65 ideas
| 12274 | Begin examination with basics, and subdivide till you can go no further [Aristotle] |
| Full Idea: The examination must be carried on and begin from the primary classes and then go on step by step until further division is impossible. | |
| From: Aristotle (Topics [c.331 BCE], 109b17) | |
| A reaction: This is a good slogan for the analytic approach to thought. I take Aristotle (or possibly Socrates) to be the father of analysis, not Frege (though see Idea 9840). (He may be thinking of the tableau method of proof). |
| 12260 | Dialectic starts from generally accepted opinions [Aristotle] |
| Full Idea: Reasoning is dialectical which reasons from generally accepted opinions. | |
| From: Aristotle (Topics [c.331 BCE], 100a30) | |
| A reaction: This is right at the heart of Aristotle's philosophical method, and Greek thinking generally. There are nice modern debates about 'folk' understanding, derived from science (e.g. quantum theory) which suggest that starting from normal views is a bad idea. |
| 12291 | There can't be one definition of two things, or two definitions of the same thing [Aristotle] |
| Full Idea: There cannot possibly be one definition of two things, or two definitions of the same thing. | |
| From: Aristotle (Topics [c.331 BCE], 154a11) | |
| A reaction: The second half of this is much bolder and more controversial, and plenty of modern thinkers would flatly reject it. Are definitions contextual, that is, designed for some specific human purpose. Must definitions be of causes? |
| 12292 | Definitions are easily destroyed, since they can contain very many assertions [Aristotle] |
| Full Idea: A definition is the easiest of all things to destroy; for, since it contains many assertions, the opportunities which it offers are very numerous, and the more abundant the material, the more quickly the reasoning can set to work. | |
| From: Aristotle (Topics [c.331 BCE], 155a03) | |
| A reaction: I quote this to show that Aristotle expected many definitions to be very long affairs (maybe even of book length?) |
| 12261 | Differentia are generic, and belong with genus [Aristotle] |
| Full Idea: The differentia, being generic in character, should be ranged with the genus. | |
| From: Aristotle (Topics [c.331 BCE], 101b18) | |
| A reaction: This does not mean that naming the differentia amounts to mere classification. I presume we can only state individual differences by using a language which is crammed full of universals. |
| 12263 | 'Genus' is part of the essence shared among several things [Aristotle] |
| Full Idea: A 'genus' is that which is predicated in the category of essence of several things which differ in kind. | |
| From: Aristotle (Topics [c.331 BCE], 102a32) | |
| A reaction: Hence a genus is likely to be expressed by a universal, a one-over-many. A particular will be a highly individual collection of various genera, but what ensures the uniqueness of each thing, if they are indiscernible? |
| 12272 | We describe the essence of a particular thing by means of its differentiae [Aristotle] |
| Full Idea: We usually isolate the appropriate description of the essence of a particular thing by means of the differentiae which are peculiar to it. | |
| From: Aristotle (Topics [c.331 BCE], 108b05) | |
| A reaction: I take this to be important for showing the definition is more than mere categorisation. A good definition homes in the particular, by gradually narrowing down the differentiae. |
| 12279 | The differentia indicate the qualities, but not the essence [Aristotle] |
| Full Idea: No differentia indicates the essence [ti estin], but rather some quality, such as 'pedestrian' or 'biped'. | |
| From: Aristotle (Topics [c.331 BCE], 122b17) | |
| A reaction: We must disentangle this, since essence is what is definable, and definition seems to give us the essence, and yet it appears that definition only requires genus and differentia. Differentiae seem to be both generic and fine-grained. See Idea 12280! |
| 12283 | In definitions the first term to be assigned ought to be the genus [Aristotle] |
| Full Idea: In definitions the first term to be assigned ought to be the genus. | |
| From: Aristotle (Topics [c.331 BCE], 132a12) | |
| A reaction: We mustn't be deluded into thinking that nothing else is required. I take the increasing refinement of differentiae to be where the real action is. The genus gives you 70% of the explanation. |
