1. Standard memberAgerg
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    24 Feb '15 19:527 edits
    It has been established previously (by some pretty talented logicians) that omnipotence is logically compatible with libertarian freewill subject to all parties agreeing not that

    1) Necessarily, God knows P (precluding ¬P)

    but that instead

    2) Necessarily, if P then God knows P.

    This does make uneasy sense Reveal Hidden Content
    I suppose we can imagine some god sitting back on an orthogonal timeline free to fast-forward or rewind our own, and observe what we do (such that from our perspective he always knows))
    but when a theist turns round and tells us something like:
    3) "God knew what we would choose to do before he created the universe"

    how can it be established they are referring to convention (2)?
    To me the proposition that prior to even instantiating a timeline T where X can have truth values, he knows everything about every possible truth value of X seems to render absurd (or better moot) any notion of "if X ...". Indeed X has a known and invariant truth value at every point on T.

    To me the suggestion in (3) suggests only (1). How am I mistaken?




    -------------------
    Sorry about the rubbish title - not allowed to change it (and I suspect it could be refactored to have half its length and twice the legibility)
  2. Joined
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    24 Feb '15 20:12
    Originally posted by Agerg
    It has been established previously (by some pretty talented logicians) that omnipotence is logically compatible with libertarian freewill subject to all parties agreeing not that

    1) Necessarily, God knows P (precluding ¬P)

    but that instead

    2) Necessarily, if P then God knows P.

    This does make uneasy sense (I suppose we can imagine some god sitting ...[text shortened]... rd any notion of "if X ..."

    To me the suggestion in (3) suggests only (1). How am I mistaken?
    I remain unconvinced.

    Lets take your example of a god outside of our time who can fast-forward,
    and rewind the universe and thus can see what is going to happen...


    Ok, lets have events A and B inside the time-line of our universe.

    A happens some time interval before B [let's say 1000 years] as measured inside
    our universe [in a suitably relevant reference frame].


    Event A is god manifesting and making a cryptic [so that it cannot be self fulfilling]
    but completely unambiguous highly specific and precise prediction about what
    will happen in 1000 years time [event B].


    God does this by winding the universe forwards to event B.

    Observing event B occur.

    Winding the universe back to time A and making the prediction about event B.

    Then the universe winds back forwards to event B.



    For gods prediction to be 100% guaranteed to be correct, the time-line must be
    fixed between event A and event B because otherwise as the universe winds forwards
    the second time events could unfold differently causing the prediction to be false.

    It doesn't matter if all points in time exist at once or only an ever changing present
    moment, if god can see what happens in event B and can tell us 1000 years
    before hand [or any arbitrarily long period before event B] exactly what is going to
    happen then what is going to happen cannot change and thus must be predetermined.

    If this is true then the entire universe must be predetermined as god could do this for
    any and all possible events at any and all possible times.



    In the given example I don't see that omniscience exists without there also necessarily
    being predetermination for all events in the universe.

    As such, if it has been shown that omnipotence is logically compatible with libertarian freewill
    then this example doesn't demonstrate that.
  3. Cape Town
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    24 Feb '15 20:21
    Originally posted by googlefudge
    .....what is going to happen then what is going to happen cannot change and thus must be predetermined.
    What do you mean by 'predetermined'? Do you mean something in the past causes something in the future, or are you simply stating that there is only one future?
    Today, you posted a post with the word 'predetermined' in it. Is there another reality in which you did not? If there is no other reality, then how does my observing that you made that post not make it predetermined?
  4. Cape Town
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    24 Feb '15 20:26
    Tomorrow, I will either post on RHP or I will not post on RHP. Only one of those realities will come to pass. Lets call the one that will come to pass X. Is X predetermined? If I knew now what X was, would that make it predetermined? Does predetermined merely imply foreknowledge? Or is there more to it?
  5. Standard memberDeepThought
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    24 Feb '15 20:34
    Originally posted by googlefudge
    I remain unconvinced.

    Lets take your example of a god outside of our time who can fast-forward,
    and rewind the universe and thus can see what is going to happen...


    Ok, lets have events A and B inside the time-line of our universe.

