49 ideas
| 21959 | Metaphysics is the most general attempt to make sense of things [Moore,AW] |
| Full Idea: Metaphysics is the most general attempt to make sense of things. | |
| From: A.W. Moore (The Evolution of Modern Metaphysics [2012], Intro) | |
| A reaction: This is the first sentence of Moore's book, and a touchstone idea all the way through. It stands up well, because it says enough without committing to too much. I have to agree with it. It implies explanation as the key. I like generality too. |
| 18405 | A 'teepee' argument has several mutually supporting planks to it [Cappelen/Dever] |
| Full Idea: In a 'teepee' argument, a number of argumentative planks intersupport each other. No plank is sufficiently strong to establish the position, but each lends credibility to the others because there is the appearance of a unified phenomenon. | |
| From: Cappelen,H/Dever,Josh (The Inessential Indexical [2013], 01.5) | |
| A reaction: To attack it, they say, you have to identify the separate planks of the argument. It is a moot point whether the teepee might be so imprecise that it is better described as 'coherence'. There is a background support, as well as the planks. |
| 15413 | With four tense operators, all complex tenses reduce to fourteen basic cases [Burgess] |
| Full Idea: Fand P as 'will' and 'was', G as 'always going to be', H as 'always has been', all tenses reduce to 14 cases: the past series, each implying the next, FH,H,PH,HP,P,GP, and the future series PG,G,FG,GF,F,HF, plus GH=HG implying all, FP=PF which all imply. | |
| From: John P. Burgess (Philosophical Logic [2009], 2.8) | |
| A reaction: I have tried to translate the fourteen into English, but am not quite confident enough to publish them here. I leave it as an exercise for the reader. |
| 15415 | The temporal Barcan formulas fix what exists, which seems absurd [Burgess] |
| Full Idea: In temporal logic, if the converse Barcan formula holds then nothing goes out of existence, and the direct Barcan formula holds if nothing ever comes into existence. These results highlight the intuitive absurdity of the Barcan formulas. | |
| From: John P. Burgess (Philosophical Logic [2009], 2.9) | |
| A reaction: This is my reaction to the modal cases as well - the absurdity of thinking that no actually nonexistent thing might possibly have existed, or that the actual existents might not have existed. Williamson seems to be the biggest friend of the formulas. |
| 15430 | Is classical logic a part of intuitionist logic, or vice versa? [Burgess] |
| Full Idea: From one point of view intuitionistic logic is a part of classical logic, missing one axiom, from another classical logic is a part of intuitionistic logic, missing two connectives, intuitionistic v and → | |
| From: John P. Burgess (Philosophical Logic [2009], 6.4) |
| 15431 | It is still unsettled whether standard intuitionist logic is complete [Burgess] |
| Full Idea: The question of the completeness of the full intuitionistic logic for its intended interpretation is not yet fully resolved. | |
| From: John P. Burgess (Philosophical Logic [2009], 6.9) |
| 15429 | Relevance logic's → is perhaps expressible by 'if A, then B, for that reason' [Burgess] |
| Full Idea: The relevantist logician's → is perhaps expressible by 'if A, then B, for that reason'. | |
| From: John P. Burgess (Philosophical Logic [2009], 5.8) |
| 15404 | Technical people see logic as any formal system that can be studied, not a study of argument validity [Burgess] |
| Full Idea: Among the more technically oriented a 'logic' no longer means a theory about which forms of argument are valid, but rather means any formalism, regardless of its applications, that resembles original logic enough to be studied by similar methods. | |
| From: John P. Burgess (Philosophical Logic [2009], Pref) | |
| A reaction: There doesn't seem to be any great intellectual obligation to be 'technical'. As far as pure logic is concerned, I am very drawn to the computer approach, since I take that to be the original dream of Aristotle and Leibniz - impersonal precision. |
| 15405 | Classical logic neglects the non-mathematical, such as temporality or modality [Burgess] |
| Full Idea: There are topics of great philosophical interest that classical logic neglects because they are not important to mathematics. …These include distinctions of past, present and future, or of necessary, actual and possible. | |
| From: John P. Burgess (Philosophical Logic [2009], 1.1) |
| 15427 | The Cut Rule expresses the classical idea that entailment is transitive [Burgess] |
| Full Idea: The Cut rule (from A|-B and B|-C, infer A|-C) directly expresses the classical doctrine that entailment is transitive. | |
| From: John P. Burgess (Philosophical Logic [2009], 5.3) |
| 15421 | Classical logic neglects counterfactuals, temporality and modality, because maths doesn't use them [Burgess] |