| 12289 | The genera and the differentiae are part of the essence [Aristotle] |
| Full Idea: The genera and the differentiae are predicated in the category of essence. | |
| From: Aristotle (Topics [c.331 BCE], 153a19) | |
| A reaction: The definition is words, and the essence is real, so our best definition might not fully attain to the essence. Aristotle has us reaching out to the world through our definitions. |
| 12285 | The definition is peculiar to one thing, not common to many [Aristotle] |
| Full Idea: The definition ought to be peculiar to one thing, not common to many. | |
| From: Aristotle (Topics [c.331 BCE], 149b24) | |
| A reaction: I take this to be very important, against those who think that definition is no more than mere categorisation. To explain, you must get down to the level of the individual. We must explain that uniquely docile tiger. |
| 11261 | Puzzles arise when reasoning seems equal on both sides [Aristotle] |
| Full Idea: The equality of opposite reasonings is the cause of aporia; for it is when we reason on both [sides of a question] and it appears to us that everything can come about either way, that we are in a state of aporia about which of the two ways to take up. | |
| From: Aristotle (Topics [c.331 BCE], 145b17), quoted by Vassilis Politis - Aristotle and the Metaphysics 3.1 | |
| A reaction: Other philosophers give up on the subject in this situation, but I love Aristotle because he takes this to be the place where philosophy begins. |
| 12273 | Unit is the starting point of number [Aristotle] |
| Full Idea: They say that the unit [monada] is the starting point of number (and the point the starting-point of a line). | |
| From: Aristotle (Topics [c.331 BCE], 108b30) | |
| A reaction: Yes, despite Frege's objections in the early part of the 'Grundlagen' (1884). I take arithmetic to be rooted in counting, despite all abstract definitions of number by Frege and Dedekind. Identity gives the unit, which is countable. See also Topics 141b9 |
| 22919 | A thing which makes no difference seems unlikely to exist [Le Poidevin] |
| Full Idea: It is a powerful argument for something's non-existence that it would make absolutely no difference. | |
| From: Robin Le Poidevin (Travels in Four Dimensions [2003], 02 'Everything') | |
| A reaction: Powerful, but not conclusive. Neutrinos don't seem to do much, so it isn't far from there to get a particle which does nothing. |
| 12267 | There are ten categories: essence, quantity, quality, relation, place, time, position, state, activity, passivity [Aristotle] |
| Full Idea: The four main types of predicates fall into ten categories: essence, quantity, quality, relation, place, time, position, state, activity, passivity. | |
| From: Aristotle (Topics [c.331 BCE], 103b20) | |
| A reaction: These are the standard ten categories of Aristotle. He is notable for the divisions not being sharp, and ten being a rough total. He is well aware of the limits of precision in such matters. |
| 12282 | An individual property has to exist (in past, present or future) [Aristotle] |
| Full Idea: If it does not at present exist, or, if it has not existed in the past, or if it is not going to exist in the future, it will not be a property [idion] at all. | |
| From: Aristotle (Topics [c.331 BCE], 129a27) | |
| A reaction: This seems to cramp our style in counterfactual discussion. Can't we even mention an individual property if we believe that it will never exist. Utopian political discussion will have to cease! |
| 12264 | An 'accident' is something which may possibly either belong or not belong to a thing [Aristotle] |
| Full Idea: An 'accident' [sumbebekos] is something which may possibly either belong or not belong to any one and the self-same thing, such as 'sitting posture' or 'whiteness'. This is the best definition, because it tells us the essential meaning of the term itself. | |
| From: Aristotle (Topics [c.331 BCE], 102b07) | |
| A reaction: Thus a car could be red, or not red. Accidents are contingent. It does not follow that necessary properties are essential (see Idea 12262). There are accidents [sumbebekos], propria [idion] and essences [to ti en einai]. |
| 12280 | Genus gives the essence better than the differentiae do [Aristotle] |
