32 ideas
| 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. |
| 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. |
| 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? |
| 18671 | The ground for an attitude is not a thing's 'goodness', but its concrete characteristics [Ewing] |
| Full Idea: The ground for an attitude lies not in some other ethical concept, goodness, but in the concrete, factual characteristics of what we pronounce good. ...We shall not be better off if we interpolate an indefinable characteristic of goodness besides. | |
| From: A.C. Ewing (The Definition of Good [1948], p.172), quoted by Francesco Orsi - Value Theory 1.4 | |
| A reaction: This is a forerunner of Scanlon's Buck-Passing theory of the source of value (in other properties). I approve of this approach. If I say 'actually this very strong cheese is really good', I'm not adding goodness to the cheese. |
| 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. |
| 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. |
| 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. |
| 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. |
| 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. |
| 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). |
| 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. |