend the vanished concept without being able to give it the forces it needs to return to life, are the plague of philosophy. | |
| From: G Deleuze / F Guattari (What is Philosophy? [1991], 1.1) | |
| A reaction: This seems to be the continental view of analytical philosophy, that it is pathetically conservative. I would offer MacIntyre as a response, who gives a beautiful analysis of why the super-modern view is dead. The French are hopelessly romantic. |
| 8247 | Phenomenology needs art as logic needs science [Deleuze/Guattari] |
| Full Idea: Phenomenology needs art as logic needs science. | |
| From: G Deleuze / F Guattari (What is Philosophy? [1991], 2.6) | |
| A reaction: I would have thought that it was science that needs logic. Art is more elitist than science, and less universal. I presume artists and phenomenologists share a target of deconstructing lived human experience. |
| 8224 | 'Eris' is the divinity of conflict, the opposite of Philia, the god of friendship [Deleuze/Guattari] |
| Full Idea: 'Eris' is the Greek divinity of discord, conflict, and strife, the complementary opposite of Philia, the divinity of union and friendship. | |
| From: G Deleuze / F Guattari (What is Philosophy? [1991], 1.2 n) | |
| A reaction: Are these actual gods? This interestingly implies that the wonders of dialectic and Socrates' elenchus are simply aspects of friendship, which was elevated by Epicurus to the highest good. The Greeks just wanted wonderful friends and fine speeches. |
| 13838 | A decent modern definition should always imply a semantics [Hacking] |
| Full Idea: Today we expect that anything worth calling a definition should imply a semantics. | |
| From: Ian Hacking (What is Logic? [1979], §10) | |
| A reaction: He compares this with Gentzen 1935, who was attempting purely syntactic definitions of the logical connectives. |
| 13833 | 'Thinning' ('dilution') is the key difference between deduction (which allows it) and induction [Hacking] |
| Full Idea: 'Dilution' (or 'Thinning') provides an essential contrast between deductive and inductive reasoning; for the introduction of new premises may spoil an inductive inference. | |
| From: Ian Hacking (What is Logic? [1979], §06.2) | |
| A reaction: That is, inductive logic (if there is such a thing) is clearly non-monotonic, whereas classical inductive logic is monotonic. |
| 13834 | Gentzen's Cut Rule (or transitivity of deduction) is 'If A |- B and B |- C, then A |- C' [Hacking] |
| Full Idea: If A |- B and B |- C, then A |- C. This generalises to: If Γ|-A,Θ and Γ,A |- Θ, then Γ |- Θ. Gentzen called this 'cut'. It is the transitivity of a deduction. | |
| From: Ian Hacking (What is Logic? [1979], §06.3) | |
| A reaction: I read the generalisation as 'If A can be either a premise or a conclusion, you can bypass it'. The first version is just transitivity (which by-passes the middle step). |
| 13835 | Only Cut reduces complexity, so logic is constructive without it, and it can be dispensed with [Hacking] |
| Full Idea: Only the cut rule can have a conclusion that is less complex than its premises. Hence when cut is not used, a derivation is quite literally constructive, building up from components. Any theorem obtained by cut can be obtained without it. | |
| From: Ian Hacking (What is Logic? [1979], §08) |
| 8219 | Logic has an infantile idea of philosophy [Deleuze/Guattari] |
| Full Idea: Logic has an infantile idea of philosophy. | |
| From: G Deleuze / F Guattari (What is Philosophy? [1991], 1.1) | |
| A reaction: This offers some explanation of why Anglo-American philosophers are steeped in logic, and the continentals just ignore it. I have some sympathy with the French view. Logic seems to study language with all the interesting part drained off. |
| 8246 | Logic hates philosophy, and wishes to supplant it [Deleuze/Guattari] |
| Full Idea: A real hatred inspires logic's rivalry with, or its will to supplant, philosophy. | |
| From: G Deleuze / F Guattari (What is Philosophy? [1991], 2.6) | |
| A reaction: A delightful corrective to the neurotic inferiority that most English-speaking philosophers feel about their failure to master logic. What was Aristotle playing at when he invented logic? Philosophical talent is utterly different from a talent for logic. |
| 13845 | The various logics are abstractions made from terms like 'if...then' in English [Hacking] |
| Full Idea: I don't believe English is by nature classical or intuitionistic etc. These are abstractions made by logicians. Logicians attend to numerous different objects that might be served by 'If...then', like material conditional, strict or relevant implication. | |
| From: Ian Hacking (What is Logic? [1979], §15) | |
| A reaction: The idea that they are 'abstractions' is close to my heart. Abstractions from what? Surely 'if...then' has a standard character when employed in normal conversation? |
| 13840 | First-order logic is the strongest complete compact theory with Löwenheim-Skolem [Hacking] |
| Full Idea: First-order logic is the strongest complete compact theory with a Löwenheim-Skolem theorem. | |
| From: Ian Hacking (What is Logic? [1979], §13) |
| 13844 | A limitation of first-order logic is that it cannot handle branching quantifiers [Hacking] |
| Full Idea: Henkin proved that there is no first-order treatment of branching quantifiers, which do not seem to involve any idea that is fundamentally different from ordinary quantification. | |