| Full Idea: In assigning the essence [ti estin], it is more appropriate to state the genus than the differentiae; for he who describes 'man' as an 'animal' indicates his essence better than he who describes him as 'pedestrian'. | |
| From: Aristotle (Topics [c.331 BCE], 128a24) | |
| A reaction: See Idea 12279. This idea is only part of the story. My reading of this is simply that assigning a genus gives more information. We learn more about him when we say he is a man than when we say he is Socrates. |
| 13269 | In the case of a house the parts can exist without the whole, so parts are not the whole [Aristotle] |
| Full Idea: In the case of a house, where the process of compounding the parts is obvious, though the parts exist, there is no reason why the whole should not be non-existent, and so the parts are not the same as the whole. | |
| From: Aristotle (Topics [c.331 BCE], 150a19) | |
| A reaction: Compare buying a piece of furniture, and being surprised to discover, when it is delivered, that it is self-assembly. This idea is a simple refutation of the claims of classical mereology, that wholes are just some parts. Aristotle uses modal claims. |
| 12284 | Everything that is has one single essence [Aristotle] |
| Full Idea: Everything that is has one single essence [en esti to einai]. | |
| From: Aristotle (Topics [c.331 BCE], 141a36) | |
| A reaction: Does this include vague objects, and abstract 'objects'? Sceptics might ask what grounds this claim. Does Dr Jeckyll have two essences? |
| 12262 | An 'idion' belongs uniquely to a thing, but is not part of its essence [Aristotle] |
| Full Idea: A property [idion] is something which does not show the essence of a thing but belongs to it alone. ...No one calls anything a property which can possibly belong to something else. | |
| From: Aristotle (Topics [c.331 BCE], 102a18) | |
| A reaction: [See Charlotte Witt 106 on this] 'Property' is clearly a bad translation for such an individual item. Witt uses 'proprium', which is a necessary but nonessential property of something. Necessity is NOT the hallmark of essence. See Idea 12266. |
| 12290 | Destruction is dissolution of essence [Aristotle] |
| Full Idea: Destruction is a dissolution of essence. | |
| From: Aristotle (Topics [c.331 BCE], 153b30) | |
| A reaction: [plucked from context!] I can't think of a better way to define destruction, in order to distinguish it from damage. A vase is destroyed when its essential function cannot be recovered. |
| 12286 | If two things are the same, they must have the same source and origin [Aristotle] |
| Full Idea: When things are absolutely the same, their coming-into-being and destruction are also the same and so are the agents of their production and destruction. | |
| From: Aristotle (Topics [c.331 BCE], 152a02) | |
| A reaction: Thus Queen Elizabeth II has to be the result of that particular birth, and from those particular parents, as Kripke says? The inverse may not be true. Do twins have a single origin? Things that fission and then re-fuse differently? etc |
| 12266 | 'Same' is mainly for names or definitions, but also for propria, and for accidents [Aristotle] |
| Full Idea: 'The same' is employed in several senses: its principal sense is for same name or same definition; a second sense occurs when sameness is applied to a property [idiu]; a third sense is applied to an accident. | |
| From: Aristotle (Topics [c.331 BCE], 103a24-33) | |
| A reaction: [compressed] 'Property' is better translated as 'proprium' - a property unique to a particular thing, but not essential - see Idea 12262. Things are made up of essence, propria and accidents, and three ways of being 'the same' are the result. |
| 12287 | Two identical things have the same accidents, they are the same; if the accidents differ, they're different [Aristotle] |
| Full Idea: If two things are the same then any accident of one must also be an accident of the other, and, if one of them is an accident of something else, so must the other be also. For, if there is any discrepancy on these points, obviously they are not the same. | |
| From: Aristotle (Topics [c.331 BCE], 152a36) | |
| A reaction: So what is always called 'Leibniz's Law' should actually be 'Aristotle's Law'! I can't see anything missing from the Aristotle version, but then, since most people think it is pretty obvious, you would expect the great stater of the obvious to get it. |
| 12288 | Numerical sameness and generic sameness are not the same [Aristotle] |
