• Luke
    900
    Following from this and other discussions at this site, I wanted to lay out my view of why Eternalism logically precludes motion. After some consideration, I believe that the best way to do this and to present the critical differences between the two major opposing temporal ontological theories of Eternalism and Presentism is via a discussion of the differences between Eternalism and the Moving Spotlight Theory.

    Firstly, a definition of terms:

    THE PASSAGE OF TIME
    A-Theory: Time passes; the passage of time is real
    B-Theory: Time doesn't pass; the passage of time is not real

    'According to The B Theory, time is very much like the dimensions of space. Just as there are no genuine spatial properties (like being north), but, rather, only two-place, spatial relations (like north of), so too, according to the B Theorist, there are no genuine A properties. According to The A Theory, on the other hand, time is very different from the dimensions of space. For even though there are no genuine spatial properties like being north, there are, according to the A Theorist, genuine A properties; and time, unlike space, can truly be said to pass, according to The A Theory.'
    https://plato.stanford.edu/entries/time/#PreEteGroUniThe

    'The difference between A-theorists and B-theorists is often described as a dispute about temporal passage or 'becoming' and 'progressing'. B-theorists argue that this notion is purely psychological. Many A-theorists argue that in rejecting temporal 'becoming', B-theorists reject time's most vital and distinctive characteristic. It is common (though not universal) to identify A-theorists' views with belief in temporal passage.'
    https://en.wikipedia.org/wiki/B-theory_of_time

    ONTOLOGY/EXISTENCE
    Eternalism: 'objects from both the past and the future exist just as much as present objects.'
    Presentism: 'only present objects exist.'

    However, there is more to Presentism than what exists at the present moment, since the present moment is dynamic:

    'Presentism is the view that only present things exist and what’s present changes'. (My emphasis)

    Presentism therefore entails temporal passage, i.e. the A-Theory.

    ONTOLOGICAL HYBRIDS:
    Growing Block Theory: 'According to the growing block universe theory of time (or the growing block view), the past and present exist while the future does not. [...] By the passage of time more of the world comes into being; therefore, the block universe is said to be growing. The growth of the block is supposed to happen in the present, a very thin slice of spacetime, where more of spacetime is continually coming into being.'

    The Growing Block theory combines Eternalism's existence of the past with Presentism's existence of the present and non-existence of the future.

    In short, the Growing Block theory is a hybrid of Eternalism in the past + Presentism in the present/future.

    Moving Spotlight Theory: 'the Moving Spotlight Theory combines Eternalism — the doctrine that past, present, and future times all exist — with “objective becoming.” The claim that there is objective becoming has two parts. First, facts about which time is present are non-relative. That is, even if in some sense each time is present relative to itself, only one time is absolutely present. That time, and only that time, glows with a special metaphysical status. And second, which instant is absolutely present keeps changing. The NOW moves along the series of times from earlier times to later times.'
    (Relativity and the Moving Spotlight - Bradley Skow)

    'We are naturally tempted to regard the history of the world as existing eternally in a certain order of events. Along this, and in a fixed direction, we imagine the characteristic presentness as moving, somewhat like the spot of light from a policeman's bull's eye traversing the fronts of the houses in a street. What is illuminated is the present, what has been illuminated is the past, and what has not yet been illuminated is the future.'
    (C. D. Broad (1923))

    In short, the Moving Spotlight theory is a hybrid of Eternalism + Presentism/A-Theory.

    More astute readers might now be asking themselves the following question: If Eternalism already contains all of existence at all times, then what can Presentism possibly add to this ontology? For example, Huw Price appears to reject Presentism on these grounds in this video. The answer is quite obvious. What Presentism/A-Theory adds over and above the ontology of Eternalism is: temporal passage. Without temporal passage and the A-Theory, Eternalism is equivalent to the four-dimensional block universe. In other words, the block universe or four-dimensionalism is Eternalism + the B-Theory, which is the logically natural state of Eternalism, as far as I understand it. That is, Eternalism + the B-Theory is just Eternalism, whereas Eternalism + the A-Theory is the Moving Spotlight theory.