| Full Idea: Classical logic neglects counterfactual conditionals for the same reason it neglects temporal and modal distinctions, namely, that they play no serious role in mathematics. | |
| From: John P. Burgess (Philosophical Logic [2009], 4.1) | |
| A reaction: Science obviously needs counterfactuals, and metaphysics needs modality. Maybe so-called 'classical' logic will be renamed 'basic mathematical logic'. Philosophy will become a lot clearer when that happens. |
| 15403 | Philosophical logic is a branch of logic, and is now centred in computer science [Burgess] |
| Full Idea: Philosophical logic is a branch of logic, a technical subject. …Its centre of gravity today lies in theoretical computer science. | |
| From: John P. Burgess (Philosophical Logic [2009], Pref) | |
| A reaction: He firmly distinguishes it from 'philosophy of logic', but doesn't spell it out. I take it that philosophical logic concerns metaprinciples which compare logical systems, and suggest new lines of research. Philosophy of logic seems more like metaphysics. |
| 15407 | Formalising arguments favours lots of connectives; proving things favours having very few [Burgess] |
| Full Idea: When formalising arguments it is convenient to have as many connectives as possible available.; but when proving results about formulas it is convenient to have as few as possible. | |
| From: John P. Burgess (Philosophical Logic [2009], 1.4) | |
| A reaction: Illuminating. The fact that you can whittle classical logic down to two (or even fewer!) connectives warms the heart of technicians, but makes connection to real life much more difficult. Hence a bunch of extras get added. |
| 15424 | Asserting a disjunction from one disjunct seems odd, but can be sensible, and needed in maths [Burgess] |
| Full Idea: Gricean implicature theory might suggest that a disjunction is never assertable when a disjunct is (though actually the disjunction might be 'pertinent') - but the procedure is indispensable in mathematical practice. | |
| From: John P. Burgess (Philosophical Logic [2009], 5.2) | |
| A reaction: He gives an example of a proof in maths which needs it, and an unusual conversational occasion where it makes sense. |
| 15409 | All occurrences of variables in atomic formulas are free [Burgess] |
| Full Idea: All occurrences of variables in atomic formulas are free. | |
| From: John P. Burgess (Philosophical Logic [2009], 1.7) |
| 15414 | The denotation of a definite description is flexible, rather than rigid [Burgess] |
| Full Idea: By contrast to rigidly designating proper names, …the denotation of definite descriptions is (in general) not rigid but flexible. | |
| From: John P. Burgess (Philosophical Logic [2009], 2.9) | |
| A reaction: This modern way of putting it greatly clarifies why Russell was interested in the type of reference involved in definite descriptions. Obviously some descriptions (such as 'the only person who could ever have…') might be rigid. |
| 15406 | 'Induction' and 'recursion' on complexity prove by connecting a formula to its atomic components [Burgess] |
| Full Idea: There are atomic formulas, and formulas built from the connectives, and that is all. We show that all formulas have some property, first for the atomics, then the others. This proof is 'induction on complexity'; we also use 'recursion on complexity'. | |
| From: John P. Burgess (Philosophical Logic [2009], 1.4) | |
| A reaction: That is: 'induction on complexity' builds a proof from atomics, via connectives; 'recursion on complexity' breaks down to the atomics, also via the connectives. You prove something by showing it is rooted in simple truths. |
| 15425 | The sequent calculus makes it possible to have proof without transitivity of entailment [Burgess] |
| Full Idea: It might be wondered how one could have any kind of proof procedure at all if transitivity of entailment is disallowed, but the sequent calculus can get around the difficulty. | |
| From: John P. Burgess (Philosophical Logic [2009], 5.3) | |
| A reaction: He gives examples where transitivity of entailment (so that you can build endless chains of deductions) might fail. This is the point of the 'cut free' version of sequent calculus, since the cut rule allows transitivity. |
| 15426 | We can build one expanding sequence, instead of a chain of deductions [Burgess] |
| Full Idea: Instead of demonstrations which are either axioms, or follow from axioms by rules, we can have one ever-growing sequence of formulas of the form 'Axioms |- ______', where the blank is filled by Axioms, then Lemmas, then Theorems, then Corollaries. | |
| From: John P. Burgess (Philosophical Logic [2009], 5.3) |
| 15408 | 'Tautologies' are valid formulas of classical sentential logic - or substitution instances in other logics [Burgess] |
| Full Idea: The valid formulas of classical sentential logic are called 'tautologically valid', or simply 'tautologies'; with other logics 'tautologies' are formulas that are substitution instances of valid formulas of classical sentential logic. | |
