54 ideas
| 23000 | Vicious regresses force you to another level; non-vicious imply another level [Baron/Miller] |
| Full Idea: A regress is vicious if the problem at level n can only be solved at level n+1; it is non-vicious if it can be solved at n, but the solution forces another level n+1, where the problem can be reformulated. | |
| From: Baron,S/Miller,K (Intro to the Philosophy of Time [2019], 2.3.2) | |
| A reaction: So in a vicious regress you chase the apparent solution, but never attain it. In the non-vicious you solve it, but then find you have a new problem. I think. |
| 18806 | Frege thought traditional categories had psychological and linguistic impurities [Frege, by Rumfitt] |
| Full Idea: Frege rejected the traditional categories as importing psychological and linguistic impurities into logic. | |
| From: report of Gottlob Frege (Function and Concept [1891]) by Ian Rumfitt - The Boundary Stones of Thought 1.2 | |
| A reaction: Resisting such impurities is the main motivation for making logic entirely symbolic, but it doesn't follow that the traditional categories have to be dropped. |
| 20100 | Classical liberalism seeks freedom of opinion, of private life, of expression, and of property [Micklethwait/Wooldridge] |
| Full Idea: The classical liberals agreed on a basic list of freedoms: of opinion (including religion), of private life, of expression, and of property | |
| From: Micklethwait,J/Wooldridge,A (The Fourth Revolution [2014], 9) | |
| A reaction: Mill is main articulator of this. Modern neo-liberals focus on economic freedom. Neither of them seem to make freedom of opportunity central, though I suspect our modern Liberal Party would. |
| 8490 | First-level functions have objects as arguments; second-level functions take functions as arguments [Frege] |
| Full Idea: Just as functions are fundamentally different from objects, so also functions whose arguments are and must be functions are fundamentally different from functions whose arguments are objects. The latter are first-level, the former second-level, functions. | |
| From: Gottlob Frege (Function and Concept [1891], p.38) | |
| A reaction: In 1884 he called it 'second-order'. This is the standard distinction between first- and second-order logic. The first quantifies over objects, the second over intensional entities such as properties and propositions. |
| 8492 | Relations are functions with two arguments [Frege] |
| Full Idea: Functions of one argument are concepts; functions of two arguments are relations. | |
| From: Gottlob Frege (Function and Concept [1891], p.39) | |
| A reaction: Nowadays we would say 'two or more'. Another interesting move in the aim of analytic philosophy to reduce the puzzling features of the world to mathematical logic. There is, of course, rather more to some relations than being two-argument functions. |
| 23024 | A traveller takes a copy of a picture into the past, gives it the artist, who then creates the original! [Baron/Miller] |
| Full Idea: Suppose an art critic travels back in time with a copy of an artist's masterpiece, gives the artist the copy, and the artist copies it. The copy of the copy turns out to be the original mastepiece. The artwork seems to come from nowhere. | |
| From: Baron,S/Miller,K (Intro to the Philosophy of Time [2019], 8.6) | |
| A reaction: Lovely thought. Is the example possible (even with time travel)? How would the critic possess the copy before making the time journey? What if the critic decided not to travel back in time? Can a picture exist if no one has imagined it first? |
| 8487 | Arithmetic is a development of logic, so arithmetical symbolism must expand into logical symbolism [Frege] |
| Full Idea: I am of the opinion that arithmetic is a further development of logic, which leads to the requirement that the symbolic language of arithmetic must be expanded into a logical symbolism. | |
| From: Gottlob Frege (Function and Concept [1891], p.30) | |
| A reaction: This may the the one key idea at the heart of modern analytic philosophy (even though logicism may be a total mistake!). Logic and arithmetical foundations become the master of ontology, instead of the servant. The jury is out on the whole enterprise. |
| 18899 | Frege takes the existence of horses to be part of their concept [Frege, by Sommers] |
| Full Idea: Frege regarded the existence of horses as a property of the concept 'horse'. | |
| From: report of Gottlob Frege (Function and Concept [1891]) by Fred Sommers - Intellectual Autobiography 'Realism' |
| 23008 | Grounding is intended as a relation that fits dependences between things [Baron/Miller] |