    Some members of this site, including @SophistiCat and @Douglas Alan have previously claimed that Eternalism does not preclude motion. In that case, my question is: when does motion occur according to Eternalism? It cannot be at the present moment, because motion or temporal passage at the present moment implies the A-Theory, making it not Eternalism, but the Moving Spotlight theory instead. So, does Eternalist motion occur in the past or the future somehow?
  • noAxioms
    875
    I wanted to lay out my view of why Eternalism logically precludes motion.Luke
    I smell a begging argument coming on. You did this fairly large post, but then never actually get around to this point until the last couple sentences.

    Some members of this site, including SophistiCat and @Douglas Alan have previously claimed that Eternalism does not preclude motion.
    You can add me to that list. At noon, the mug has coffee in it. At 1pm the mug is in the dishwasher. How is that not motion of the mug?

    In that case, my question is: when does motion occur according to Eternalism?
    Somewhere between noon and 1 obviously (in my example). Every moment of it in fact, since at no time is any object actually stationary, what with Earth spinning and accelearting and all.

    It cannot be at the present moment, because motion or temporal passage at the present moment implies the A-Theory, making it not Eternalism, but the Moving Spotlight theory instead. So, does Eternalist motion occur in the past or the future somehow?
    There's the begging I smelled. Everything here are A-series references which assumes the conclusion you're trying to demonstrate.
  • Luke
    900
    "It cannot be at the present moment, because motion or temporal passage at the present moment implies the A-Theory, making it not Eternalism, but the Moving Spotlight theory instead. So, does Eternalist motion occur in the past or the future somehow?"
    - Luke

    There's the begging I smelled. Everything here are A-series references which assumes the conclusion you're trying to demonstrate.
    noAxioms

    Please enlighten me as to the difference between Eternalism and the Moving Spotlight theory. You seem to be implying that temporal passage is possible under Eternalism? How so?
  • Luke
    900
    At noon, the mug has coffee in it. At 1pm the mug is in the dishwasher. How is that not motion of the mug?noAxioms

    How does the mug move from, let's say, your desk to the dishwasher?
  • noAxioms
    875
    Please enlighten me as to the difference between Eternalism and the Moving Spotlight theory.Luke
    Moving spotlight (and pretty much the rest of your list) has a preferred moment. Eternalism does not.
    You seem to be implying that temporal passage is possible under Eternalism? How so?
    I implied no such thing. I said there is movement. I made no reference to temporal passage, which again is a term only meaningful to views that posit a preferred moment.

    The mug moves probably by me carrying it there. That's probably not the answer for which you're looking, but I don't know what else you might be asking with that question.
  • ChatteringMonkey
    545
    You seem to be implying that temporal passage is possible under Eternalism? How so?Luke

    The whole spacetime-block is 'static' viewed from the outside, but with-in the model, time and change are part of how things are situated in that space-time block. You have things at postion X1 en time T2, and then at position X2 en T2. This is change.

    The difference with presentism is mostly that an eternalist wants to say that the past and future are equally real as the now, whereas for a presentist only the now exists.

    The problem is with the word 'real' really. A presentist wants to start from the more or less intuitive and practical view that what is real is what we experience, and that is only the now. An eternalist bases the notion of real more on science, and Einsteins theory of special relativity, where the concept of a now doesn't really make sense.
  • Luke
    900
    Moving spotlight (and pretty much the rest of your list) has a preferred moment. Eternalism does not.noAxioms

    What do you mean by "a preferred moment"?
  • Luke
    900
    The difference with presentism is mostly that an eternalist wants to say that the past and future are equally real as the now, whereas for a presentist only the now exists.ChatteringMonkey

    I addressed this in the OP.