    A happens some time interval before B [let's say 1000 years] as measured inside
    our universe [in a suitably re ...[text shortened]... is logically compatible with libertarian freewill
    then this example doesn't demonstrate that.
    The difficulty with your example is that you have God intervening in the universe at the time of event A to record his prediction of event B. This makes event A causally dependent on event B. So you've added an intervention which breaks causality within this universe. But omniscience doesn't imply any ability or desire to intervene. Certainly omnipotence does, but that is not what is being discussed. Since God is presumably outside of the universe you can only create a causality problem by insisting on an intervention.
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    24 Feb '15 20:34
    Originally posted by twhitehead
    What do you mean by 'predetermined'? Do you mean something in the past causes something in the future, or are you simply stating that there is only one future?
    Today, you posted a post with the word 'predetermined' in it. Is there another reality in which you did not? If there is no other reality, then how does my observing that you made that post not make it predetermined?
    Only one future.

    Lets say for the sake of argument that libertarian free will exists.

    And I have a choice to make.

    The outcome of which will be the event B mentioned in my last post.

    The universe runs through the first time [with god watching to see
    what happens] and I make a choice. [and given that I have free will
    of the libertarian sort I could have necessarily chosen other than I did.]

    God sees that I make a particular choice, winds the universe back to
    time A and makes the prediction that I will make this choice at time B.

    Now the universe winds forwards again to time B, and I have a choice
    to make. I have libertarian free will, and this time choose differently.

    Gods prediction is now wrong.

    And it's worse, because I am not the only agent with free will in the 1000
    years between A and B and all the other agents with free will between the
    two times can also make different decisions and thus the time-line will change
    and I never face the choice in the first place [if I even still exist].


    The only way this cannot happen is if all the events are predetermined and
    unchangeable.

    A fully non-probabilistic deterministic universe.

    There is only one invariant time-line.


    I hope that makes my post clearer?
  7. Joined
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    24 Feb '15 20:45
    Originally posted by DeepThought
    The difficulty with your example is that you have God intervening in the universe at the time of event A to record his prediction of event B. This makes event A causally dependent on event B. So you've added an intervention which breaks causality within this universe. But omniscience doesn't imply any ability or desire to intervene. Certainly omnipot ...[text shortened]... outside of the universe you can only create a causality problem by insisting on an intervention.
    We are dealing with the idea that god can know the outcome of event B at
    any time with respect to our universe.

    Otherwise you are just saying that god can know the outcome of B when B happens.

    Which isn't at all remarkable.

    And the problem isn't caused by the intervention.

    The problem is caused by god winding the universe backwards and forwards [or having
    the ability to do so] and seeing the exact same thing happen every time like god is
    watching a movie.

    If god can KNOW at time A what will happen at time B in our universe.
    And that is achieved as per the example by winding the universe backwards and forwards
    then the problem exists if god pops in to make it's prediction or not.
    You still have a second* run at event B which cannot result in a different choice being made.

    *Or nth run depending on how many times god views the future.



    Incidentally...
    You also have problems with the statement god is outside of the universe.
    Universe means everything.
    You cannot have an outside unless you are redefining what the universe is.
    In which case you need to do so, so we can tell if that has any relevant implications.
  8. Standard memberAgerg
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    24 Feb '15 20:522 edits
    Originally posted by googlefudge
    I remain unconvinced.

    Lets take your example of a god outside of our time who can fast-forward,
    and rewind the universe and thus can see what is going to happen...


    Ok, lets have events A and B inside the time-line of our universe.

    A happens some time interval before B [let's say 1000 years] as measured inside
    our universe [in a suitably re ...[text shortened]... is logically compatible with libertarian freewill
    then this example doesn't demonstrate that.
    As per my opening post, my problem stems from the knowledge of P prior to even creating the universe.

    If we supposed, instead, that prior to creating the universe (from his own perspective) any outcomes are unknown. Then there is nothing wrong with imagining he then goes and creates a universe (equipped with timeline), sits back, smokes a cuban, looks at the timeline he just made and goes "ooh look ... he chose to do P!" Meanwhile, from our perspective, we have yet to reach that point in the timeline where we actually go ahead and make that choice. It would still seem, from our perspective there is an agent that knows we will do P before we have even made the choice - an agent that knows every choice we will ever make (justifying omniscience in this limited sense). Yes the timeline is fixed (from God's perspective), but only because we each played our own parts in fixing it by making choices at the appropriate time.

    And yes I am trying very hard to accommodate the theist here, but I still have to throw out the notion that he could know the contents of a timeline before he created it (from his own perspective)
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    24 Feb '15 21:181 edit
    Originally posted by Agerg
    As per my opening post, my problem stems from the knowledge of P prior to even creating the universe.

    If we supposed, instead, that prior to creating the universe (from his own perspective) any outcomes are unknown. Then there is nothing wrong with imagining he then goes and creates a universe (equipped with timeline), sits back, smokes a cuban, looks at t ...[text shortened]... on that he could know the contents of a timeline before he created it (from his own perspective)
    Ok, as I understand it, modal logic necessitates that for a statement to necessarily be
    true it must be true under all possible universes.