| Full Idea: Grounding is a posit introduced by metaphysicians in an attempt to devise a relation that can accommodate dependence between things in the world. | |
| From: Baron,S/Miller,K (Intro to the Philosophy of Time [2019], 5.6) | |
| A reaction: Grounding is a recent concept which seems to have lots of enemies, but I assume you can only reject it if you reject the concept of dependence - yet that seems a fairly obvious fact to me. My favoured metaphysical relation is 'determination'. |
| 4028 | Frege allows either too few properties (as extensions) or too many (as predicates) [Mellor/Oliver on Frege] |
| Full Idea: Frege's theory of properties (which he calls 'concepts') yields too few properties, by identifying coextensive properties, and also too many, by letting every predicate express a property. | |
| From: comment on Gottlob Frege (Function and Concept [1891]) by DH Mellor / A Oliver - Introduction to 'Properties' §2 | |
| A reaction: Seems right; one extension may have two properties (have heart/kidneys), two predicates might express the same property. 'Cutting nature at the joints' covers properties as well as objects. |
| 8489 | The concept 'object' is too simple for analysis; unlike a function, it is an expression with no empty place [Frege] |
| Full Idea: I regard a regular definition of 'object' as impossible, since it is too simple to admit of logical analysis. Briefly: an object is anything that is not a function, so that an expression for it does not contain any empty place. | |
| From: Gottlob Frege (Function and Concept [1891], p.32) | |
| A reaction: Here is the core of the programme for deriving our ontology from our logic and language, followed through by Russell and Quine. Once we extend objects beyond the physical, it becomes incredibly hard to individuate them. |
| 23018 | How does a changing object retain identity or have incompatible properties over time? [Baron/Miller] |
| Full Idea: The problems of temporary intrinsics are reconciling the indiscernibility of identicals with change in an object over time, and the problem of something have incompatible properties over time (such as tired and not-tired). | |
| From: Baron,S/Miller,K (Intro to the Philosophy of Time [2019], 7.3.1) | |
| A reaction: Loosely speaking, I would offer some sort of essentialism as the answer to these problems. People are not essentially sitting down, or tired. Or we can relativise properties to times t1 and t2. |
| 9947 | Concepts are the ontological counterparts of predicative expressions [Frege, by George/Velleman] |
| Full Idea: Concepts, for Frege, are the ontological counterparts of predicative expressions. | |
| From: report of Gottlob Frege (Function and Concept [1891]) by A.George / D.J.Velleman - Philosophies of Mathematics Ch.2 | |
| A reaction: That sounds awfully like what many philosophers call 'universals'. Frege, as a platonist (at least about numbers), I would take to be in sympathy with that. At least we can say that concepts seem to be properties. |
| 10319 | An assertion about the concept 'horse' must indirectly speak of an object [Frege, by Hale] |
| Full Idea: Frege had a notorious difficulty over the concept 'horse', when he suggests that if we wish to assert something about a concept, we are obliged to proceed indirectly by speaking of an object that represents it. | |
| From: report of Gottlob Frege (Function and Concept [1891], Ch.2.II) by Bob Hale - Abstract Objects | |
| A reaction: This sounds like the thin end of a wedge. The great champion of objects is forced to accept them here as a façon de parler, when elsewhere they have ontological status. |
| 8488 | A concept is a function whose value is always a truth-value [Frege] |
| Full Idea: A concept in logic is closely connected with what we call a function. Indeed, we may say at once: a concept is a function whose value is always a truth-value. ..I give the name 'function' to what is meant by the 'unsaturated' part. | |
| From: Gottlob Frege (Function and Concept [1891], p.30) | |
| A reaction: So a function becomes a concept when the variable takes a value. Problems arise when the value is vague, or the truth-value is indeterminable. |
| 9948 | Unlike objects, concepts are inherently incomplete [Frege, by George/Velleman] |
| Full Idea: For Frege, concepts differ from objects in being inherently incomplete in nature. | |
| From: report of Gottlob Frege (Function and Concept [1891]) by A.George / D.J.Velleman - Philosophies of Mathematics Ch.2 | |
