47 ideas
| 1887 | You cannot divide anything into many parts, because after the first division you are no longer dividing the original [Sext.Empiricus] |
| Full Idea: You cannot divide anything (such as the decad) into many parts, because as soon as you separate the first part, you are no longer dividing the original. | |
| From: Sextus Empiricus (Outlines of Pyrrhonism [c.180], II.215) |
| 1885 | Proof moves from agreed premises to a non-evident inference [Sext.Empiricus] |
| Full Idea: Dogmatists define proof as "an argument which, by means of agreed premises, reveals by way of deduction a nonevident inference". | |
| From: Sextus Empiricus (Outlines of Pyrrhonism [c.180], II.135) |
| 10928 | Maybe we can quantify modally if the objects are intensional, but it seems unlikely [Quine] |
| Full Idea: Perhaps there is no objection to quantifying into modal contexts as long as the values of any variables thus quantified are limited to intensional objects, but they also lead to disturbing examples. | |
| From: Willard Quine (Reference and Modality [1953], §3) | |
| A reaction: [Quine goes on to give his examples] I take it that possibilities are features of actual reality, not merely objects of thought. The problem is that they are harder to know than actual objects. |
| 12196 | A valid hypothetical syllogism is 'that which does not begin with a truth and end with a falsehood' [Sext.Empiricus] |
| Full Idea: Philo (of Megara) says that a valid hypothetical syllogism is 'that which does not begin with a truth and end with a falsehood,' as for instance the syllogism 'If it is day, I converse,' when in fact it is day and I am conversing. | |
| From: Sextus Empiricus (Outlines of Pyrrhonism [c.180], II.110) | |
| A reaction: Russell endorses this, and Rumfitt quotes it as the classic case of denying that there is any modal aspect (such as 'logical necessity') involved in logical consequence. He labels it 'material or Philonian consequence'. |
| 10925 | Failure of substitutivity shows that a personal name is not purely referential [Quine] |
| Full Idea: Failure of substitutivity shows that the occurrence of a personal name is not purely referential. | |
| From: Willard Quine (Reference and Modality [1953], §1) | |
| A reaction: I don't think I understand the notion of a name being 'purely' referential, as if it somehow ceased to be a word, and was completely transparent to the named object. |
| 10926 | Quantifying into referentially opaque contexts often produces nonsense [Quine] |
| Full Idea: If to a referentially opaque context of a variable we apply a quantifier, with the intention that it govern that variable from outside the referentially opaque context, then what we commonly end up with is unintended sense or nonsense. | |
| From: Willard Quine (Reference and Modality [1953], §2) |
| 1902 | Since Socrates either died when he was alive (a contradiction) or died when he was dead (meaningless), he didn't die [Sext.Empiricus] |
| Full Idea: If Socrates died, he died either when he lived or when he died; so he was either dead when he was alive, or he was twice dead when he was dead. So he didn't die. | |
| From: Sextus Empiricus (Outlines of Pyrrhonism [c.180], III.111) | |
| A reaction: One of my favourites. Of all the mysteries facing us, the one that boggles me most is how anything can happen in the 'present' moment, if the present is just the overlap point between past and future. |
| 10930 | Quantification into modal contexts requires objects to have an essence [Quine] |
| Full Idea: A reversion to Aristotelian essentialism is required if quantification into modal contexts is to be insisted on. An object must be seen as having some of its traits necessarily. | |
| From: Willard Quine (Reference and Modality [1953], §3) | |
| A reaction: This thought leads directly to Kripke's proposal of rigid designation of objects (and Lewis response of counterparts), which really gets modal logic off the ground. Quine's challenge remains - the modal logic entails a huge metaphysical commitment. |
| 14645 | To be necessarily greater than 7 is not a trait of 7, but depends on how 7 is referred to [Quine] |
| Full Idea: To be necessarily greater than 7 is not a trait of a number, but depends on the manner of referring to the number. | |
| From: Willard Quine (Reference and Modality [1953], §2) | |
| A reaction: The most concise quotation of Quine's objection to 'de re' modality. The point is whether the number might have been referred to as 'the number of planets'. So many of these problems are solved by fixing unambiguous propositions first. |
| 9201 | Whether 9 is necessarily greater than 7 depends on how '9' is described [Quine, by Fine,K] |