| Full Idea: Things which are the same specifically or generically are not necessarily the same or cannot possibly be the same numerically. | |
| From: Aristotle (Topics [c.331 BCE], 152b32) | |
| A reaction: See also Idea 12266. This looks to me to be a pretty precise anticipation of Peirce's type/token distinction, but without the terminology. It is reassuring that Aristotle spotted it, as that makes it more likely to be a genuine distinction. |
| 12259 | Reasoning is when some results follow necessarily from certain claims [Aristotle] |
| Full Idea: Reasoning [sullogismos] is a discussion in which, certain things having been laid down, something other than these things necessarily results through them. | |
| From: Aristotle (Topics [c.331 BCE], 100a25) | |
| A reaction: This is cited as the standard statement of the nature of logical necessity. One might challenge either the very word 'necessary', or the exact sense of the word employed here. Is it, in fact, metaphysical, or merely analytic? |
| 12271 | Induction is the progress from particulars to universals [Aristotle] |
| Full Idea: Induction is the progress from particulars to universals; if the skilled pilot is the best pilot and the skilled charioteer the best charioteer, then, in general, the skilled man is the best man in any particular sphere. | |
| From: Aristotle (Topics [c.331 BCE], 105a15) | |
| A reaction: It is a bit unclear whether we are deriving universal concepts, or merely general truths. Need general truths be absolute or necessary truths? Presumably occasionally the best person is not the most skilled, as in playing a musical instrument. |
| 12293 | We say 'so in cases of this kind', but how do you decide what is 'of this kind'? [Aristotle] |
| Full Idea: When it is necessary to establish the universal, people use the expression 'So in all cases of this kind'; but it is one of the most difficult tasks to define which of the terms proposed are 'of this kind' and which are not. | |
| From: Aristotle (Topics [c.331 BCE], 157a25) | |
| A reaction: It is particularly hard if induction is expressed as the search for universals, since the kind presumably is the universal, so the universal must be known before the induction can apply, which really is the most frightful nuisance for truth-seekers. |
| 22926 | In addition to causal explanations, they can also be inferential, or definitional, or purposive [Le Poidevin] |
| Full Idea: Not all explanations are causal. We can explain some things by showing what follows logically from what, or what is required by the definition of a term, or in terms of purpose. | |
| From: Robin Le Poidevin (Travels in Four Dimensions [2003], 05 'Limits') | |
| A reaction: Would these fully qualify as 'explanations'? You don't explain the sea by saying that 'wet' is part of its definition. |
| 22932 | We don't just describe a time as 'now' from a private viewpoint, but as a fact about the world [Le Poidevin] |
| Full Idea: In describing a time as 'now' one is not merely describing the world from one's own point of view, but describing the world as it is. | |
| From: Robin Le Poidevin (Travels in Four Dimensions [2003], 08 'Mystery') | |
| A reaction: If we accept this view (which implies absolute time, and the A-series view), then 'now' is not an indexical, in the way that 'I' and 'here' are indexicals. |
| 7903 | The six perfections are giving, morality, patience, vigour, meditation, and wisdom [Nagarjuna] |
| Full Idea: The six perfections are of giving, morality, patience, vigour, meditation, and wisdom. | |
| From: Nagarjuna (Mahaprajnaparamitashastra [c.120], 88) | |
| A reaction: What is 'morality', if giving is not part of it? I like patience and vigour being two of the virtues, which immediately implies an Aristotelian mean (which is always what is 'appropriate'). |
| 12276 | Justice and self-control are better than courage, because they are always useful [Aristotle] |
| Full Idea: Justice [dikaiosune] and self-control [sophrosune] are preferable to courage, for the first two are always useful, but courage only sometimes. | |
| From: Aristotle (Topics [c.331 BCE], 117a36) | |
| A reaction: One could challenge his criterion. What of something which is absolutely vital on occasions, against something which is very mildly useful all the time? You may survive without justice, but not without courage. Compare Idea 12277. |