| A reaction: This is because they are 'unsaturated', needing a quantified variable to complete the sentence. This could be a pointer towards Quine's view of properties, as simply an intrinsic feature of predication about objects, with no separate identity. |
| 4972 | I may regard a thought about Phosphorus as true, and the same thought about Hesperus as false [Frege] |
| Full Idea: From sameness of meaning there does not follow sameness of thought expressed. A fact about the Morning Star may express something different from a fact about the Evening Star, as someone may regard one as true and the other false. | |
| From: Gottlob Frege (Function and Concept [1891], p.14) | |
| A reaction: This all gets clearer if we distinguish internalist and externalist theories of content. Why take sides on this? Why not just ask 'what is in the speaker's head?', 'what does the sentence mean in the community?', and 'what is the corresponding situation?' |
| 20097 | The welfare state aims at freedom from want, and equality of opportunity [Micklethwait/Wooldridge] |
| Full Idea: In the classical liberal tradition freedom meant freedom from external control, and equality meant equality before the law. In the welfare state (of Beatrice Webb) freedom was reinterpreted as freedom from want, and equality as equality of opportunity. | |
| From: Micklethwait,J/Wooldridge,A (The Fourth Revolution [2014], 3) | |
| A reaction: The authors call this the 'third revolution' in government, after 17th century centralisation and early 19th century accountability. Tawney 1931 is the key text. |
| 20099 | For communists history is driven by the proletariat [Micklethwait/Wooldridge] |
| Full Idea: For the communists the proletariat rather than the state was the locomotive of history. | |
| From: Micklethwait,J/Wooldridge,A (The Fourth Revolution [2014], 3) | |
| A reaction: I feel increasingly reluctant to support any party which appears to mainly represent the interests of a single social class, no matter how large that class may be. An attraction of liberalism is that it makes no reference to class. |
| 20098 | Fans of economic freedom claim that capitalism is self-correcting [Micklethwait/Wooldridge] |
| Full Idea: The central laissez-faire conceit is that capitalism is a self-correcting mechanism. | |
| From: Micklethwait,J/Wooldridge,A (The Fourth Revolution [2014], 3) | |
| A reaction: This was Keynes's rather left-wing criticism of standard capitalist views. These resurfaced in the 1980s with mantras about the virtues of 'market forces'. |
| 20096 | Roman law entrenched property rights [Micklethwait/Wooldridge] |
| Full Idea: Roman law entrenched property rights. | |
| From: Micklethwait,J/Wooldridge,A (The Fourth Revolution [2014], 1 Intro) | |
| A reaction: Normally attributed to Locke, so this is a good corrective. Was the principle gradually forgotten before Locke? |
| 23011 | Modern accounts of causation involve either processes or counterfactuals [Baron/Miller] |
| Full Idea: The two major contemporary theories of causation are process theories and counterfactual theories. …Process theories treat it as something to be discovered. …Counterfactual theories ignore processes, and treat it in terms of truth and falsity. | |
| From: Baron,S/Miller,K (Intro to the Philosophy of Time [2019], 6.1) | |
| A reaction: I take the counterfactual theory to be a specialised branch of the project of analytic metaphysics, which seeks the logical form of causation sentences, using possible worlds semantics. In the real word its processes or nothing. |
| 23013 | The main process theory of causation says it is transference of mass, energy, momentum or charge [Baron/Miller] |
| Full Idea: According to contemporary process theories of causation it consists of the transference of a 'mark', which is always some conserved quantity. Candidates (from science) are mass, energy, momentum and electric charge. | |
| From: Baron,S/Miller,K (Intro to the Philosophy of Time [2019], 6.2.2) | |
| A reaction: Given my commitment to physicalism, this is my preferred theory of causation. It began with the suggestion of energy-transfer, but has broadened into the present idea. It is an updated version of the Newton view, as the meeting of objects. |
| 23014 | If causes are processes, what is causation by omission? (Distinguish legal from scientific causes?) [Baron/Miller] |
| Full Idea: Process theories of causation face a serious problem, such as killing a plant by failing to water it - a cause by omission. …Defenders of the theory propose two concepts of causation: one for legal and one for scientific contexts. | |
| From: Baron,S/Miller,K (Intro to the Philosophy of Time [2019], 6.2.3) | |
