49 ideas
| 14052 | Begin philosophy when you are young, and keep going when you are old [Epicurus] |
| Full Idea: Let no one delay the study of philosophy while young nor weary of it when old; for no one is either too young or too old for the health of the soul. | |
| From: Epicurus (Letter to Menoeceus [c.291 BCE], 122) | |
| A reaction: I agree with this on both accounts. I think the correct age to begin the study of philosophy is four, and it is vital to continue its study up to the point where you can no longer remember your own name. 'Health of the soul' sounds right too. |
| 12223 | It is a fallacy to explain the obscure with the even more obscure [Hale/Wright] |
| Full Idea: The fallacy of 'ad obscurum per obscurius' is to explain the obscure by appeal to what is more obscure. | |
| From: B Hale / C Wright (The Metaontology of Abstraction [2009], §3) | |
| A reaction: Not strictly a fallacy, so much as an example of inadequate explanation, along with circularity and infinite regresses. |
| 13252 | Some truths have true negations [Beall/Restall] |
| Full Idea: Dialetheism is the view that some truths have true negations. | |
| From: JC Beall / G Restall (Logical Pluralism [2006], 7.4) | |
| A reaction: The important thing to remember is that they are truths. Thus 'Are you feeling happy?' might be answered 'Yes and no'. |
| 13247 | A truthmaker is an object which entails a sentence [Beall/Restall] |
| Full Idea: The truthmaker thesis is that an object is a truthmaker for a sentence if and only if its existence entails the sentence. | |
| From: JC Beall / G Restall (Logical Pluralism [2006], 5.5.3) | |
| A reaction: The use of the word 'object' here is even odder than usual, and invites many questions. And the 'only if' seems peculiar, since all sorts of things can make a sentence true. 'There is someone in the house' for example. |
| 13249 | (∀x)(A v B) |- (∀x)A v (∃x)B) is valid in classical logic but invalid intuitionistically [Beall/Restall] |
| Full Idea: The inference of 'distribution' (∀x)(A v B) |- (∀x)A v (∃x)B) is valid in classical logic but invalid intuitionistically. It is straightforward to construct a 'stage' at which the LHS is true but the RHS is not. | |
| From: JC Beall / G Restall (Logical Pluralism [2006], 6.1.2) | |
| A reaction: This seems to parallel the iterative notion in set theory, that you must construct your hierarchy. All part of the general 'constructivist' approach to things. Is some kind of mad platonism the only alternative? |
| 13243 | Excluded middle must be true for some situation, not for all situations [Beall/Restall] |
| Full Idea: Relevant logic endorses excluded middle, ..but says instances of the law may fail. Bv¬B is true in every situation that settles the matter of B. It is necessary that there is some such situation. | |
| From: JC Beall / G Restall (Logical Pluralism [2006], 5.2) | |
| A reaction: See next idea for the unusual view of necessity on which this rests. It seems easier to assert something about all situations than just about 'some' situation. |
| 13242 | It's 'relevantly' valid if all those situations make it true [Beall/Restall] |
| Full Idea: The argument from P to A is 'relevantly' valid if and only if, for every situation in which each premise in P is true, so is A. | |
| From: JC Beall / G Restall (Logical Pluralism [2006], 5.2) | |
| A reaction: I like the idea that proper inference should have an element of relevance to it. A falsehood may allow all sorts of things, without actually implying them. 'Situations' sound promising here. |
| 13245 | Relevant consequence says invalidity is the conclusion not being 'in' the premises [Beall/Restall] |
| Full Idea: Relevant consequence says the conclusion of a relevantly invalid argument is not 'carried in' the premises - it does not follow from the premises. | |
| From: JC Beall / G Restall (Logical Pluralism [2006], 5.3.3) | |
| A reaction: I find this appealing. It need not invalidate classical logic. It is just a tougher criterion which is introduced when you want to do 'proper' reasoning, instead of just playing games with formal systems. |
| 13246 | Relevant logic does not abandon classical logic [Beall/Restall] |
| Full Idea: We have not abandoned classical logic in our acceptance of relevant logic. | |
| From: JC Beall / G Restall (Logical Pluralism [2006], 5.4) | |