| From: John P. Burgess (Philosophical Logic [2009], 1.5) |
| 15418 | Validity (for truth) and demonstrability (for proof) have correlates in satisfiability and consistency [Burgess] |
| Full Idea: Validity (truth by virtue of logical form alone) and demonstrability (provability by virtue of logical form alone) have correlative notions of logical possibility, 'satisfiability' and 'consistency', which come apart in some logics. | |
| From: John P. Burgess (Philosophical Logic [2009], 3.3) |
| 15412 | Models leave out meaning, and just focus on truth values [Burgess] |
| Full Idea: Models generally deliberately leave out meaning, retaining only what is important for the determination of truth values. | |
| From: John P. Burgess (Philosophical Logic [2009], 2.2) | |
| A reaction: This is the key point to hang on to, if you are to avoid confusing mathematical models with models of things in the real world. |
| 15411 | We only need to study mathematical models, since all other models are isomorphic to these [Burgess] |
| Full Idea: In practice there is no need to consider any but mathematical models, models whose universes consist of mathematical objects, since every model is isomorphic to one of these. | |
| From: John P. Burgess (Philosophical Logic [2009], 1.8) | |
| A reaction: The crucial link is the technique of Gödel Numbering, which can translate any verbal formula into numerical form. He adds that, because of the Löwenheim-Skolem theorem only subsets of the natural numbers need be considered. |
| 15416 | We aim to get the technical notion of truth in all models matching intuitive truth in all instances [Burgess] |
| Full Idea: The aim in setting up a model theory is that the technical notion of truth in all models should agree with the intuitive notion of truth in all instances. A model is supposed to represent everything about an instance that matters for its truth. | |
| From: John P. Burgess (Philosophical Logic [2009], 3.2) |
| 15428 | The Liar seems like a truth-value 'gap', but dialethists see it as a 'glut' [Burgess] |
| Full Idea: It is a common view that the liar sentence ('This very sentence is not true') is an instance of a truth-value gap (neither true nor false), but some dialethists cite it as an example of a truth-value glut (both true and false). | |
| From: John P. Burgess (Philosophical Logic [2009], 5.7) | |
| A reaction: The defence of the glut view must be that it is true, then it is false, then it is true... Could it manage both at once? |
| 15420 | De re modality seems to apply to objects a concept intended for sentences [Burgess] |
| Full Idea: There is a problem over 'de re' modality (as contrasted with 'de dicto'), as in ∃x□x. What is meant by '"it is analytic that Px" is satisfied by a', given that analyticity is a notion that in the first instance applies to complete sentences? | |
| From: John P. Burgess (Philosophical Logic [2009], 3.9) | |
| A reaction: This is Burgess's summary of one of Quine's original objections. The issue may be a distinction between whether the sentence is analytic, and what makes it analytic. The necessity of bachelors being unmarried makes that sentence analytic. |
| 15419 | General consensus is S5 for logical modality of validity, and S4 for proof [Burgess] |
| Full Idea: To the extent that there is any conventional wisdom about the question, it is that S5 is correct for alethic logical modality, and S4 correct for apodictic logical modality. | |
| From: John P. Burgess (Philosophical Logic [2009], 3.8) | |
| A reaction: In classical logic these coincide, so presumably one should use the minimum system to do the job, which is S4 (?). |
| 15417 | Logical necessity has two sides - validity and demonstrability - which coincide in classical logic [Burgess] |
| Full Idea: Logical necessity is a genus with two species. For classical logic the truth-related notion of validity and the proof-related notion of demonstrability, coincide - but they are distinct concept. In some logics they come apart, in intension and extension. | |
| From: John P. Burgess (Philosophical Logic [2009], 3.3) | |
| A reaction: They coincide in classical logic because it is sound and complete. This strikes me as the correct approach to logical necessity, tying it to the actual nature of logic, rather than some handwavy notion of just 'true in all possible worlds'. |
| 15422 | Three conditionals theories: Materialism (material conditional), Idealism (true=assertable), Nihilism (no truth) [Burgess] |
| Full Idea: Three main theories of the truth of indicative conditionals are Materialism (the conditions are the same as for the material conditional), Idealism (identifying assertability with truth-value), and Nihilism (no truth, just assertability). | |
| From: John P. Burgess (Philosophical Logic [2009], 4.3) |
| 15423 | It is doubtful whether the negation of a conditional has any clear meaning [Burgess] |