    Presentism is not just about existence; it also entails the A-Theory and the reality of temporal passage. Eternalism eschews temporal passage (A-Theory) and with temporal passage it becomes the Moving Spotlight theory.
  • ChatteringMonkey
    545
    Presentism is not just about existence; it also entails the A-Theory and the reality of temporal passage.Luke

    What do you mean with the reality of temporal passage?
  • sime
    510
    I disagree that presentism entails the reality of passage, because presentism might interpret the word "now" as being an indexical that cannot refer to the same set of affairs twice. If that is the case, then temporal passage cannot be referred to.

    Recall Heraclitus, who said that it is impossible to step twice into the 'same' river twice. Here he is implying that the meaning of "same river" refers to a constant, say a static memory, relative to which the state of the actual river can be said to have changed. In contrast, if it is denied that the meaning of "the present" is fixed, then the river cannot be said to have changed relative to the present.

    If the phrase "the present" is always substituted for the current international atomic time, then the sentence "the present has changed" is no longer grammatically permissible.
  • Luke
    900
    What do you mean with the reality of temporal passage?ChatteringMonkey

    See the OP section on The Passage of Time.
  • Luke
    900
    I disagree that presentism entails the reality of passage, because presentism might interpret the word "now" as being an indexical that cannot refer to the same set of affairs twice. If that is the case, then temporal passage cannot be referred to.sime

    I tend to agree that a true presentist who rejects the existence of the past and future would be unable to judge which time is present. However, in reality, I think we are all able to ascertain this and can talk meaningfully about temporal passage. But this is not the focus of this discussion.

    Edited to add: Actually, I think a presentist can discuss the past and future without believing that things exist at those times.
  • sime
    510
    I tend to agree that a true presentist who rejects the existence of the past and future would be unable to judge which time is present. However, in reality, I think we are all able to ascertain this and can talk meaningfully about temporal passage. But this is not the focus of this discussionLuke

    For similar reasons I disagree that a denial of passage of time involves the denial of past and future, since "past" and "future" can similarly be interpreted as indexicals.

    We can say that the state of the river has changed relative to the state of a photograph. But if the state of the river is our notion of "the present", then we can no longer say that the river has changed relative to the present.

    I believe that McTaggart was making a similar deflationary argument when he concluded the unreality of the A series.
  • Luke
    900
    For similar reasons I disagree that a denial of passage of time involves the denial of past and future, since "past" and "future" can similarly be interpreted as indexicals.

    We can say that the state of the river has changed relative to the state of a photograph. But if the state of the river is also our notion of "the present", then we can no longer say that the river has changed relative to the present.
    sime

    You say that a denial of passage need not involve a denial of the past and future, but if "the state of the river is also our notion of "the present", then isn't this a denial of past and future? This seems to imply that we have no 'notion' of past or future states by which to judge that the present has changed.
  • Luke
    900
    I believe that McTaggart was making a similar deflationary argument when he concluded the unreality of the A series.sime

    McTaggart's argument is that a time cannot have the properties of being past, present and future, but with temporal passage it does have all three properties (over time). The flaw in the argument is that it doesn't have all three properties at the same time.
  • ChatteringMonkey
    545
    See the OP section on The Passage of Time.Luke

    Yes it still isn't entirely clear what your mean with it, does it mean that time is an independent metaphysical thing acting on the universe, or do things just change and we measure that change in units of time for our convenience (we invented the concept basically)?

    Either way, I don't see anything that couldn't fit into an eternalist view, other than the disagreement about what is real.
  • Luke
    900

    Quoting from the OP:
    'The difference between A-theorists and B-theorists is often described as a dispute about temporal passage or 'becoming' and 'progressing'. B-theorists argue that this notion is purely psychological.'

    I do not mean by it "that time is an independent metaphysical thing acting on the universe."
  • ChatteringMonkey
    545


    Yes I get that, what is the point?