| A reaction: It appears that classical logic is straightforwardly accepted, but there is a difference of opinion over when it is applicable. |
| 13254 | A doesn't imply A - that would be circular [Beall/Restall] |
| Full Idea: We could reject the inference from A to itself (on grounds of circularity). | |
| From: JC Beall / G Restall (Logical Pluralism [2006], 8) | |
| A reaction: [Martin-Meyer System] 'It's raining today'. 'Are you implying that it is raining today?' 'No, I'm SAYING it's raining today'. Logicians don't seem to understand the word 'implication'. Logic should capture how we reason. Nice proposal. |
| 13255 | Relevant logic may reject transitivity [Beall/Restall] |
| Full Idea: Some relevant logics reject transitivity, but we defend the classical view. | |
| From: JC Beall / G Restall (Logical Pluralism [2006], 8) | |
| A reaction: [they cite Neil Tennant for this view] To reject transitivity (A?B ? B?C ? A?C) certainly seems a long way from classical logic. But in everyday inference Tennant's idea seems good. The first premise may be irrelevant to the final conclusion. |
| 13250 | Free logic terms aren't existential; classical is non-empty, with referring names [Beall/Restall] |
| Full Idea: A logic is 'free' to the degree it refrains from existential import of its singular and general terms. Classical logic must have non-empty domain, and each name must denote in the domain. | |
| From: JC Beall / G Restall (Logical Pluralism [2006], 7.1) | |
| A reaction: My intuition is that logic should have no ontology at all, so I like the sound of 'free' logic. We can't say 'Pegasus does not exist', and then reason about Pegasus just like any other horse. |
| 13235 | Logic studies consequence; logical truths are consequences of everything, or nothing [Beall/Restall] |
| Full Idea: Nowadays we think of the consequence relation itself as the primary subject of logic, and view logical truths as degenerate instances of this relation. Logical truths follow from any set of assumptions, or from no assumptions at all. | |
| From: JC Beall / G Restall (Logical Pluralism [2006], 2.2) | |
| A reaction: This seems exactly right; the alternative is the study of necessities, but that may not involve logic. |
| 13238 | Syllogisms are only logic when they use variables, and not concrete terms [Beall/Restall] |
| Full Idea: According to the Peripatetics (Aristotelians), only syllogistic laws stated in variables belong to logic, and not their applications to concrete terms. | |
| From: JC Beall / G Restall (Logical Pluralism [2006], 2.5) | |
| A reaction: [from Lukasiewicz] Seems wrong. I take it there are logical relations between concrete things, and the variables are merely used to describe these relations. Variables lack the internal powers to drive logical necessities. Variables lack essence! |
| 13234 | The view of logic as knowing a body of truths looks out-of-date [Beall/Restall] |
| Full Idea: Through much of the 20th century the conception of logic was inherited from Frege and Russell, as knowledge of a body of logical truths, as arithmetic or geometry was a knowledge of truths. This is odd, and a historical anomaly. | |
| From: JC Beall / G Restall (Logical Pluralism [2006], 2.2) | |
| A reaction: Interesting. I have always taken this idea to be false. I presume logic has minimal subject matter and truths, and preferably none at all. |
| 13232 | Logic studies arguments, not formal languages; this involves interpretations [Beall/Restall] |
| Full Idea: Logic does not study formal languages for their own sake, which is formal grammar. Logic evaluates arguments, and primarily considers formal languages as interpreted. | |
| From: JC Beall / G Restall (Logical Pluralism [2006], 2.1) | |
| A reaction: Hodges seems to think logic just studies formal languages. The current idea strikes me as a much more sensible view. |
| 13241 | The model theory of classical predicate logic is mathematics [Beall/Restall] |
| Full Idea: The model theory of classical predicate logic is mathematics if anything is. | |
| From: JC Beall / G Restall (Logical Pluralism [2006], 4.2.1) | |
| A reaction: This is an interesting contrast to the claim of logicism, that mathematics reduces to logic. This idea explains why students of logic are surprised to find themselves involved in mathematics. |