| From: Ian Hacking (What is Logic? [1979], §13) | |
| A reaction: See Hacking for an example of branching quantifiers. Hacking is impressed by this as a real limitation of the first-order logic which he generally favours. |
| 13842 | Second-order completeness seems to need intensional entities and possible worlds [Hacking] |
| Full Idea: Second-order logic has no chance of a completeness theorem unless one ventures into intensional entities and possible worlds. | |
| From: Ian Hacking (What is Logic? [1979], §13) |
| 13837 | With a pure notion of truth and consequence, the meanings of connectives are fixed syntactically [Hacking] |
| Full Idea: My doctrine is that the peculiarity of the logical constants resides precisely in that given a certain pure notion of truth and consequence, all the desirable semantic properties of the constants are determined by their syntactic properties. | |
| From: Ian Hacking (What is Logic? [1979], §09) | |
| A reaction: He opposes this to Peacocke 1976, who claims that the logical connectives are essentially semantic in character, concerned with the preservation of truth. |
| 13839 | Perhaps variables could be dispensed with, by arrows joining places in the scope of quantifiers [Hacking] |
| Full Idea: For some purposes the variables of first-order logic can be regarded as prepositions and place-holders that could in principle be dispensed with, say by a system of arrows indicating what places fall in the scope of which quantifier. | |
| From: Ian Hacking (What is Logic? [1979], §11) | |
| A reaction: I tend to think of variables as either pronouns, or as definite descriptions, or as temporary names, but not as prepositions. Must address this new idea... |
| 13843 | If it is a logic, the Löwenheim-Skolem theorem holds for it [Hacking] |
| Full Idea: A Löwenheim-Skolem theorem holds for anything which, on my delineation, is a logic. | |
| From: Ian Hacking (What is Logic? [1979], §13) | |
| A reaction: I take this to be an unusually conservative view. Shapiro is the chap who can give you an alternative view of these things, or Boolos. |
| 15086 | Absolute necessity might be achievable either logically or metaphysically [Hale] |
| Full Idea: Maybe peaceful co-existence between absolute logical necessity and absolute metaphysical necessity can be secured, ..and absolute necessity is their union. ...However, a truth would then qualify as absolutely necessary in two quite different ways. | |
| From: Bob Hale (Absolute Necessities [1996], 4) | |
| A reaction: Hale is addressing a really big question for metaphysic (absolute necessity) which others avoid. In the end he votes for rejecting 'metaphysical' necessity. I am tempted to vote for rejecting logical necessity (as being relative). 'Absolute' is an ideal. |
| 8261 | Maybe not-p is logically possible, but p is metaphysically necessary, so the latter is not absolute [Hale] |
| Full Idea: It might be metaphysically necessary that p but logically possible that not-p, so that metaphysical necessity is not, after all, absolute. | |
| From: Bob Hale (Absolute Necessities [1996]), quoted by E.J. Lowe - The Possibility of Metaphysics 1.5 | |
| A reaction: Lowe presents this as dilemma, but it sounds fine to me. Flying pigs etc. have no apparent logical problems, but I can't conceive of a possible world where pigs like ours fly in a world like ours. Earthbound pigs may be metaphysically necessary. |
| 15081 | A strong necessity entails a weaker one, but not conversely; possibilities go the other way [Hale] |
| Full Idea: One type of necessity may be said to be 'stronger' than another when the first always entails the second, but not conversely. This will obtain only if the possibility of the first is weaker than the possibility of the second. | |
| From: Bob Hale (Absolute Necessities [1996], 1) | |
| A reaction: Thus we would normally say that if something is logically necessary (a very strong claim) then it will have to be naturally necessary. If something is naturally possible, then clearly it will have to be logically possible. Sounds OK. |
| 15080 | 'Relative' necessity is just a logical consequence of some statements ('strong' if they are all true) [Hale] |
| Full Idea: Necessity is 'relative' if a claim of φ-necessary that p just claims that it is a logical consequence of some statements Φ that p. We have a 'strong' version if we add that the statements in Φ are all true, and a 'weak' version if not. | |
| From: Bob Hale (Absolute Necessities [1996], 1) | |
| A reaction: I'm not sure about 'logical' consequence here. It may be necessary that a thing be a certain way in order to qualify for some category (which would be 'relative'), but that seems like 'sortal' necessity rather than logical. |
| 15082 | Metaphysical necessity says there is no possibility of falsehood [Hale] |
| Full Idea: Friends of metaphysical necessity would want to hold that when it is metaphysically necessary that p, there is no good sense of 'possible' (except, perhaps, an epistemic one) in which it is possible that not-p. | |
| From: Bob Hale (Absolute Necessities [1996], 2) | |
| A reaction: We might want to say which possible worlds this refers to (and presumably it won't just be in the actual world). The normal claim would refer to all possible worlds. Adding a '...provided that' clause moves it from absolute to relative necessity. |