| A reaction: Not much of a problem, I think. Clearly the scientific concept has priority. The plant died of dehydration, resulting from the consumption and evaporation of the available water. The human causes of that situation are legion. |
| 23015 | The counterfactual theory of causation handles the problem no matter what causes actually are [Baron/Miller] |
| Full Idea: The chief advantage of the counterfactual theory of causation is that it is flexible enough to handle causation no matter what in the world underlies the causal facts in question. | |
| From: Baron,S/Miller,K (Intro to the Philosophy of Time [2019], 6.3) | |
| A reaction: It has this advantage because it makes no attempt to explain causation, but merely gives an accurate map of the truth and falsity of causal statements. It describes how we think about causation. |
| 23016 | Counterfactual theories struggle with pre-emption by a causal back-up system [Baron/Miller] |
| Full Idea: Counterfactual theories of causation have difficulty accommodating pre-emption, which involves the existence of causal back-up systems that undermine counterfactual dependence. | |
| From: Baron,S/Miller,K (Intro to the Philosophy of Time [2019], 6.5) | |
| A reaction: E.g. If your stone hadn't broken the window first, my stone would have broken it instead. So in the nearest world the withholding of your stone doesn't save the window. |
| 23009 | There is no second 'law' of thermodynamics; it just reflects probabilities of certain microstates [Baron/Miller] |
| Full Idea: According to contemporary statistical mechanics the second law of thermodynamics is not really a law at all, but merely reflects to probabilities of certain microstates, conditional on local boundary conditions having certain properties. | |
| From: Baron,S/Miller,K (Intro to the Philosophy of Time [2019], 5.6.1) | |
| A reaction: A nice illustration of how metaphysicians have been seduced by the 'laws' of nature into falsely inferring all sorts of natural necessities. Entropy is normally assumed to be totally inevitable, because of some natural force. It's just a pattern. |
| 23002 | In relativity space and time depend on one's motion, but spacetime gives an invariant metric [Baron/Miller] |
| Full Idea: While spatial and temporal distances in relativity depend on one's relative state of motion, spatiotemporal distances within Minkowski spacetime do not. It therefore provides an invariant metric for describing the distances between things. | |
| From: Baron,S/Miller,K (Intro to the Philosophy of Time [2019], 4.2) | |
| A reaction: I doubt whether this solves all the worries which philosophers have, about relativity giving an account of time which contradicts our concept of time in every other area of our understanding. |
| 22988 | The block universe theory says entities of all times exist, and time is the B-series [Baron/Miller] |
| Full Idea: The standard block universe theory combines EntityEverywhenism with the B-theory of time. | |
| From: Baron,S/Miller,K (Intro to the Philosophy of Time [2019], 1.4) | |
| A reaction: This is also known as 'eternalism'. These authors emphasise that there is an ontological commitment to the objects of past and future in eternalism, as well as the B-series view of the moments of time. |
| 22991 | How can we know this is the present moment, if other times are real? [Baron/Miller] |
| Full Idea: According to the spotlight and growing block views, there is a single objectively present moment, and also other objectively existing moments. But then how do persons in those different moments know which one is present? | |
| From: Baron,S/Miller,K (Intro to the Philosophy of Time [2019], 1.6) | |
| A reaction: [compressed example] This sceptical thought leads either towards Presentism (we know we are present because that's all there is), or Eternalism (there is no present moment, so no problem). A good objection to spotlight and growing block. |
| 22992 | If we are actually in the past then we shouldn't experience time passing [Baron/Miller] |
| Full Idea: If the past really exists, and we are in it, rather than in the present, then we should rationally conclude that we are not experiencing the passage of time. …But then we have no basis for arguing that time is dynamic. | |
| From: Baron,S/Miller,K (Intro to the Philosophy of Time [2019], 1.6) | |
| A reaction: [compressed] It is certainly difficult to conceive how past times and entities could be real in every way, except that the experience of time passing has been removed. But if past people experience passing, they must believe they are present… |