| Full Idea: Quine's metaphysical argument is that if 9 is 7+2 the number 9 will be necessarily greater than 7, but when 9 is described as the number of planets, the number will not be necessarily greater than 7. The necessity depends on how it is described. | |
| From: report of Willard Quine (Reference and Modality [1953]) by Kit Fine - Intro to 'Modality and Tense' p. 3 | |
| A reaction: Thus necessity would be entirely 'de dicto' and not 'de re'. It sounds like a feeble argument. If I describe the law of identity (a=a) as 'my least favourite logical principle', that won't make it contingent. Describe 9, or refer to it? See Idea 9203. |
| 10927 | Necessity only applies to objects if they are distinctively specified [Quine] |
| Full Idea: Necessity does not properly apply to the fulfilment of conditions by objects (such as the number which numbers the planets), apart from special ways of specifying them. | |
| From: Willard Quine (Reference and Modality [1953], §3) | |
| A reaction: This appears to say that the only necessity is 'de dicto', and that there is no such thing as 'de re' necessity (of the thing in itself). How can Quine deny that there might be de re necessities? His point is epistemological - how can we know them? |
| 9203 | We can't quantify in modal contexts, because the modality depends on descriptions, not objects [Quine, by Fine,K] |
| Full Idea: 'Necessarily 9>7' may be true while the sentence 'necessarily the number of planets < 7' is false, even though it is obtained by substituting a coreferential term. So quantification in these contexts is unintelligible, without a clear object. | |
| From: report of Willard Quine (Reference and Modality [1953]) by Kit Fine - Intro to 'Modality and Tense' p. 4 | |
| A reaction: This is Quine's second argument against modality. See Idea 9201 for his first. Fine attempts to refute it. The standard reply seems to be to insist that 9 must therefore be an object, which pushes materialist philosophers into reluctant platonism. |
| 1889 | If an argument has an absurd conclusion, we should not assent to the absurdity, but avoid the absurd argument [Sext.Empiricus] |
| Full Idea: If an argument leads to confessedly absurd conclusions, we should not assent to the absurdity just because of the argument, but avoid the argument because of the absurdity. | |
| From: Sextus Empiricus (Outlines of Pyrrhonism [c.180], II.252) | |
| A reaction: cf. G.E.Moore. Denying that you have a hand seems to be an absurdity, but I'm not sure if I can give a criterion for absurdity in such a case. One person's modus ponens is another person's modus tollens. |
| 1871 | Whether honey is essentially sweet may be doubted, as it is a matter of judgement rather than appearance [Sext.Empiricus] |
| Full Idea: Honey appears to sceptics to be sweet, but whether it is also sweet in its essence is for us a matter of doubt, since this is not an appearance but a judgement. | |
| From: Sextus Empiricus (Outlines of Pyrrhonism [c.180], I.20) |
| 1883 | How can the intellect know if sensation is reliable if it doesn't directly see external objects? [Sext.Empiricus] |
| Full Idea: Just as you can't know if a portrait of Socrates is good without seeing the man, so when the intellect gazes on sensations but not the external objects it cannot know whether they are similar. | |
| From: Sextus Empiricus (Outlines of Pyrrhonism [c.180], II.75) |
| 1890 | We distinguish ambiguities by seeing what is useful [Sext.Empiricus] |
| Full Idea: It is the experience of what is useful in each affair that brings about the distinguishing of ambiguities. | |
| From: Sextus Empiricus (Outlines of Pyrrhonism [c.180], II.258) |
| 1870 | The basis of scepticism is the claim that every proposition has an equal opposing proposition [Sext.Empiricus] |
| Full Idea: The main basic principle of the sceptic system is that of opposing to every proposition an equal proposition. | |
| From: Sextus Empiricus (Outlines of Pyrrhonism [c.180], I.12) |
| 1882 | The necks of doves appear different in colour depending on the angle of viewing [Sext.Empiricus] |
| Full Idea: The necks of doves appear different in hue according to the differences in the angle of inclination. | |
| From: Sextus Empiricus (Outlines of Pyrrhonism [c.180], I.120) |
| 1881 | The same oar seems bent in water and straight when out of it [Sext.Empiricus] |
| Full Idea: The same oar seems bent when in the water but straight when out of the water. | |
| From: Sextus Empiricus (Outlines of Pyrrhonism [c.180], I.119) |
| 1872 | The same tower appears round from a distance, but square close at hand [Sext.Empiricus] |
| Full Idea: The same tower appears round from a distance, but square close at hand. | |
| From: Sextus Empiricus (Outlines of Pyrrhonism [c.180], I.32) |
| 1873 | If we press the side of an eyeball, objects appear a different shape [Sext.Empiricus] |
