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Would the existance of an omniscient being prove that free will is non-existant?

  1. Sep 23, 2006 #1
    I have read the following arguement as proof that if an omiscient being can see the future, free will does not exist.

    1. An infallible, omniscient, being exists. [Assumption]
    2. This being has foreknowledge that event 'A' will occur. [Definition of omniscience]
    3. 'A' must occur. [Definition of infallible]
    4. I cannot choose to do any action which would make it so that 'A' does not occur. [Points, 1, 2, 3]
    5. I lack free will. [Point 4]

    Does this arguement hold water?

    For the sake of the above argument, please forget what quantum mechanics may or may not prove, etc. Before given the information above, if we assume that free will can exist, do the points above alone prove that it can not. Thanks.
  2. jcsd
  3. Sep 23, 2006 #2


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    It's pretty much a moot point since there is no supreme being, but this actually belongs in the Philosophy section.
  4. Sep 24, 2006 #3
    Although you cannot choose to do an action that makes 'A' not occur, I don't see how it follows that you do not choose for 'A' to occur. Perhaps the omniscient being's foreknowledge that 'A' will occur is the result of the being knowing that you will choose to do 'A'. If so, then if you had chosen to do something other than 'A', the omniscient being would have had foreknowledge that this other thing would occur.

    So there's a decision to be made: does the being's knowledge determine what will happen, or does what will happen determine the being's knowledge. If the former, no free will. If the latter, then there can be free will even if there is an omniscient being, because free choices determine, in part, the content of that being's knowledge.

    And here's a second, more radical reply, that is independent of the first: if the future does not exist yet, then an omniscient being does not know what will happen in the future (because omniscience only requires knowing everything about what there is). In this case, the omniscient being will know that A occurs when A actually occurs. And even if the omniscient being is smart enough to be able to predict very reliably that A occurs, still this prediction does not amount to the being's making it the case that A occurs.
  5. Sep 24, 2006 #4


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    You don't need a supreme being to invoke this logic.

    As soon as you allow for the ability to see future events - through any means, you run into a contradiction with free will.
  6. Sep 25, 2006 #5
    X-Ray: assuming there is free will and assuming there is an omniscient being, then I would say yes, the omnisient being - who is presumably outside of time - can have complete knowledge of someone's free choice. I see no contradiction there at all. What for us would seem like foreknowledge is to an omniscient being just knowledge.

    The difficulty arises when you try to reconcile omniscience, not with the choices that are made but with those that aren't!

    First, to define some concepts.

    Omniscience – all knowing. By extension this would, in my view, have to mean the totality of all knowledge. Such knowledge covers everything that is, everything that has been, everything that will be, everything that could be and everything that might have been.

    An omniscient being - a mind that knows, in effect, every conceivable experience of reality, both possible and actual.

    To say, as NickJ did, that only the present might exist is an interesting notion - but it seems to place an ad hoc limitation on knowledge - one that would have to apply to the past too. Historians and weather forcasters would soon be out of a job.

    The key to this is not the distinction between past and future, but the distinction between the actual and the possible.

    In terms of omniscience, does it make sense to distinguish between actual and possible experiences?

    The excercise of free will means that some experiences are had, while others get avoided. Now, if a possible experience is avoided, can it be known as clearly as an actual one?

    If an omniscient being does know possible experiences as vividly as actual ones, what is the knowledge based on? Or to flip that argument: if possible experiences are known fully, in what sense have they been avoided?

    In human terms, free will means choosing one experience over another. To use a biblical analogy, if Eve had chosen not to bite into the apple, she could never have known what it tasted like. By choosing as she did she experienced biting into the apple.

    An omniscient being would have to know, in full, the experience of biting into the apple and leaving Eden. The same being would also have to know the experience of not biting into the apple and staying in Eden. Both sets of experiences would be included in the totality of knowledge. By necessity therefore, free will does not increase knowledge but has to deny it.

    Conclusions: omniscience must, by necessity, include all possible experiences. For free will to exist, some experiences must be denied. If any possible experience is denied, there can be no omniscience. However, if omniscience exists, all possible experiences are fully known because they have been had and free will must be redundant.

    If there is an omniscient being, then all possible experiences must be known to it. For any experience to be known in full, it must in fact be had by someone. Free will, however, requires that some experiences are denied. If no experiences are being denied, then free will cannot exist. Therefore free will and omniscience cannot be compatible.

    Free will is only viable if some experiences are in fact avoided and are not known by anyone. Omniscience is only viable if all possible experiences actually occur.

    The most powerful being can know in full all past, present and future experiences - but only those that are actually had. To know in full of a possible experience that is never experienced is a contradiction.