    So we have god lounging about in whatever plane of existence god lounges about in.

    And god then creates the universe...

    Possibility 1.

    All times exist in this universe simultaneously, and god can see the entire thing at once
    and see past present and future all at the same time.

    God can look at event B and see the outcome and simultaneously look at point A
    before B occurs knowing that event B will occur while the beings in the universe at
    point A don't and cannot know this and also have not yet chosen to do B.

    However such a universe appears to me to be the very definition of predetermined as it
    is completely static and unchanging, with the past present and future all instantly determined
    at the point of creation.

    This is like having an entire movie reel laid out in front of you so you can see every
    frame at the same time.


    Possibility 2.

    The universe only exists as an ever changing moment in time, equivalent to watching
    a film on a screen, with only one frame on view at any one time.

    To see event B in such a universe god must play the universe from the start to point
    B and then observe it.

    Thus when point A is passed god does not yet know what will happen at point B.

    God would know at point A ONLY if god then winds the universe back and watches it again.



    In both cases the universe looks non-randomly deterministic.
  10. Standard memberAgerg
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    24 Feb '15 21:353 edits
    Originally posted by googlefudge
    Ok, as I understand it, modal logic necessitates that for a statement to necessarily be
    true it must be true under all possible universes.


    So we have god lounging about in whatever plane of existence god lounges about in.

    And god then creates the universe...

    Possibility 1.

    All times exist in this universe simultaneously, and god can see th ...[text shortened]... e back and watches it again.



    In both cases the universe looks non-randomly deterministic.
    Wrt possibility 1, I agree ... it would indeed be like a movie reel laid out in front of [God] so [he] can see every frame at the same time. But the essential feature here is that the movie reel should not be known prior to its creation (otherwise, as per my op, that would be predetermining our choices). From our perspective we can just go ahead and choose what we like, and some nosey old god is out there watching what we did. Moreover this god doesn't have to "wait until we actually do it" because he sits on his own timeline and pokes around when he's good and ready, safe and sound with the knowledge that the universe played out in its entirety without any action or intervention on his part at the point he caused it to be.

    It is us, and everyone/thing else in the universe going about and fixing this timeline for God when he eventually gets round to looking at it.
  11. Standard memberDeepThought
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    24 Feb '15 21:38
    Originally posted by googlefudge
    We are dealing with the idea that god can know the outcome of event B at
    any time with respect to our universe.

    Otherwise you are just saying that god can know the outcome of B when B happens.

    Which isn't at all remarkable.

    And the problem isn't caused by the intervention.

    The problem is caused by god winding the universe backwards and forw ...[text shortened]... erse is.
    In which case you need to do so, so we can tell if that has any relevant implications.
    In your example as originally stated event A was God leaving a prediction of the later event B within this universe. Universe I agree should mean "all things" but no longer does, otherwise statements such as "Our universe is a brane within a higher dimensional bulk" make no sense.

    There is no logical contradiction between omniscience and free will.

    What was shown in the other threads was that one cannot form a contradiction from the following statements:

    Let P be some proposition such as "I have toast for breakfast tomorrow.".
    Let K be the proposition "God knows P from the beginning of time"
    Let □ be the modal operator meaning necessarily (Unicode 25A1).

    I) □(P->K) is the statement: necessarily, if I have toast for breakfast tomorrow then God has known that I will have toast for breakfast tomorrow since the beginning of time. This encapsulates omniscience.

    II) ¬□P is the statement: I will not necessarily have toast for breakfast tomorrow. This encapsulates free will (whether it is freedom to act or libertarian free will).

    Statement (I) is equivalent [1] to

    III) □P -> □K

    and it is not possible to derive a logical contradiction from statements II and III. Note that □(P -> K) is the strict conditional I referred to in the other thread. Here the logical if actually does mean that P entails K.

    [1] There is a subtlety here, I think the step from I to III depends on which form of modal logic is used, although even if we cannot do that then I see no way of demonstrating a contradiction.
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    24 Feb '15 21:51
    Originally posted by DeepThought
    In your example as originally stated event A was God leaving a prediction of the later event B within this universe. Universe I agree should mean "all things" but no longer does, otherwise statements such as "Our universe is a brane within a higher dimensional bulk" make no sense.

    There is no logical contradiction between omniscience and free ...[text shortened]... is used, although even if we cannot do that then I see no way of demonstrating a contradiction.
    I am going to have to think about this, but I suspect that it fails to something like this...