| 13253 | There are several different consequence relations [Beall/Restall] |
| Full Idea: We are pluralists about logical consequence because we take there to be a number of different consequence relations, each reflecting different precisifications of the pre-theoretic notion of deductive logical consequence. | |
| From: JC Beall / G Restall (Logical Pluralism [2006], 8) | |
| A reaction: I don't see how you avoid the slippery slope that leads to daft logical rules like Prior's 'tonk' (from which you can infer anything you like). I say that nature imposes logical conquence on us - but don't ask me to prove it. |
| 13240 | A sentence follows from others if they always model it [Beall/Restall] |
| Full Idea: The sentence X follows logically from the sentences of the class K if and only if every model of the class K is also a model of the sentence X. | |
| From: JC Beall / G Restall (Logical Pluralism [2006], 3.2) | |
| A reaction: This why the symbol |= is often referred to as 'models'. |
| 12230 | Singular terms refer if they make certain atomic statements true [Hale/Wright] |
| Full Idea: Anyone should agree that a justification for regarding a singular term as having objectual reference is provided just as soon as one has justification for regarding as true certain atomic statements in which it functions as a singular term. | |
| From: B Hale / C Wright (The Metaontology of Abstraction [2009], §9) | |
| A reaction: The meat of this idea is hidden in the word 'certain'. See Idea 10314 for Hale's explanation. Without that, the proposal strikes me as absurd. |
| 13236 | Logical truth is much more important if mathematics rests on it, as logicism claims [Beall/Restall] |
| Full Idea: If mathematical truth reduces to logical truth then it is important what counts as logically true, …but if logicism is not a going concern, then the body of purely logical truths will be less interesting. | |
| From: JC Beall / G Restall (Logical Pluralism [2006], 2.2) | |
| A reaction: Logicism would only be one motivation for pursuing logical truths. Maybe my new 'Necessitism' will derive the Peano Axioms from broad necessary truths, rather than from logic. |
| 13237 | Preface Paradox affirms and denies the conjunction of propositions in the book [Beall/Restall] |
| Full Idea: The Paradox of the Preface is an apology, that you are committed to each proposition in the book, but admit that collectively they probably contain a mistake. There is a contradiction, of affirming and denying the conjunction of propositions. | |
| From: JC Beall / G Restall (Logical Pluralism [2006], 2.4) | |
| A reaction: This seems similar to the Lottery Paradox - its inverse perhaps. Affirm all and then deny one, or deny all and then affirm one? |
| 12225 | Neo-Fregeanism might be better with truth-makers, rather than quantifier commitment [Hale/Wright] |
| Full Idea: A third way has been offered to 'make sense' of neo-Fregeanism: we should reject Quine's well-known criterion of ontological commitment in favour of one based on 'truth-maker theory'. | |
| From: B Hale / C Wright (The Metaontology of Abstraction [2009], §4 n19) | |
| A reaction: [The cite Ross Cameron for this] They reject this proposal, on the grounds that truth-maker theory is not sufficient to fix the grounding truth-conditions of statements. |
| 12224 | Are neo-Fregeans 'maximalists' - that everything which can exist does exist? [Hale/Wright] |
| Full Idea: It is claimed that neo-Fregeans are committed to 'maximalism' - that whatever can exist does. | |
| From: B Hale / C Wright (The Metaontology of Abstraction [2009], §4) | |
| A reaction: [The cite Eklund] They observe that maximalism denies contingent non-existence (of the Ł20 note I haven't got). There seems to be the related problem of 'hyperinflation', that if abstract objects are generated logically, the process is unstoppable. |
| 12226 | The identity of Pegasus with Pegasus may be true, despite the non-existence [Hale/Wright] |
| Full Idea: Identity is sometimes read so that 'Pegasus is Pegasus' expresses a truth, the non-existence of any winged horse notwithstanding. | |
| From: B Hale / C Wright (The Metaontology of Abstraction [2009], §5) | |
| A reaction: This would give you ontological commitment to truth, without commitment to existence. It undercuts the use of identity statements as the basis of existence claims, which was Frege's strategy. |