| 22994 | Erzatz Presentism allows the existence of other times, with only the present 'actualised' [Baron/Miller] |
| Full Idea: The 'erzatz presentism' view is that either the past and present exist, or all times exist, but only the present is 'actualised'. Standard Presentism says no times exist other than the present. | |
| From: Baron,S/Miller,K (Intro to the Philosophy of Time [2019], 1.7.2) | |
| A reaction: Ersatz presentism is obviously a close relative of the moving spotlight and growing block views. No account seems possible of the distinction between 'exists' and 'actualised' (other than the former being a mere abstract concept). |
| 22998 | How do presentists explain relations between things existing at different times? [Baron/Miller] |
| Full Idea: A chief challenge facing presentism is how to give an account of cross-temporal relations, which link things that exist with things that do not. | |
| From: Baron,S/Miller,K (Intro to the Philosophy of Time [2019], 2.2) | |
| A reaction: The problem of whether to keep a dubious death-bed promise is a bit of a puzzle for all of us, whatever our metaphysical view of time. None of us deny the reality of our great-great-grandparents. |
| 23017 | Presentism needs endurantism, because other theories imply most of the object doesn't exist [Baron/Miller] |
| Full Idea: Presentism is more naturally paired with endurantism, since if we pair it with perdurantism or transdurantism we have to say that most of any persisting object does not exist, and while that is not incoherent it is not very attractive. | |
| From: Baron,S/Miller,K (Intro to the Philosophy of Time [2019], 7.2.2) | |
| A reaction: (I think perdurance is time slices, and transdurance is the complete time worm). My preferred combination is this one: all that exists is the complete objects at the present moment. It also needs strong commitment to the truth of tensed verbs. |
| 23023 | How can presentists move to the next future moment, if that doesn't exist? [Baron/Miller] |
| Full Idea: If Presentism is true, how do we manage to travel from this moment to the next moment, a moment that is, at present, a future and hence non-existent moment? | |
| From: Baron,S/Miller,K (Intro to the Philosophy of Time [2019], 8.3.1) | |
| A reaction: The reply would have to be that the metaphor of 'travel' is inappropriate for the movement through time. Travel needs a succession of existing places. The advancement of time is nothing like that. Nice question, though. |
| 22995 | Most of the sciences depend on the concept of time [Baron/Miller] |
| Full Idea: Without time it is hard to make sense of historical research, evolutionary biology, psychology, chemistry, biology, cosmology, social science, archaeology, practical reason, evidence, human agency and causation. | |
| From: Baron,S/Miller,K (Intro to the Philosophy of Time [2019], 1.8) | |
| A reaction: [compressed] I do find it extraordinary that relativistic physicists cheerfully embrace an eternalist theory of time which seems to render nearly all of the other sciences meaningless. |
| 22993 | For abstractionists past times might still exist, althought their objects don't [Baron/Miller] |
| Full Idea: If past moments are seen as abstract (rather than concrete) it doesn't follow that because past objects no longer exist that therefore past times do not exist. The abstractionist needs to say which times are concretely realised. | |
| From: Baron,S/Miller,K (Intro to the Philosophy of Time [2019], 1.7.2) | |
| A reaction: Abstractionists see times as representations of change, rather than as substances. |
| 23001 | The error theory of time's passage says it is either a misdescription or a false inference [Baron/Miller] |
| Full Idea: According to the cognitive error theory of the passage of time, …it is either our misdescription of our temporal phenomenology, or some mechanism of our brain infers that the phenomenology is caused by time actually passing. | |
| From: Baron,S/Miller,K (Intro to the Philosophy of Time [2019], 3.3.1) | |
| A reaction: [compressed] I think I have some sympathy with the misdescription view. If you imaginatively gradually remove all the changing events in your experience, that doesn't end with a raw experience of pure time, because there is no such thing. |
| 22999 | It is meaningless to measure the rate of time using time itself, and without a rate there is no flow [Baron/Miller] |
| Full Idea: It seems we are forced to measure the rate of time's passing against itself. But that's just not a meaningful rate. So time has no rate. So it doesn't flow. So there is no such thing as temporal passage. | |