| 12277 | Friendship is preferable to money, since its excess is preferable [Aristotle] |
| Full Idea: Friendship is preferable to money; for excess of friendship is preferable to excess of money. | |
| From: Aristotle (Topics [c.331 BCE], 118b07) | |
| A reaction: Compare Idea 12276, which gives a different criterion for choosing between virtues. This idea is an interesting qualification of the doctrine of the mean. |
| 12275 | We value friendship just for its own sake [Aristotle] |
| Full Idea: We value friendship for its own sake, even if we are not likely to get anything else from it. | |
| From: Aristotle (Topics [c.331 BCE], 117a03) | |
| A reaction: In 'Ethics' he distinguishes some friendships which don't meet this requirement. Presumably true friendships survive all vicissitudes (except betrayal), but that makes such things fairly rare. |
| 12281 | Man is intrinsically a civilized animal [Aristotle] |
| Full Idea: It is an essential [kath' auto] property of man to be 'by nature a civilized animal'. | |
| From: Aristotle (Topics [c.331 BCE], 128b17) | |
| A reaction: I take this, along with man being intrinsically rational, to be the foundation of Aristotelian ethics. Given that we are civilized, self-evident criteria emerge for how to be good at it. A good person is, above all, a good citizen. |
| 12265 | All water is the same, because of a certain similarity [Aristotle] |
| Full Idea: Any water is said to be specifically the same as any other water because it has a certain similarity to it. | |
| From: Aristotle (Topics [c.331 BCE], 103a20) | |
| A reaction: (Cf. Idea 8153) It take this to be the hallmark of a natural kind, and we should not lose sight of it in the midst of discussions about rigid designation and essential identity. Tigers are only a natural kind insofar as they are indistinguishable. |
| 22927 | The logical properties of causation are asymmetry, transitivity and irreflexivity [Le Poidevin] |
| Full Idea: The usual logical properties of the causal relation are asymmetry (one-way), transitivity and irreflexivity (no self-causing). | |
| From: Robin Le Poidevin (Travels in Four Dimensions [2003], 05 'Great') | |
| A reaction: If two balls rebound off each other, that is only asymmetric if we split the action into two parts, which may be a fiction. Does a bomb cause its own destruction? |
| 22922 | We can identify unoccupied points in space, so they must exist [Le Poidevin] |
| Full Idea: If the midpoint on a line between the chair and the window is five feet from the end of the bookcase. This can be true, but if no object occupies that midpoint, then unoccupied points exist | |
| From: Robin Le Poidevin (Travels in Four Dimensions [2003], 03 'Lessons') | |
| A reaction: We can also locate perfect circles (running through fairy rings, or the rings of Saturn), so they must also exist. But then we can also locate the Loch Ness monster. Hm. |
| 22924 | If spatial points exist, then they must be stationary, by definition [Le Poidevin] |
| Full Idea: If there are such things as points in space, independently of any other object, then these points are by definition stationary (since to be stationary is to stay in the same place, and a point is a place). | |
| From: Robin Le Poidevin (Travels in Four Dimensions [2003], 03 'Search') | |
| A reaction: So what happens if the whole universe moves ten metres to the left? Is the universe defined by the objects in it (which vary), or by the space that contains them? Why can't a location move, even if that is by definition undetectable? |
| 22923 | Absolute space explains actual and potential positions, and geometrical truths [Le Poidevin] |
| Full Idea: Absolutists say space plays a number of roles. It is what we refer to when we talk of positions. It makes other things possible (by moving into unoccupied positions). And it explains geometrical truths. | |
| From: Robin Le Poidevin (Travels in Four Dimensions [2003], 03 'Redundancy') | |
| A reaction: I am persuaded by these, and am happy to treat space (and time) as a primitive of metaphysics. |
| 22928 | For relationists moving an object beyond the edge of space creates new space [Le Poidevin] |
| Full Idea: For the relationist, if Archytas goes to the edge of space and extends his arm, he is creating a new spatial relation between objects, and thus extending space, which is, after all, just the collection of thos relations. | |