| Full Idea: It is contentious whether conditionals have negations, and whether 'it is not the case that if A,B' has any clear meaning. | |
| From: John P. Burgess (Philosophical Logic [2009], 4.9) | |
| A reaction: This seems to be connected to Lewis's proof that a probability conditional cannot be reduced to a single proposition. If a conditional only applies to A-worlds, it is not surprising that its meaning gets lost when it leaves that world. |
| 21958 | Appearances are nothing beyond representations, which is transcendental ideality [Moore,AW] |
| Full Idea: Appearances in general are nothing outside our representations, which is just what we mean by transcendental ideality. | |
| From: A.W. Moore (The Evolution of Modern Metaphysics [2012], B535/A507) |
| 18422 | Prioprioception focuses on your body parts, not on your self, or indexicality [Cappelen/Dever] |
| Full Idea: Proprioception is not focused single-mindedly on the self, but is focused on a number of objects - the component bodily parts that belong to the self. There is no obvious need for a concept of the self, or of indexicality. | |
| From: Cappelen,H/Dever,Josh (The Inessential Indexical [2013], 07.2) |
| 18425 | We can acquire self-knowledge with mirrors, not just with proprioception and introspection [Cappelen/Dever] |
| Full Idea: Imagine a being that learns everything about itself by watching itself in mirrors, rather than by proprioception and introspection. Surely it can get wet in a storm, even though allegedly distinctive routes of self-knowledge are not available to it? | |
| From: Cappelen,H/Dever,Josh (The Inessential Indexical [2013], 09.3) | |
| A reaction: [compressed] |
| 18421 | Proprioception is only immune from error if you are certain that it represents the agent [Cappelen/Dever] |
| Full Idea: The guarantee of immunity from error in prioprioception is only as strong as the guarantee that proprioception only ever represents the proprioceiving agent. | |
| From: Cappelen,H/Dever,Josh (The Inessential Indexical [2013], 07.1) | |
| A reaction: This is part of an interesting and sustained attack on the idea that self-knowledge is immune from error. They are thinking of science-fictiony situations where I am wired up to experience your leg movement. My experiences usually track me, that's all. |
| 18419 | Folk Functionalism is a Ramsification of our folk psychology [Cappelen/Dever] |
| Full Idea: According to Folk Functionalism, mental states are theoretically defined by Ramsifying on our folk-psychological theory. | |
| From: Cappelen,H/Dever,Josh (The Inessential Indexical [2013], 06.2) |
| 18404 | It is assumed that indexical content is needed to represent the perspective of perception [Cappelen/Dever] |
| Full Idea: Because our perceptual states typically represent the world as seen from a perspective, it is sometimes thought that some distinctively indexical kind of content is needed to characterise those states. | |
| From: Cappelen,H/Dever,Josh (The Inessential Indexical [2013], 01.4) | |
| A reaction: They are summarising this view precisely so that they can oppose it, and I think they are right. |
| 18426 | All information is objective, and purely indexical information is not much use [Cappelen/Dever] |
| Full Idea: Fundamentally, all information is objective information. ...[176] What we want is fully portable information, and information that co-ordinates on the world, rather than on us, is best suited for the task. | |
| From: Cappelen,H/Dever,Josh (The Inessential Indexical [2013], 10) | |
| A reaction: I agree entirely with their thesis. We just pick up information about ourselves, such as who and where we are, which is just like equivalent information about other people. It is isn't a special type of information. |
| 18427 | If some of our thought is tied to its context, it will be hard to communicate it [Cappelen/Dever] |
| Full Idea: It is bad news if some of our contents are essentially tied to particular contexts. ...If information needs to be assessed relative to some ur-context, later recipients won't know what to do with it. | |
| From: Cappelen,H/Dever,Josh (The Inessential Indexical [2013], 10) |
| 18428 | You don't remember your house interior just from an experienced viewpoint [Cappelen/Dever] |
| Full Idea: When you recall the look of the inside of your house ....where things are relative to one another is what persists in memory, not where they were relative to you when seen. | |
| From: Cappelen,H/Dever,Josh (The Inessential Indexical [2013], 10) | |
| A reaction: This seems to be a very telling example, though you could postulate some system which converts perspectival input into objective information. But why bother? We seek objective information, not perspectives. |
| 18429 | Our beliefs and desires are not organised around ourselves, but around the world [Cappelen/Dever] |
| Full Idea: Our view on the world is not primarily a view from a perspective. Our beliefs and desires are not organized around us. They are instead organized around the world itself. Our view is a view from everywhere. | |