| Full Idea: When we press the eyeball at one side the forms, figures and sizes of the objects appear oblong and narrow. | |
| From: Sextus Empiricus (Outlines of Pyrrhonism [c.180], I.47) |
| 1874 | How can we judge between our impressions and those of other animals, when we ourselves are involved? [Sext.Empiricus] |
| Full Idea: We cannot judge between our own impressions and those of other animals, because we ourselves are involved in the dispute. | |
| From: Sextus Empiricus (Outlines of Pyrrhonism [c.180], I.59) |
| 1878 | Water that seems lukewarm can seem very hot on inflamed skin [Sext.Empiricus] |
| Full Idea: The same water which seems very hot when poured on inflamed spots seems lukewarm to us. | |
| From: Sextus Empiricus (Outlines of Pyrrhonism [c.180], I.101) |
| 1880 | Some actions seem shameful when sober but not when drunk [Sext.Empiricus] |
| Full Idea: Actions which seem shameful to us when sober do not seem shameful when drunk. | |
| From: Sextus Empiricus (Outlines of Pyrrhonism [c.180], I.109) |
| 1877 | If we had no hearing or sight, we would assume no sound or sight exists, so there may be unsensed qualities [Sext.Empiricus] |
| Full Idea: A man with touch, taste and smell, but no hearing or sight, will assume nothing audible or visible exists, so maybe an apple has qualities which we have no senses to perceive. | |
| From: Sextus Empiricus (Outlines of Pyrrhonism [c.180], I.96) |
| 1879 | Sickness is perfectly natural to the sick, so their natural perceptions should carry some weight [Sext.Empiricus] |
| Full Idea: Health is natural for the healthy but unnatural for the sick, and sickness is unnatural for the healthy but natural for the sick, so we must give credence to the natural perceptions of the sick. | |
| From: Sextus Empiricus (Outlines of Pyrrhonism [c.180], I.103) |
| 1876 | If we enjoy different things, presumably we receive different impressions [Sext.Empiricus] |
| Full Idea: The enjoyment of different things is an indication that we get varying impressions from the underlying objects. | |
| From: Sextus Empiricus (Outlines of Pyrrhonism [c.180], I.80) |
| 1910 | With us it is shameful for men to wear earrings, but among Syrians it is considered noble [Sext.Empiricus] |
| Full Idea: It is a shameful thing with us for men to wear earrings, but among some of the barbarians, such as the Syrians, it is a token of nobility. | |
| From: Sextus Empiricus (Outlines of Pyrrhonism [c.180], III.203) |
| 1911 | Even if all known nations agree on a practice, there may be unknown nations which disagree [Sext.Empiricus] |
| Full Idea: Even among practices on which all known cultures are agreed, disagreement about them may possibly exist amongst some of the nations which are unknown to us. | |
| From: Sextus Empiricus (Outlines of Pyrrhonism [c.180], III.234) |
| 1886 | If you don't view every particular, you may miss the one which disproves your universal induction [Sext.Empiricus] |
| Full Idea: Induction cannot establish the universal by means of the particular, since limited particulars may omit crucial examples which disprove the universal, and infinite particulars are impossible to know. | |
| From: Sextus Empiricus (Outlines of Pyrrhonism [c.180], II.204) |
| 1884 | If we utter three steps of a logical argument, they never exist together [Sext.Empiricus] |
| Full Idea: If we say "If day exists, lights exists", and then "day exists", and then "light exists", then parts of the judgement never exist together, and so the whole judgement will have no real existence. | |
| From: Sextus Empiricus (Outlines of Pyrrhonism [c.180], II.109) |
| 468 | Musical performance can reveal a range of virtues [Damon of Ath.] |
| Full Idea: In singing and playing the lyre, a boy will be likely to reveal not only courage and moderation, but also justice. | |
| From: Damon (fragments/reports [c.460 BCE], B4), quoted by (who?) - where? |
| 1894 | Some say that causes are physical, some say not [Sext.Empiricus] |
| Full Idea: Some affirm cause to be corporeal, some incorporeal. | |
| From: Sextus Empiricus (Outlines of Pyrrhonism [c.180], III.14) |
| 1897 | Knowing an effect results from a cause means knowing that the cause belongs with the effect, which is circular [Sext.Empiricus] |
| Full Idea: To know an effect belongs to a cause, we must also know that that cause belongs to that effect, and this is circular. | |
| From: Sextus Empiricus (Outlines of Pyrrhonism [c.180], III.21) |
| 1898 | Cause can't exist before effect, or exist at the same time, so it doesn't exist [Sext.Empiricus] |
| Full Idea: If cause neither subsists before its effect, nor subsists along with it, nor does the effect precede the cause, it would seem that it has no substantial existence at all. | |
| From: Sextus Empiricus (Outlines of Pyrrhonism [c.180], III.27) |