| 15085 | 'Broadly' logical necessities are derived (in a structure) entirely from the concepts [Hale] |
| Full Idea: 'Broadly' logical necessities are propositions whose truth derives entirely from the concepts involved in them (together, of course, with relevant structure). | |
| From: Bob Hale (Absolute Necessities [1996], 3) | |
| A reaction: Is the 'logical' part of this necessity bestowed by the concepts, or by the 'structure' (which I take to be a logical structure)? |
| 15088 | Logical necessities are true in virtue of the nature of all logical concepts [Hale] |
| Full Idea: The logical necessities can be taken to be the propositions which are true in virtue of the nature of all logical concepts. | |
| From: Bob Hale (Absolute Necessities [1996], p.10) | |
| A reaction: This is part of his story of essences giving rise to necessities. His proposal sounds narrow, but logical concepts may have the highest degree of generality which it is possible to have. It must be how the concepts connect that causes the necessities. |
| 15087 | Conceptual necessities are made true by all concepts [Hale] |
| Full Idea: Conceptual necessities can be taken to be propositions which are true in virtue of the nature of all concepts. | |
| From: Bob Hale (Absolute Necessities [1996], p.9) | |
| A reaction: Fine endorse essences for these concepts. Could we then come up with a new concept which contradicted all the others, and destroyed the necessity? Yes, presumably. Presumably witchcraft and astrology are full of 'conceptual necessities'. |
| 8221 | We cannot judge the Cogito. Must we begin? Must we start from certainty? Can 'I' relate to thought? [Deleuze/Guattari] |
| Full Idea: There is no point in wondering whether Descartes' Cogito is right or wrong. Is it necessary "to begin", and, if so, is it necessary to start from the point of view of a subjective certainty? Can thought be the verb of an I? There is no direct answer. | |
| From: G Deleuze / F Guattari (What is Philosophy? [1991], 1.1) | |
| A reaction: A nice first sentence for a work of philosophy would be "It is necessary to begin". Is the Cogito the only idea that is beyond judgement? I fear a slippery slope here, which would paralyse all of our judgements - and would therefore be ridiculous. |
| 8222 | Concepts are superior because they make us more aware, and change our thinking [Deleuze/Guattari] |
| Full Idea: If one concept is 'better' than an earlier one, it is because it makes us aware of new variations and unknown resonances, it carries out unforeseen cuttings-out, it brings forth an Event that surveys (survole) us. | |
| From: G Deleuze / F Guattari (What is Philosophy? [1991], 1.1) | |
| A reaction: I don't get much of that, but it is certainly in tune with the Kuhn/Feyerabend idea that what science can generate is fresh visions, rather than precisely expanded truths. Personally I consider it dangerous nonsense, but I thought I ought to pass it on. |
| 8218 | Other people completely revise our perceptions, because they are possible worlds [Deleuze/Guattari] |
| Full Idea: The concept of the Other Person as expression of a possible world in a perceptual field leads us to consider the components of this field in a new way. | |
| From: G Deleuze / F Guattari (What is Philosophy? [1991], 1.1) | |
| A reaction: I like the idea that other people are possible worlds. You can give reductionist accounts of the human animal till the cows come home, but when one walk into your visual field, the mind takes off. See Crusoe and Friday. |
| 8248 | Phenomenology says thought is part of the world [Deleuze/Guattari] |
| Full Idea: According to phenomenology, thought depends on man's relations with the world - with which the brain is necessarily in agreement because it is drawn from these relations. | |
| From: G Deleuze / F Guattari (What is Philosophy? [1991], Conclusion) | |
| A reaction: The development of externalist views of mind, arising from the Twin Earth idea, seems to provide a link to continental philosophy, where similar ideas are found in Husserl, Sartre and Merleau-Ponty. So study science, psychology, or sociology? |
| 8245 | The logical attitude tries to turn concepts into functions, when they are really forms or forces [Deleuze/Guattari] |
| Full Idea: Logic is reductionist not accidentally, but essentially and necessarily: following the route marked out by Frege and Russell, it wants to turn the concept into a function (...when actually a concept is a form, or a force). | |
| From: G Deleuze / F Guattari (What is Philosophy? [1991], 2.6) | |
| A reaction: [Last part on p.144] I'm not sure that I understand 'form or force', but the idea that concepts are mere functions is like describing something as 'transport', without saying whether it is bus/bike/train.. Is a concept a vision, or a tool? |
| 8243 | Atheism is the philosopher's serenity, and philosophy's achievement [Deleuze/Guattari] |
| Full Idea: It is amazing that so many philosophers take the death of God as tragic. Atheism is not a drama, but the philosopher's serenity and philosophy's achievement. | |
| From: G Deleuze / F Guattari (What is Philosophy? [1991], 1.4) | |
| A reaction: It seems to me that it is the late nineteenth and early twentieth century that feels the death of God as a tragedy. Modern Anglo-American philosophers are mostly pretty serene on the subject, unless, like Dennett, they go on the offensive. |