| From: Baron,S/Miller,K (Intro to the Philosophy of Time [2019], 2.3.1) | |
| A reaction: It is suggested that you can exchange dollars one for one, so time might move at one second per second. But you can't exchange your own dollars with yourself at one-for-one. That is meaningless. Time is NOT a substance which flows. |
| 22986 | The C-series rejects A and B, and just sees times as order by betweenness, without direction [Baron/Miller] |
| Full Idea: The C-series sees times not as directed, but as unchanging, and ordered in terms of the betweenness relation. The C-theory also asserts that the A-series and B-series do not exist. | |
| From: Baron,S/Miller,K (Intro to the Philosophy of Time [2019], 1.2) | |
| A reaction: This is McTaggart's idea. Compare this with A-series ordering by past, present and future, and B-series ordering by earlier-than, later-than and simultaneous. The main point is that A and B have a direction, but C does not. |
| 22996 | The A-series has to treat being past, present or future as properties [Baron/Miller] |
| Full Idea: One of the limitations of the A-series is that temporal passage then presupposes the existence of properties of being present, being past and being future. | |
| From: Baron,S/Miller,K (Intro to the Philosophy of Time [2019], 2.1) | |
| A reaction: Metaphysicians happily talk about 'properties' all the time, and most of them never grasp how ambiguous and obscure that concept is. The idea that my recent scratching of my chin first acquired the 'present' property and then lost it is incoherent. |
| 23007 | The B-series can have a direction, as long as it does not arise from temporal flow [Baron/Miller] |
| Full Idea: The view that time has a direction is entirely consistent with the B-theory of time, as long as time's having a direction is not a matter of it having temporal flow. | |
| From: Baron,S/Miller,K (Intro to the Philosophy of Time [2019], 5.5) | |
| A reaction: I'm not sure how you could account for an intrinsic direction to time if it is not because of the 'flow'. The B-series seems to invite a reductive account of time's direction (e.g. to entropy). |
| 23003 | Static theories cannot account for time's obvious asymmetry, so time must be dynamic [Baron/Miller] |
| Full Idea: One argument for the dynamic theory of time is that time is, obviously, asymmetric, and as static theories can't account for this asymmetry, we ought to posit temporal passage to explain it. | |
| From: Baron,S/Miller,K (Intro to the Philosophy of Time [2019], 5) | |
| A reaction: The B-series view (unlike the C-series) asserts that there is an order from past to future, but it offers no explanation of that fact. Physicists love to tell you the order could be in either direction, But why an 'order' at all? |
| 23004 | The direction of time is either primitive, or reducible to something else [Baron/Miller] |
| Full Idea: Primitivism is the view that time has a direction, and that its having that direction is intrinsic to time itself. Reductionism is the view that time has a direction, but its having that direction is reducible to something else. | |
| From: Baron,S/Miller,K (Intro to the Philosophy of Time [2019], 5.3.1) | |
| A reaction: The general suggestion for the second theory is that time's direction reduces to some aspect of the laws of nature. I strongly incline to the primitive view. Something's got to be primitive. |
| 23005 | The kaon does not seem to be time-reversal invariant, unlike the rest of nature [Baron/Miller] |
| Full Idea: The laws of nature are time-reversal invariant, with the small exception of the kaon (a type of sub-atomic particle) | |
| From: Baron,S/Miller,K (Intro to the Philosophy of Time [2019], 5.3.2) | |
| A reaction: If that fact about the kaon were very secure indeed, then that would mean the collapse of the claims about the time-invariance of the laws. Since time-invariance is still routinely asserted, I assume it is not secure. |
| 23006 | Maybe the past is just the direction of decreasing entropy [Baron/Miller] |
| Full Idea: We could say that what we call the past is just the direction towards (for instance) decreasing entropy, and the direction we call the future is the direction towards increasing entropy. | |
| From: Baron,S/Miller,K (Intro to the Philosophy of Time [2019], 5.3.3) | |
| A reaction: One problem is that locally entropy can sometimes go the other way, which would imply local pockets with a reversed time's arrow,. |
| 23010 | We could explain time's direction by causation: past is the direction of causes, future of effects [Baron/Miller] |
