55 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. |
| 21752 | Prior to Gödel we thought truth in mathematics consisted in provability [Gödel, by Quine] |
| Full Idea: Gödel's proof wrought an abrupt turn in the philosophy of mathematics. We had supposed that truth, in mathematics, consisted in provability. | |
| From: report of Kurt Gödel (On Formally Undecidable Propositions [1931]) by Willard Quine - Forward to Gödel's Unpublished | |
| A reaction: This explains the crisis in the early 1930s, which Tarski's theory appeared to solve. |
| 17835 | Gödel show that the incompleteness of set theory was a necessity [Gödel, by Hallett,M] |
| Full Idea: Gödel's incompleteness results of 1931 show that all axiom systems precise enough to satisfy Hilbert's conception are necessarily incomplete. | |
| From: report of Kurt Gödel (On Formally Undecidable Propositions [1931]) by Michael Hallett - Introduction to Zermelo's 1930 paper p.1215 | |
| A reaction: [Hallett italicises 'necessarily'] Hilbert axioms have to be recursive - that is, everything in the system must track back to them. |
| 17886 | The limitations of axiomatisation were revealed by the incompleteness theorems [Gödel, by Koellner] |
| Full Idea: The inherent limitations of the axiomatic method were first brought to light by the incompleteness theorems. | |
| From: report of Kurt Gödel (On Formally Undecidable Propositions [1931]) by Peter Koellner - On the Question of Absolute Undecidability 1.1 |
| 10071 | Second Incompleteness: nice theories can't prove their own consistency [Gödel, by Smith,P] |
| Full Idea: Second Incompleteness Theorem: roughly, nice theories that include enough basic arithmetic can't prove their own consistency. | |
| From: report of Kurt Gödel (On Formally Undecidable Propositions [1931]) by Peter Smith - Intro to Gödel's Theorems 1.5 | |
| A reaction: On the face of it, this sounds less surprising than the First Theorem. Philosophers have often noticed that it seems unlikely that you could use reason to prove reason, as when Descartes just relies on 'clear and distinct ideas'. |
| 19123 | If soundness can't be proved internally, 'reflection principles' can be added to assert soundness [Gödel, by Halbach/Leigh] |
| Full Idea: Gödel showed PA cannot be proved consistent from with PA. But 'reflection principles' can be added, which are axioms partially expressing the soundness of PA, by asserting what is provable. A Global Reflection Principle asserts full soundness. | |
| From: report of Kurt Gödel (On Formally Undecidable Propositions [1931]) by Halbach,V/Leigh,G.E. - Axiomatic Theories of Truth (2013 ver) 1.2 | |
| A reaction: The authors point out that this needs a truth predicate within the language, so disquotational truth won't do, and there is a motivation for an axiomatic theory of truth. |
| 10621 | Gödel's First Theorem sabotages logicism, and the Second sabotages Hilbert's Programme [Smith,P on Gödel] |
| Full Idea: Where Gödel's First Theorem sabotages logicist ambitions, the Second Theorem sabotages Hilbert's Programme. | |
| From: comment on Kurt Gödel (On Formally Undecidable Propositions [1931]) by Peter Smith - Intro to Gödel's Theorems 36 | |
| A reaction: Neo-logicism (Crispin Wright etc.) has a strategy for evading the First Theorem. |
| 17888 | The undecidable sentence can be decided at a 'higher' level in the system [Gödel] |
| Full Idea: My undecidable arithmetical sentence ...is not at all absolutely undecidable; rather, one can always pass to 'higher' systems in which the sentence in question is decidable. | |
| From: Kurt Gödel (On Formally Undecidable Propositions [1931]), quoted by Peter Koellner - On the Question of Absolute Undecidability 1.1 | |
| A reaction: [a 1931 MS] He says the reals are 'higher' than the naturals, and the axioms of set theory are higher still. The addition of a truth predicate is part of what makes the sentence become decidable. |
| 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? |
| 10132 | There can be no single consistent theory from which all mathematical truths can be derived [Gödel, by George/Velleman] |
| Full Idea: Gödel's far-reaching work on the nature of logic and formal systems reveals that there can be no single consistent theory from which all mathematical truths can be derived. | |
| From: report of Kurt Gödel (On Formally Undecidable Propositions [1931]) by A.George / D.J.Velleman - Philosophies of Mathematics Ch.8 |
| 3198 | Gödel showed that arithmetic is either incomplete or inconsistent [Gödel, by Rey] |
| Full Idea: Gödel's theorem states that either arithmetic is incomplete, or it is inconsistent. | |
| From: report of Kurt Gödel (On Formally Undecidable Propositions [1931]) by Georges Rey - Contemporary Philosophy of Mind 8.7 |
| 10072 | First Incompleteness: arithmetic must always be incomplete [Gödel, by Smith,P] |
| Full Idea: First Incompleteness Theorem: any properly axiomatised and consistent theory of basic arithmetic must remain incomplete, whatever our efforts to complete it by throwing further axioms into the mix. | |
| From: report of Kurt Gödel (On Formally Undecidable Propositions [1931]) by Peter Smith - Intro to Gödel's Theorems 1.2 | |
| A reaction: This is because it is always possible to formulate a well-formed sentence which is not provable within the theory. |
| 9590 | Arithmetical truth cannot be fully and formally derived from axioms and inference rules [Gödel, by Nagel/Newman] |