    A) IF statement I) is true THEN the universe must necessarily be non-randomly deterministic.

    B) IF statement II) is true THEN the universe must necessarily NOT be non-randomly deterministic.

    C) Therefore statement I) and II) cannot both be true.
  13. Standard memberDeepThought
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    24 Feb '15 22:10
    Originally posted by googlefudge
    I am going to have to think about this, but I suspect that it fails to something like this...


    A) IF statement I) is true THEN the universe must necessarily be non-randomly deterministic.

    B) IF statement II) is true THEN the universe must necessarily NOT be non-randomly deterministic.

    C) Therefore statement I) and II) cannot both be true.
    I agree with statement B. If ¬□P then I have freedom to act differently, even if I don't have free will at some metaphysical level and it is just random variation. Statement A is tricky. Your approach of attempting to show that it violated causality is the obvious one, but I think you'd be hard pressed to find a theist who would accept their God being anything other than omnipotent and therefore not bound by anything.
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    24 Feb '15 22:18
    Originally posted by DeepThought
    I agree with statement B. If ¬□P then I have freedom to act differently, even if I don't have free will at some metaphysical level and it is just random variation. Statement A is tricky. Your approach of attempting to show that it violated causality is the obvious one, but I think you'd be hard pressed to find a theist who would accept their God being anything other than omnipotent and therefore not bound by anything.
    Whoa... you mean my argument not only has to be logically valid, but convincing to
    irrational theists who don't understand logic as well??

    When did that happen.... 😛 😉


    If we use the analogy of a mechanical clock for the non-random deterministic universe.

    Then god can from outside this universe come in and poke around and change stuff
    to it's hearts content.

    However the universe would still be non-random and deterministic.

    When left alone by god the universe has only one possible predictable path.

    This allows god to tinker, to perform miracles, but still maintain the ability
    of absolute prediction.

    As the consequences of the changes god makes will be predictable to god beforehand.
  15. Standard memberDeepThought
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    25 Feb '15 00:44
    Originally posted by googlefudge
    Whoa... you mean my argument not only has to be logically valid, but convincing to
    irrational theists who don't understand logic as well??

    When did that happen.... 😛 😉


    If we use the analogy of a mechanical clock for the non-random deterministic universe.

    Then god can from outside this universe come in and poke around and change stuff
    to ...[text shortened]... ediction.

    As the consequences of the changes god makes will be predictable to god beforehand.
    Well if you can convince the theists then the argument must be watertight.

    We have free will entailing that for some action A, ¬□A. So it is enough for what I want to talk about if the variation is random. I'm asking to set aside free will for now and just have a non-predetermined universe, since that does the same work as libertarian free will as far as predictive omniscience is concerned.

    Maybe we should consider possible models for the universe. If, for the moment, we go along with Everett's many universes interpretation of quantum mechanics then the language of physics maps nicely to the possible worlds semantics of modal logic. So consider some action A that I can take in the subset of possible worlds were it is possible for me to do A. In some of them I do A and in others I do not. Since all the universes are equally real and God is outside of all this God simply has to know the initial conditions of the universe and omniscience is a trivial problem in solving the Schrödinger equation for the entire universe.

    So let's suppose that Everett's many universes interpretation isn't the correct one and that the other universes in it aren't real, they are just what would have happened. I have this mental image of a tree of possible universes and a dot moving up the tree to indicate which the actual universe is. Now God's omniscience allows him to know the entire tree, the tricky part is that he has to know where the dot is before it gets there to know whether I'll do A or not. Since whenever it gets to a fork, which may involve a continuous infinity of choices, the dot takes a random route at face value this cannot be known head of time.

    However, God is portrayed by the theists as being outside of time. For the sake of being able to discuss this let us imagine that God has a divine time so that we can say things like before and after. When he creates the universe he sees the entire tree of possibilities with the entire evolution of the actual universe highlighted as a brighter line which is the line traced out by my dot which marks the actual universe. That line can be selected randomly and God can know it all at once. This is as close as I can get to predictive omniscience.

    I don't think this would satisfy the theists though, because I don't think it would be possible for God to intervene in the world, since that would change the line. It also stretches a point with the statement: "God knows everything ahead of time.". I suppose you could imagine God not being happy with the randomly chosen line and intervening at some point in the tree to change the subsequent line. But that must change who exists - God intervening prevents some people who would have existed from existing, from his point of view they already existed and ceased to after his intervention changes the line segment.

    This is about as far as I can get.
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