| From: Robin Le Poidevin (Travels in Four Dimensions [2003], 05 'beyond') | |
| A reaction: The obvious point is what are you moving your arm into? And how can some movements be in space, while others create new space? It's a bad theory. |
| 22931 | We distinguish time from space, because it passes, and it has a unique present moment [Le Poidevin] |
| Full Idea: The most characteristic features of time, which distinguish it from space, are the fact that time passes, and the fact that the present is in some sense unique | |
| From: Robin Le Poidevin (Travels in Four Dimensions [2003], 08 'Mystery') | |
| A reaction: The B-series view tries to avoid passing time and present moments. I suspect that modern proponents of the B-series mainly want to unifying their view of time with Einstein's, to give us a scientific space-time. |
| 22917 | Since nothing occurs in a temporal vacuum, there is no way to measure its length [Le Poidevin] |
| Full Idea: Since, by definition, nothing happens in a temporal vacuum, there is no possible means of determining its length. | |
| From: Robin Le Poidevin (Travels in Four Dimensions [2003], 02 'without change') | |
| A reaction: This is offered a part of a dubious proof that a temporal vacuum is impossible. I like Shoemaker's three worlds thought experiment, which tests this idea to the limit. |
| 22921 | Temporal vacuums would be unexperienced, unmeasured, and unending [Le Poidevin] |
| Full Idea: Three arguments that a temporal vacuum is impossible: we can't experience it, we can't measure it, and it would have no reason to ever terminate. | |
| From: Robin Le Poidevin (Travels in Four Dimensions [2003], 03 'Lessons') | |
| A reaction: [summarised] The first two reasons are unimpressive. The interiors of black holes are off limits for us. The arrival of time into a timeless situation may actually have occurred, but be beyond our understanding. |
| 22934 | Time can't speed up or slow down, so it doesn't seem to be a 'process' [Le Poidevin] |
| Full Idea: Processes can speed up or slow down, but surely the passage of time is not something that can speed up or slow down? | |
| From: Robin Le Poidevin (Travels in Four Dimensions [2003], 08 'Mystery') | |
| A reaction: If something is a process we can ask 'process of what?', but the only answer seems to be that it's a process of processing. So it is that which makes processes possible (and so, as I keep saying) it is best viewed as a primitive. |
| 22939 | The B-series doesn't seem to allow change [Le Poidevin] |
| Full Idea: How can anything change in a B-universe? | |
| From: Robin Le Poidevin (Travels in Four Dimensions [2003], 08 'Second') | |
| A reaction: It seems that change needs time to move on. A timeless series of varying states doesn't seem to be the same thing as change. B-seriesers must be tempted to deny change, and yet nothing seems more obvious to us than change. |
| 22938 | To say that the past causes the present needs them both to be equally real [Le Poidevin] |
| Full Idea: The causal connection between the past and the present seems to require that the past is as real as the present. | |
| From: Robin Le Poidevin (Travels in Four Dimensions [2003], 08 'First') | |
| A reaction: Cause and effect need to conjoin in space, but their subsequent separation doesn't seem to be a problem. The idea that causes and their effects must be eternally compresent is an absurdity. |
| 22940 | If the B-universe is eternal, why am I trapped in a changing moment of it? [Le Poidevin] |
| Full Idea: What in the B-universe determines my temporal perspective? I can move around in space at will, but I have no choice over where I am in time. What time I am is something that changes, and again I have no control over that | |
| From: Robin Le Poidevin (Travels in Four Dimensions [2003], 08 'Second') | |
| A reaction: The B-series always has to be asserted from the point of view of eternity (e.g. by Einstein). Yet an omniscient mind would still see each of us trapped in our transient moments, so that is part of eternal reality. |
| 22947 | An ordered series can be undirected, but time favours moving from earlier to later [Le Poidevin] |
| Full Idea: A series can be ordered without being directed (such as the series of integers), …but the passage of time indicates a preferred direction, moving from earlier to later events, and never the other way around. | |