    If B-theorist eternalist are right, and we are beings that only experience one moment in time, then we would experience the block-universe as passage of time. I just don't see what the argument is that is presented against that?
  • Luke
    900
    If B-theorist eternalist are right, and we are beings that only experience one moment in time, then we would experience the block-universe as passage of time.ChatteringMonkey

    But that passage is not real, right? Eternalists don't believe that time really passes, right? So, I want to know how motion is supposedly accounted for under Eternalism (by those who believe that Eternalism allows for motion).
  • sime
    510
    You say that a denial of passage need not involve a denial of the past and future, but if "the state of the river is also our notion of "the present", then isn't this a denial of past and future? This seems to imply that we have no 'notion' of past or future states by which to judge that the present has changed.Luke

    All that is being denied is a notion of "temporal passage" that is distinct from the passage, of say, of a speeding train relative to the readings on a stop-watch. In other words, that the notion of temporal passage reduces to relations among appearances, which can also include whatever experiential content one has temporarily assigned to the notions of "past" and "future".

    If understood indexically, the past is always the past and the future is always the future, for yesterday is always yesterday, and tomorrow is always tomorrow....
  • ChatteringMonkey
    545
    But that passage is not real, right? Eternalist's don't believe that time really passes, right? So, I want to know how motion is supposedly accounted for under Eternalism (by those who believe that Eternalism admits of motion).Luke

    But the block-universe incorporates motion, in space and time? Isn't it a given that things change in space and time in a 4-dimensional block-universe?
  • Luke
    900
    But the block-universe incorporates motion, in space and time? Isn't it a given that things change in space and time in a 4-dimensional block-universe?ChatteringMonkey

    How can it be, when B-theorist eternalists reject the reality of temporal passage?
  • Luke
    900
    If understood indexically, the past is always the past and the future is always the future, for yesterday is always yesterday, and tomorrow is always tomorrow....sime

    But yesterday was a different day to today, just as tomorrow will be.

    Sorry @Sime, but this might be better suited to a new discussion, as I would like to focus here on Eternalism, motion, and the Moving Spotlight theory.
  • Luke
    900
    Do you consider Eternalism and the Moving Spotlight theory to be equivalent?
  • ChatteringMonkey
    545
    How can it be, when B-theorist eternalists reject the reality of temporal passage?Luke

    I don't get how you would interpret it that way, since time is literally one of the dimensions in the block-universe. What do you think that dimension signifies otherwise?
  • Luke
    900
    What do you thing that dimension signifies otherwise?ChatteringMonkey

    Existence only. The existence of all things, minus passage.
  • ChatteringMonkey
    545
    Do you consider Eternalism and the Moving Spotlight theory to be equivalent?Luke

    No, the moving spotlight theory gives a special metaphysical status to the present whereas eternalism does not, I guess, i'm not exactly an expect on that.
  • sime
    510
    But yesterday was a different day to today, just as tomorrow will be.
    .
    Luke

    According to the indexical theory, to say "tomorrow will become yesterday" is to merely to express an intention to redefine the meaning of "yesterday", "today" and "tomorrow" so as to give the illusion of temporal passage. In other words, the indexical theory is an anti-realist stance. It's relevant to the issues you raise, because the use of tenses as indexicals is routinely overlooked in philosophical discussions.
  • ChatteringMonkey
    545
    Existence only.Luke

    Yeah but existence in the block-universe is defined in four dimensions, that is probably what you are not realising?
  • Luke
    900
    No, the moving spotlight theory give a special metaphysical status to the presentChatteringMonkey

    What do you mean by 'special metaphysical status'? Is it any different to what you mean when you say "we are beings that only experience one moment in time"? When else can we experience things except in the present moment?
  • Luke
    900
    Yeah but existence in the block-universe is defined in four dimensions, that is probably what you are not realising?ChatteringMonkey

    I'm well aware, thanks.
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