| 12229 | Maybe we have abundant properties for semantics, and sparse properties for ontology [Hale/Wright] |
| Full Idea: There is a compatibilist view which says that it is for the abundant properties to play the role of 'bedeutungen' in semantic theory, and the sparse ones to address certain metaphysical concerns. | |
| From: B Hale / C Wright (The Metaontology of Abstraction [2009], §9) | |
| A reaction: Only a philosopher could live with the word 'property' having utterly different extensions in different areas of discourse. They similarly bifurcate words like 'object' and 'exist'. Call properties 'quasi-properties' and I might join in. |
| 18443 | A successful predicate guarantees the existence of a property - the way of being it expresses [Hale/Wright] |
| Full Idea: The good standing of a predicate is already trivially sufficient to ensure the existence of an associated property, a (perhaps complex) way of being which the predicate serves to express. | |
| From: B Hale / C Wright (The Metaontology of Abstraction [2009], §9) | |
| A reaction: 'Way of being' is interesting. Is 'being near Trafalgar Sq' a way of being? I take properties to be 'features', which seems to give a clearer way of demarcating them. They say they are talking about 'abundant' (rather than 'sparse') properties. |
| 13244 | Relevant necessity is always true for some situation (not all situations) [Beall/Restall] |
| Full Idea: In relevant logic, the necessary truths are not those which are true in every situation; rather, they are those for which it is necessary that there is a situation making them true. | |
| From: JC Beall / G Restall (Logical Pluralism [2006], 5.2) | |
| A reaction: This seems to rest on the truthmaker view of such things, which I find quite attractive (despite Merricks's assault). Always ask what is making some truth necessary. This leads you to essences. |
| 14062 | Sooner follow mythology, than accept the 'fate' of natural philosophers [Epicurus] |
| Full Idea: It would be better to follow the stories told about the gods than to be a slave to the fate of the natural philosophers. | |
| From: Epicurus (Letter to Menoeceus [c.291 BCE], 134) | |
| A reaction: At this point in history there is a blurring between autonomous decisions and what we now call free will, and also between fate and determinism, which we try to keep distinct. |
| 1837 | We should not refer things to irresponsible necessity, but either to fortune or to our own will [Epicurus] |
| Full Idea: The best men have no belief in necessity (set up by some as mistress of all), but refer some things to fortune, some to ourselves, because necessity is irresponsible, and fortune is unstable, while our own will is free. | |
| From: Epicurus (Letter to Menoeceus [c.291 BCE], 133), quoted by Diogenes Laertius - Lives of Eminent Philosophers 10.27 |
| 13239 | Judgement is always predicating a property of a subject [Beall/Restall] |
| Full Idea: All judgement, for Kant, is essentially the predication of some property to some subject. | |
| From: JC Beall / G Restall (Logical Pluralism [2006], 2.5) | |
| A reaction: Presumably the denial of a predicate could be a judgement, or the affirmation of ambiguous predicates? |
| 12227 | Abstractionism needs existential commitment and uniform truth-conditions [Hale/Wright] |
| Full Idea: Abstractionism needs a face-value, existentially committed reading of the terms occurring on the left-hand sides together with sameness of truth-conditions across the biconditional. | |
| From: B Hale / C Wright (The Metaontology of Abstraction [2009], §5) | |
| A reaction: They employ 'abstractionism' to mean their logical Fregean strategy for defining abstractions, not to mean the older psychological account. Thus the truth-conditions for being 'parallel' and for having the 'same direction' must be consistent. |
| 12228 | Equivalence abstraction refers to objects otherwise beyond our grasp [Hale/Wright] |
| Full Idea: Abstraction principles purport to introduce fundamental means of reference to a range of objects, to which there is accordingly no presumption that we have any prior or independent means of reference. | |
| From: B Hale / C Wright (The Metaontology of Abstraction [2009], §8) | |