| Full Idea: An option for accounting for the direction of time would be to appeal to the direction of causation …to the future is the direction towards which there are effects, and the past is the direction towards which there are causes. | |
| From: Baron,S/Miller,K (Intro to the Philosophy of Time [2019], 5.6.2) | |
| A reaction: The obvious problem is that we can no longer pick out a cause by saying it 'precedes' its effect. It is not obvious what other criterion can be used to distinguish them (esp. given Hume's regularity account). |
| 22989 | Static time theory presents change as one property at t1, and a different property at t2 [Baron/Miller] |
| Full Idea: The static theory of time appeals to an 'at-at' notion of change, which analyses change as objects or events having one property at time t1, and a different property at t2. (The worry about this is that it describes variation, but not real change). | |
| From: Baron,S/Miller,K (Intro to the Philosophy of Time [2019], 1.4) | |
| A reaction: I suppose observing a different property at t2 is observing the result of a change, rather than the process. But then the process might be broken down into micro-gradations of properties. Maybe only results can be observed. |
| 23020 | If a time traveller kills his youthful grandfather, he both exists and fails to exist [Baron/Miller] |
| Full Idea: It is surely true that if a time traveller travels back in time and succeeds in shooting his youthful grandfather then the time traveller both exists and fails to exist. | |
| From: Baron,S/Miller,K (Intro to the Philosophy of Time [2019], 8.2) | |
| A reaction: This is the best known paradox of time travel. It is a special dramatic case of making any change to the past. If the traveller kills his neighbour's grandfather, his neighbour should vanish. Moving a speck of dust could have enduring results. |
| 23022 | Presentism means there no existing past for a time traveller to visit [Baron/Miller] |
| Full Idea: A time traveller can only travel to a location if the location exists, But if Presentism is true then past locations do not exist, so time travel to the past is impossible. | |
| From: Baron,S/Miller,K (Intro to the Philosophy of Time [2019], 8.3.1) | |
| A reaction: Might a time machine actually restore the past time which had ceased to exist? Then the problem is the information needed to achieve that. |
| 22987 | The past (unlike the future) is fixed, along with truths about it, by the existence of past objects [Baron/Miller] |
| Full Idea: It is the existence of past objects that explains why the past is fixed, and why there are truths about the past, and it is the non-existence of future objects that explains why the future is malleable. | |
| From: Baron,S/Miller,K (Intro to the Philosophy of Time [2019], 1.3) | |
| A reaction: The authors label this view 'EntityNowandThenism', and it comes in a section on the 'Temporal Ontology'. |
| 22990 | The moving spotlight says entities can have properties of being present, past or future [Baron/Miller] |
| Full Idea: The moving spotlight theorist maintains that there are special temporal properties that entities possess, namely the properties of being present, being past and being future. | |
| From: Baron,S/Miller,K (Intro to the Philosophy of Time [2019], 1.5.3) | |
| A reaction: Are these thought to be intrinsic properties of the objects, or (more plausibly) relational properties, between objects and times? Either view is weird. Does some godlike part of time scurry along, illuminating things, like a mouse under a carpet? |
| 22997 | The present moment is a matter of existence, not of acquiring a property [Baron/Miller] |
| Full Idea: Rather than treating presentness as an acquired property …. presentism equates the metaphysical specialness of the present with existence. | |
| From: Baron,S/Miller,K (Intro to the Philosophy of Time [2019], 2.2) | |
| A reaction: It seems like common sense to say that the recent scratching of my chin came into existence and then went out of existence (rather than that it acquired and then lost a property). |
| 8491 | The Ontological Argument fallaciously treats existence as a first-level concept [Frege] |
| Full Idea: The ontological proof of God's existence suffers from the fallacy of treating existence as a first-level concept. | |
| From: Gottlob Frege (Function and Concept [1891], p.38 n) | |
| A reaction: [See Idea 8490 for first- and second-order functions] This is usually summarised as the idea that existence is a quantifier rather than a predicate. |