| 1896 | If there were no causes then everything would have been randomly produced by everything [Sext.Empiricus] |
| Full Idea: If causes were non-existent everything would have been produced by everything, and at random. | |
| From: Sextus Empiricus (Outlines of Pyrrhonism [c.180], III.18) |
| 1895 | Causes are either equal to the effect, or they link equally with other causes, or they contribute slightly [Sext.Empiricus] |
| Full Idea: The majority say causes are immediate (when they are directly proportional to effects), or associate (making an equal contribution to effects), or cooperant (making a slight contribution). | |
| From: Sextus Empiricus (Outlines of Pyrrhonism [c.180], III.15) |
| 10931 | We can't say 'necessarily if x is in water then x dissolves' if we can't quantify modally [Quine] |
| Full Idea: To say an object is soluble in water is to say that it would dissolve if it were in water,..which implies that 'necessarily if x is in water then x dissolves'. Yet we do not know if there is a suitable sense of 'necessarily' into which we can so quantify. | |
| From: Willard Quine (Reference and Modality [1953], §4) | |
| A reaction: This is why there has been a huge revival of scientific essentialism - because Krike seems to offer exacty the account which Quine said was missing. So can you have modal logic without rigid designation? |
| 1901 | If all atoms, times and places are the same, everything should move with equal velocity [Sext.Empiricus] |
| Full Idea: If objects are reducible to atoms, and each thing passes in an atomic time with its own first atom into an atomic point of space, then all moving things are of equal velocity. | |
| From: Sextus Empiricus (Outlines of Pyrrhonism [c.180], III.77) |
| 1900 | If time and place are infinitely divided, it becomes impossible for movement ever to begin [Sext.Empiricus] |
| Full Idea: If bodies, and the places and times when they are said to move, are divided into infinity, motion will not occur, it being impossible to find anything which will initiate the first movement. | |
| From: Sextus Empiricus (Outlines of Pyrrhonism [c.180], III.76) |
| 1899 | Does the original self-mover push itself from behind, or pull itself from in front? [Sext.Empiricus] |
| Full Idea: Self-movement must move in some particular direction, but if it pushes it will be behind itself, and if it pulls it will be in front of itself. | |
| From: Sextus Empiricus (Outlines of Pyrrhonism [c.180], III.68) | |
| A reaction: This is the same as Aquinas's First Way of proving God's existence. |
| 1903 | If motion and rest are abolished, so is time [Sext.Empiricus] |
| Full Idea: Since time does not seem to subsist without motion or even rest, if motion is abolished, and likewise rest, time is abolished. | |
| From: Sextus Empiricus (Outlines of Pyrrhonism [c.180], III.141) |
| 1904 | Time must be unlimited, but past and present can't be non-existent, and can't be now, so time does not exist [Sext.Empiricus] |
| Full Idea: There can't be a time when there was no time, so time is not limited; but unlimited time means past and present are non-existent (so time is limited to the present), or they exist (which means they are present). Time does not exist. | |
| From: Sextus Empiricus (Outlines of Pyrrhonism [c.180], III.142) |
| 1905 | How can time be divisible if we can't compare one length of time with another? [Sext.Empiricus] |
| Full Idea: Time is clearly divisible (into past, present and future), but it can't be, because a divisible thing is measured by some part of itself (divisions of length), but the two parts must coincide to make the measurement (e.g. present must coincide with past). | |
| From: Sextus Empiricus (Outlines of Pyrrhonism [c.180], III.143) |
| 1891 | How can we agree on the concept of God, unless we agree on his substance or form or place? [Sext.Empiricus] |
| Full Idea: How shall we be able to reach a conception of God when we have no agreement about his substance or his form or his place of abode? | |
| From: Sextus Empiricus (Outlines of Pyrrhonism [c.180], III.3) |
| 1892 | The existence of God can't be self-evident or everyone would have agreed on it, so it needs demonstration [Sext.Empiricus] |
| Full Idea: The existence of God is not pre-evident, for if it was the dogmatists would have agreed about it, whereas their disagreements show it is non-evident, and in need of demonstration. | |
| From: Sextus Empiricus (Outlines of Pyrrhonism [c.180], III.6) |
| 1893 | If God foresaw evil he would presumably prevent it, and if he only foresees some things, why those things? [Sext.Empiricus] |
| Full Idea: If God had forethought for all, there would be no evil in the world, yet they say the world is full of evil. And if he forethinks some things, why those and not others? | |
| From: Sextus Empiricus (Outlines of Pyrrhonism [c.180], III.9) |