| A reaction: There's the rub! They make it sound like a virtue, that we open up yet another heaven of abstract toys to play with. As fictions, they are indeed exciting new fun. As platonic discoveries they strike me as Cloud-Cuckoo Land. |
| 12231 | Reference needs truth as well as sense [Hale/Wright] |
| Full Idea: It takes, over and above the possession of sense, the truth of relevant contexts to ensure reference. | |
| From: B Hale / C Wright (The Metaontology of Abstraction [2009], §9) | |
| A reaction: Reference purely through sense was discredited by Kripke. The present idea challenges Kripke's baptismal realist approach. How do you 'baptise' an abstract object? But isn't reference needed prior to the establishment of truth? |
| 13248 | We can rest truth-conditions on situations, rather than on possible worlds [Beall/Restall] |
| Full Idea: Situation semantics is a variation of the truth-conditional approach, taking the salient unit of analysis not to be the possible world, or some complete consistent index, but rather the more modest 'situation'. | |
| From: JC Beall / G Restall (Logical Pluralism [2006], 5.5.4) | |
| A reaction: When I read Davidson (and implicitly Frege) this is what I always assumed was meant. The idea that worlds are meant has crept in to give truth conditions for modal statements. Hence situation semantics must cover modality. |
| 13233 | Propositions commit to content, and not to any way of spelling it out [Beall/Restall] |
| Full Idea: Our talk of propositions expresses commitment to the general notion of content, without a commitment to any particular way of spelling this out. | |
| From: JC Beall / G Restall (Logical Pluralism [2006], 2.1) | |
| A reaction: As a fan of propositions I like this. It leaves open the question of whether the content belongs to the mind or the language. Animals entertain propositions, say I. |
| 1836 | Prudence is more valuable than philosophy, because it avoids confusions of the soul [Epicurus] |
| Full Idea: The greatest good in avoiding confusion of the soul is prudence [phronesis], on which account prudence is something more valuable than even philosophy. | |
| From: Epicurus (Letter to Menoeceus [c.291 BCE], 132), quoted by Diogenes Laertius - Lives of Eminent Philosophers 10.27 |
| 14061 | Our own choices are autonomous, and the basis for praise and blame [Epicurus] |
| Full Idea: What occurs by our own agency is autonomous, and it is to this that praise and blame are attached. | |
| From: Epicurus (Letter to Menoeceus [c.291 BCE], 133) | |
| A reaction: I don't think this should be understand as an assertion of free will in the modern sense. The 'swerve' of the atoms just means that decisions can arise out of us - not that they are somehow outside of nature. |
| 14055 | The wisdom that produces a good life also produces a good death [Epicurus] |
| Full Idea: The same kind of practice produces a good life and a good death. | |
| From: Epicurus (Letter to Menoeceus [c.291 BCE], 126) | |
| A reaction: This is the kind of old fashioned observation which we would do well to hang on to. The ideal of dying well has vanished from our culture. |
| 14054 | Fearing death is absurd, because we are not present when it occurs [Epicurus] |
| Full Idea: Death, the most frightening of bad things, is nothing to us; since when we exist, death is not yet present, and when death is present, then we do not exist. | |
| From: Epicurus (Letter to Menoeceus [c.291 BCE], 125) | |
| A reaction: This is a fairly accurate observation. To fear not being in this life is a bit like fearing not being in Vancouver next Tuesday. It also involves the paradox of the present moment. E.g. Idea 1904. |
| 14053 | It is absurd to fear the pain of death when you are not even facing it [Epicurus] |
| Full Idea: He is a fool who says that he fears death not because it will be painful when present but because it is painful when it is still to come. | |
| From: Epicurus (Letter to Menoeceus [c.291 BCE], 125) | |
| A reaction: Not very plausible, I'm afraid. It provides a good argument in favour of smoking, if the lung cancer is far in the future. Paralysing fear is daft, but some remote fears should be heeded. |
| 14058 | Pleasure is the goal, but as lack of pain and calm mind, not as depraved or greedy pleasure [Epicurus] |