| Full Idea: The vast continent of arithmetical truth cannot be brought into systematic order by laying down a fixed set of axioms and rules of inference from which every true mathematical statement can be formally derived. For some this was a shocking revelation. | |
| From: report of Kurt Gödel (On Formally Undecidable Propositions [1931]) by E Nagel / JR Newman - Gödel's Proof VII.C | |
| A reaction: Good news for philosophy, I'd say. The truth cannot be worked out by mechanical procedures, so it needs the subtle and intuitive intelligence of your proper philosopher (Parmenides is the role model) to actually understand reality. |
| 11069 | Gödel's Second says that semantic consequence outruns provability [Gödel, by Hanna] |
| Full Idea: Gödel's Second Incompleteness Theorem says that true unprovable sentences are clearly semantic consequences of the axioms in the sense that they are necessarily true if the axioms are true. So semantic consequence outruns provability. | |
| From: report of Kurt Gödel (On Formally Undecidable Propositions [1931]) by Robert Hanna - Rationality and Logic 5.3 |
| 10118 | First Incompleteness: a decent consistent system is syntactically incomplete [Gödel, by George/Velleman] |
| Full Idea: First Incompleteness Theorem: If S is a sufficiently powerful formal system, then if S is consistent then S is syntactically incomplete. | |
| From: report of Kurt Gödel (On Formally Undecidable Propositions [1931]) by A.George / D.J.Velleman - Philosophies of Mathematics Ch.6 | |
| A reaction: Gödel found a single sentence, effectively saying 'I am unprovable in S', which is neither provable nor refutable in S. |
| 10122 | Second Incompleteness: a decent consistent system can't prove its own consistency [Gödel, by George/Velleman] |
| Full Idea: Second Incompleteness Theorem: If S is a sufficiently powerful formal system, then if S is consistent then S cannot prove its own consistency | |
| From: report of Kurt Gödel (On Formally Undecidable Propositions [1931]) by A.George / D.J.Velleman - Philosophies of Mathematics Ch.6 | |
| A reaction: This seems much less surprising than the First Theorem (though it derives from it). It was always kind of obvious that you couldn't use reason to prove that reason works (see, for example, the Cartesian Circle). |
| 10611 | There is a sentence which a theory can show is true iff it is unprovable [Gödel, by Smith,P] |
| Full Idea: The original Gödel construction gives us a sentence that a theory shows is true if and only if it satisfies the condition of being unprovable-in-that-theory. | |
| From: report of Kurt Gödel (On Formally Undecidable Propositions [1931]) by Peter Smith - Intro to Gödel's Theorems 20.5 |
| 10867 | 'This system can't prove this statement' makes it unprovable either way [Gödel, by Clegg] |
| Full Idea: An approximation of Gödel's Theorem imagines a statement 'This system of mathematics can't prove this statement true'. If the system proves the statement, then it can't prove it. If the statement can't prove the statement, clearly it still can't prove it. | |
| From: report of Kurt Gödel (On Formally Undecidable Propositions [1931]) by Brian Clegg - Infinity: Quest to Think the Unthinkable Ch.15 | |
| A reaction: Gödel's contribution to this simple idea seems to be a demonstration that formal arithmetic is capable of expressing such a statement. |
| 8747 | Realists are happy with impredicative definitions, which describe entities in terms of other existing entities [Gödel, by Shapiro] |
| Full Idea: Gödel defended impredicative definitions on grounds of ontological realism. From that perspective, an impredicative definition is a description of an existing entity with reference to other existing entities. | |
| From: report of Kurt Gödel (On Formally Undecidable Propositions [1931]) by Stewart Shapiro - Thinking About Mathematics 5.3 | |
| A reaction: This is why constructivists must be absolutely precise about definition, where realists only have to do their best. Compare building a car with painting a landscape. |
| 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'. |
| 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. |
| 3192 | Basic logic can be done by syntax, with no semantics [Gödel, by Rey] |
| Full Idea: Gödel in his completeness theorem for first-order logic showed that a certain set of syntactically specifiable rules was adequate to capture all first-order valid arguments. No semantics (e.g. reference, truth, validity) was necessary. | |
| From: report of Kurt Gödel (On Formally Undecidable Propositions [1931]) by Georges Rey - Contemporary Philosophy of Mind 8.2 | |
| A reaction: This implies that a logic machine is possible, but we shouldn't raise our hopes for proper rationality. Validity can be shown for purely algebraic arguments, but rationality requires truth as well as validity, and that needs propositions and semantics. |
| 19399 | Prime matter is nothing when it is at rest [Leibniz] |
| Full Idea: Primary matter is nothing if considered at rest. | |
| From: Gottfried Leibniz (Aristotle and Descartes on Matter [1671], p.90) | |
| A reaction: This goes with Leibniz's Idea 13393, that activity is the hallmark of existence. No one seems to have been able to make good sense of prime matter, and it plays little role in Aristotle's writings. |
| 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). |