| From: Cappelen,H/Dever,Josh (The Inessential Indexical [2013], 10) | |
| A reaction: Slipping in the claim that our desires are also organised around the world is not quite as persuasive as the claim about beliefs. If you want to draw a freehand straight line, focus on the far end of it. The world will guide your hand. |
| 18407 | Indexicality is not significantly connected to agency [Cappelen/Dever] |
| Full Idea: There are no interesting or distinctive explanatory connections between indexicality and agency. | |
| From: Cappelen,H/Dever,Josh (The Inessential Indexical [2013], 01.8) |
| 18413 | Fregeans can't agree on what 'senses' are [Cappelen/Dever] |
| Full Idea: There is little agreement among Fregeans about what senses are. | |
| From: Cappelen,H/Dever,Josh (The Inessential Indexical [2013], 04.5) | |
| A reaction: I don't take this to be sufficient grounds for dismissing Fregean senses. When we look into the workings of the linguistic mind, there seems little prospect of clarity or agreement. |
| 18417 | Possible worlds accounts of content are notoriously coarse-grained [Cappelen/Dever] |
| Full Idea: Possible worlds accounts of content are notoriously coarse-grained. They fail to distinguish between logical or mathematical truths, ..between metaphysical equivalences, ..between coreferentials, ..and between indexicals and non-indexicals. | |
| From: Cappelen,H/Dever,Josh (The Inessential Indexical [2013], 05.5) | |
| A reaction: [A nice summary, very compressed] |
| 18408 | Indexicals are just non-constant in meaning, and don't involve any special concepts [Cappelen/Dever] |
| Full Idea: Once the non-constant characters of expressions has been characterised, there is no further need for additional devices like 'first-person concepts' or 'demonstrative concepts'. | |
| From: Cappelen,H/Dever,Josh (The Inessential Indexical [2013], 01.7) | |
| A reaction: This seems to me to be a wonderfully liberating attack on this issue. There is a kind of creepy mysticism that has been allowed to accrue around indexicals, and it's nonsense. |
| 18414 | Fregeans say 'I' differs in reference, so it must also differ in sense [Cappelen/Dever] |
| Full Idea: Fregeans tend to treat as a fundamental tenet that sense determines reference; same sense, same reference. From that it follow trivially that indexicals don't have the same sense: different uses of 'I' have different referents, so sense must differ. | |
| From: Cappelen,H/Dever,Josh (The Inessential Indexical [2013], 04.6) | |
| A reaction: Interesting. Since it seems implausible that 'I' is profoundly different when two people use it, this seems to be a strong argument against Frege's distinction. But I rather like Frege's distinction, while being sceptical about 'I', so I'm baffled.... |
| 18423 | All indexicals can be expressed non-indexically [Cappelen/Dever] |
| Full Idea: Whatever can be expressed indexically could be expressed by non-indexical means. | |
| From: Cappelen,H/Dever,Josh (The Inessential Indexical [2013], 08.1) | |
| A reaction: This is the best summary of the thesis of their book. Indexicality in non-essential. |
| 18406 | The basic Kaplan view is that there is truth-conditional content, and contextual character [Cappelen/Dever] |
| Full Idea: In what we label 'Basic Kaplanianism', each of the sentences 'Smith is happy' and 'I am happy', as uttered by Smith, has two levels of meaning. The 'content' is a truth-conditional representation. The 'character' is a function from contexts to contents. | |
| From: Cappelen,H/Dever,Josh (The Inessential Indexical [2013], 01.6) | |
| A reaction: They give this as a minimal and plausible account of the situation, without reading huge significance into the indexical. I'm inclined to see the situation in terms of the underlying proposition containing both ingredients. |
| 18411 | It is proposed that a huge range of linguistic items are context-sensitive [Cappelen/Dever] |
| Full Idea: An enormous amount has been written about whether 'all', 'know', 'might', 'delicious', 'good', 'if, then', 'and', 'red', 'just', 'justified', 'probable', 'local', 'ready', and 'left-right' are context-sensitive. | |
| From: Cappelen,H/Dever,Josh (The Inessential Indexical [2013], 02.3) | |
| A reaction: The clearest way to approach these things is ask what the (informal) domain of quantification is for that particular context. The domain can shift in the course of a sentence. |
| 18420 | We deny that action involves some special class of beliefs [Cappelen/Dever] |
| Full Idea: Maybe there is a class of beliefs that plays a special role in the explanation of action. We have argued against the existence of such a class (or at least any interesting such class). | |
| From: Cappelen,H/Dever,Josh (The Inessential Indexical [2013], 06.2) | |
| A reaction: The main class which has been proposed is the one that involves indexical beliefs. I agree with this idea. |