| From: Robin Le Poidevin (Travels in Four Dimensions [2003], 12 'Hidden') | |
| A reaction: I wonder what 'preferred' means here? It is not just memory versus anticipation. The saddest words in the English language are 'Too late!'. It is absurd to say that being too late is an illusion. |
| 22952 | If time's arrow is causal, how can there be non-simultaneous events that are causally unconnected? [Le Poidevin] |
| Full Idea: An objection to the Causal analysis of time's arrow is that it is surely possible for non-simultaneous events to be causally unconnected. | |
| From: Robin Le Poidevin (Travels in Four Dimensions [2003], 12 'Seeds') | |
| A reaction: I suppose the events could be linked causally by intermediaries. If reality is a vast causal nexus, everything leads to everything else, in some remote way. It's still a good objections, though. |
| 22953 | Time's arrow is not causal if there is no temporal gap between cause and effect [Le Poidevin] |
| Full Idea: If there is no temporal gap between cause and effect, then the causal analysis of time's arrow is doomed. | |
| From: Robin Le Poidevin (Travels in Four Dimensions [2003], 12 'simultaneous') | |
| A reaction: A number of recent commentators have rejected the sharp distinction between cause and effect, seeing it as a unified process (which takes time to occur). |
| 22951 | If time's arrow is psychological then different minds can impose different orders on events [Le Poidevin] |
| Full Idea: If the Psychological account of time's arrow is correct …then there is nothing to prevent different minds from imposing different orders on the world. | |
| From: Robin Le Poidevin (Travels in Four Dimensions [2003], 12 'The mind's') | |
| A reaction: All we need is for two people to disagree about the order of some past events. The idea that we are psychologically creating time's arrow when everyone feels they are its victims strikes me as a particularly silly theory. |
| 22948 | There are Thermodynamic, Psychological and Causal arrows of time [Le Poidevin] |
| Full Idea: The three most significant arrows of time are the Thermodynamic (the direction from order to disorder), the Psychological (from perceptions of events to memories), and the Causal (from cause to effect). | |
| From: Robin Le Poidevin (Travels in Four Dimensions [2003], 12 'Three') | |
| A reaction: It would be nice if one of these explained the other two. Le Poidevin rejects the Psychological arrow, and seems to favour the Causal. Since I favour taking time as a primitive, I'm inclined to think that the arrow is included in the deal. |
| 22949 | Presumably if time's arrow is thermodynamic then time ends when entropy is complete [Le Poidevin] |
| Full Idea: One consequence of the Thermodynamic analysis of time's arrow is that a universe in which things are as disordered as they could be would exhibit no direction of time at all, because there would be no more significant changes in entropy. | |
| From: Robin Le Poidevin (Travels in Four Dimensions [2003], 12 'Three') | |
| A reaction: And presumably time would gradually fizzle out, rather than ending abruptly. If entropy then went into reverse, there would be no time interval between the end and the new beginning. Entropy can vary locally, so it has to be universal. |
| 22950 | If time is thermodynamic then entropy is necessary - but the theory says it is probable [Le Poidevin] |
| Full Idea: The Second Law of Thermodynamics says it is overwhelmingly probable that entropy will increase. This leaves the door open for occasional isolated instances of decrease. But the thermodynamic arrow makes the increase a necessity. | |
| From: Robin Le Poidevin (Travels in Four Dimensions [2003], 12 'Three') | |
| A reaction: Le Poidevin sees this as a clincher against the thermodynamic explanation of the arrow. I'm now sure how the Second Law can even be stated without explicit or implicit reference to time. |
| 22943 | Instantaneous motion is an intrinsic disposition to be elsewhere [Le Poidevin] |
| Full Idea: Being in motion at a particular time can be an intrinsic property of an object, as a disposition to be elsewhere than the place it is. | |
| From: Robin Le Poidevin (Travels in Four Dimensions [2003], 09 'in present') | |
| A reaction: This needs an ontology which includes unrealised dispositions. People trapped in boring meetings have a disposition to be elsewhere, but they are stuck. I think 'power' is a better word here than 'disposition'. The disposition isn't just for 'elsewhere'. |