| Full Idea: When we say that pleasure is the goal we do not mean the pleasures of the profligate or the pleasures of consumption, but rather the lack of pain in the body and disturbance in the soul. | |
| From: Epicurus (Letter to Menoeceus [c.291 BCE], 131) | |
| A reaction: I don't really understand the aspiration to a 'calm mind'. No one likes stress, but total calmness sounds close to non-existence. The mean! There is no achievement without pain. |
| 1833 | Pleasure is the first good in life [Epicurus] |
| Full Idea: Pleasure is the beginning and end of living happily, and we recognise this as the first good. | |
| From: Epicurus (Letter to Menoeceus [c.291 BCE], 128) | |
| A reaction: We might enquire what we would live for if our capacities for pleasure were surgically removed. Would we still experience intellectual curiosity, or an aspiration to some cold and remote goodness? |
| 14057 | All pleasures are good, but it is not always right to choose them [Epicurus] |
| Full Idea: Every pleasure is a good thing, since it has a nature congenial to us, but not every one is to be chosen, just as every pain is a bad thing, but not every one is such as to be always avoided. | |
| From: Epicurus (Letter to Menoeceus [c.291 BCE], 129) | |
| A reaction: This kind of sensible remark would be wholly endorsed by Bentham and Mill. This fits in with the excellent distinction between what is right and what is good. |
| 14063 | Sooner a good decision going wrong, than a bad one turning out for the good [Epicurus] |
| Full Idea: It is better for a good decision not to turn out right in action than for a bad decision to turn out right because of chance. | |
| From: Epicurus (Letter to Menoeceus [c.291 BCE], 135) | |
| A reaction: This sounds right, and on the whole the law agrees. Notice that what we need is a 'good decision', and not just to 'mean well'. The well-meaning fool is wicked. I am opposed to consequentialism, and agree with this idea. |
| 14059 | The best life is not sensuality, but rational choice and healthy opinion [Epicurus] |
| Full Idea: It is not drinking bouts or enjoying boys and women or consuming fish which produces the pleasant life, but sober calculation which searches out reasons for every choice, and drives out opinions which produce turmoil of the soul. | |
| From: Epicurus (Letter to Menoeceus [c.291 BCE], 132) | |
| A reaction: This more or less sums up what I would call the philosophical life. Spontaneity is good, and some pleasures are killed by excessive thought, but on the whole actions are always better if good reasons are found, and error brings chaos. |
| 1835 | True pleasure is not debauchery, but freedom from physical and mental pain [Epicurus] |
| Full Idea: When we say that pleasure is the chief good, we do not mean debauchery, but freedom of the body from pain, and of the soul from confusion…. which requires sober contemplation. | |
| From: Epicurus (Letter to Menoeceus [c.291 BCE], 131), quoted by Diogenes Laertius - Lives of Eminent Philosophers 10.27 | |
| A reaction: I'm not clear how lack of pain and confusion counts as pleasure. Also the concepts of debauchery held by the puritan and the sybarite are wildly different. |
| 14056 | We only need pleasure when we have the pain of desire [Epicurus] |
| Full Idea: We are in need of pleasure only when we are in pain because of the absence of pleasure, and when we are not in pain, then we no longer need pleasure. | |
| From: Epicurus (Letter to Menoeceus [c.291 BCE], 128) | |
| A reaction: This Buddhist aspiration to eliminate desire has no appeal for me. It just sounds like a recipe for boredom, and an aversion to risk-taking. Start by asking what is best in life; it inevitably involves pleasure of some sort. Anyway, desire isn't painful. |
| 14060 | Prudence is the greatest good, and more valuable than philosophy, because it produces virtue [Epicurus] |
| Full Idea: Prudence is the principle of the rational life and is the greatest good. That is why prudence is more valuable than philosophy, for prudence is the source of all the other virtues. | |
| From: Epicurus (Letter to Menoeceus [c.291 BCE], 132) | |
| A reaction: ['prudence' will be Greek 'phronesis']The interest of this is that it is almost copied straight out of Aristotle's Ethics. Epicurus was an opponent of the Peripatetics, but greatly influenced by them. |