| 22945 | The dynamic view of motion says it is primitive, and not reducible to objects, properties and times [Le Poidevin] |
| Full Idea: According to the dynamic account of motion, an object's being in motion is a primitive event, not further analysable in terms of objects, properties and times. | |
| From: Robin Le Poidevin (Travels in Four Dimensions [2003], 09 'Zeno') | |
| A reaction: [The rival view is 'static'] Physics suggests that motion may be indefinable, but acceleration can be given a reductive account. If time and space are taken as primitive (which seems sensible to me), then making motion also primitive is a bit greedy. |
| 22937 | If the present could have diverse pasts, then past truths can't have present truthmakers [Le Poidevin] |
| Full Idea: If any number of pasts are compatible with the present state of affairs, and it is only the present state of affairs which can make true or false statements about the past, then no statement about the past is either true or false. | |
| From: Robin Le Poidevin (Travels in Four Dimensions [2003], 08 'First') | |
| A reaction: He suggests an explosion which could have had innumerable different causes. The explosion could have had different origins, but not sure that the whole of present reality could. Presentists certainly have problems with truthmakers for the past. |
| 22925 | The present is the past/future boundary, so the first moment of time was not present [Le Poidevin] |
| Full Idea: The present is the boundary between past and future, therefore if there was a first moment of time, it could not have been present - because there can be no past at the beginning of time. | |
| From: Robin Le Poidevin (Travels in Four Dimensions [2003], 05 'Limits') | |
| A reaction: How about at the start of a race the athletes cannot be running. How about 'all moments of time have preceding moments - apart from the first moment'? |
| 22944 | The primitive parts of time are intervals, not instants [Le Poidevin] |
| Full Idea: Intervals of time can be viewed as primitive, and not decomposable into a series of instants. | |
| From: Robin Le Poidevin (Travels in Four Dimensions [2003], 09 'in present') | |
| A reaction: Given that instants are nothing, and intervals are something, the latter are clearly the better candidates to be the parts of time. Is there a smallest interval? |
| 22942 | If time is infinitely divisible, then the present must be infinitely short [Le Poidevin] |
| Full Idea: Assuming time to be infinitely divisible, the present can have no duration at all, for if it did, we could divide it into parts, and some parts would be earlier than others. | |
| From: Robin Le Poidevin (Travels in Four Dimensions [2003], 09 'in present') | |
| A reaction: I quite like Aristotle's view that things only have parts when you actually divide them. In modern physics fields don't seem to be infinitely divisible. It's a puzzle, though, innit? |
| 22946 | The multiverse is distinct time-series, as well as spaces [Le Poidevin] |
| Full Idea: The multiverse is not just a collection of distinct spaces, it is also a collection of distinct time-series. | |
| From: Robin Le Poidevin (Travels in Four Dimensions [2003], 11 'Objections') | |
| A reaction: This boggles the imagination even more than distinct spatial universes. |
| 22941 | How could a timeless God know what time it is? So could God be both timeless and omniscient? [Le Poidevin] |
| Full Idea: Could a timeless being now know what the time was? If so, does this show that there must be something wrong with the idea of God as both timeless and omniscient? | |
| From: Robin Le Poidevin (Travels in Four Dimensions [2003], 09 'Questions') | |
| A reaction: This is a potential contradiction between the perfections of a supreme God which I had not noticed before. Leibniz tried to refute such objections, but not very successfully, I think. |
| 12278 | 'Being' and 'oneness' are predicated of everything which exists [Aristotle] |
| Full Idea: 'Being' and 'oneness' are predicated of everything which exists. | |
| From: Aristotle (Topics [c.331 BCE], 121a18) | |
| A reaction: Is 'oneness' predicated of water? So existence always was a predicate, it seems, until Kant told us it wasn't. That existence is a quantifier, not a predicate, seems to be up for question again these days. |