    It seems that you can have free will or an omniscient being, but not both.

    If I had to make a choice, I would plum for the omniscient being.
    Whether that is a free choice is another matter... :)
    Last edited: Sep 25, 2006
  7. Sep 25, 2006 #6
    Cannot the omniscient being freely will not to know "all" actual experiences of another free will entity, yet maintain potential of such knowledge, thus allowing both to exist ?
  8. Sep 26, 2006 #7
    This conclusion is unfortunately based on faulty logic (but admittedly many people including myself do make this mistake, since the correct logical argument is not obvious unless one studies it carefully and rigorously - it was a long time before I understood my error). As long ago as the 6th century, Boethius realised that an atemporal being could logically know everything about the temporal world without there being any necessary contradiction with the notion of free will.

    The important thing to understand is that event A happening is the "cause" of the omniscient being "knowing" that A, not the other way around (ie the fact that the omniscient being "knows" that A does not "cause" A to happen), hence there is not necessarily any inconsistency between omniscience and free will.

    The logical error in the OP argument is known as the "transfer of necessity" in step 3 - just because an entity knows that A "will" occur does not entail that A "must" occur (ie is logically necessary).

    In other words, A can be logically contingent (ie dependent on free will), and the entity can logically still "know that A" in advance.

    For a full discussion see


    and for an excellent explanation of the logical argument involved see


    Best Regards
    Last edited: Sep 26, 2006
  9. Sep 26, 2006 #8


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    I don't see how this invalidates my claim (though it's possible you didn't mean to pick on my statement specifically). You don't need to postulate an omniscient being, all you need to postulate is the ability to see the future - and you have the conditions required to generate the apparent paradox. Granted, it is an apparent paradox, which you go on to show:

    I was thinking like this too, but I couldn't articulate it.

    If I may paraphrase:
    An omniscient being "knowing an event" does not force that event to come to pass. There is no cause-effect relationship - at least, not in the direction that interferes with free will.
    Last edited: Sep 26, 2006
  10. Sep 27, 2006 #9
    I think you have answered your own question. Your claim was that ability to see future events leads to a contradiction with free will, which is in fact not necessarily the case.

    (I agree, I didn’t mean to pick on your statement specifically – quite a few posts within this thread seem to make the same logical error)


    Best Regards
  11. Sep 27, 2006 #10


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    Well, my claim was actually that, regardless of the apparent paradox, invokation of an omniscient being is unnecessary, and serves simply to confuse/derail the issue. I was simply trying to clarify the initial claim.
  12. Sep 27, 2006 #11
    I don't think so. That's sort of redefining onmiscience by putting God's knowledge in storage. The complete knowledge of all possible choices and experiences is there - if God wants it. :smile:

    If this complete knowledge is potentially available, the knowledge itself must be based on potential experiences. The moment God accesses this knowledge, all these potential experiences have to be real experiences - otherwise ominscience falls into question. If God's knowledge of the possible is to be as complete as God's knowledge of the actual, then the difference between a possible experience and an actual one falls into question.

    If, in the entire history of the universe, certain experiences were denied because free will was excercised, then no being has had these experiences. If they have not been had, they can't be known with the same vividity as if they were had.

    I stand by the following assessment:

    Omniscience requires all experiences to known in full - exit free will.
    Free will requires some experiences to be denied - exit omnisicence.

  13. Sep 27, 2006 #12
    Doesn't logically follow.

    "necessarily, God knows that I do X" does not equate to "I do X necessarily" (the logical transfer of necessity fails)

    (full explanation here http://www.sfu.ca/philosophy/swartz/freewill1.htm#ldeterminism)

    I understand why you think that God's foreknowledge somehow "fixes" the future, because that is the commonly held intuitive response (and I thought the same once). But by using a strictly logical argument we can show that this is in fact not the case.

    In order to correctly claim logical transfer of necessity in the form you require, you would need to assume at least a couple of additional premises, namely (1) that God exists temporally and not atemporally and (2) some principle akin to "the principle of the necessity of the past" (see the Stanford link here http://plato.stanford.edu/entries/free-will-foreknowledge/)

    Theologians and others might claim that either or both of these premises is false (Boethius claimed (1) is false; Alvin Plantinga claims (2) is false).

    (Of course, none of this implies that free will is a coherent notion anyway - which it's not!)

    Best Regards
  14. Sep 27, 2006 #13


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    one of my problems with an omniscient being is that I believe everything that exists, exists physically. I think, to be omniscient, something would have to be larger than the universe, because it has to be able to compute (from stored knowledge) or (even more ludicrous) already have the knowledge stored of what's going to happen.

    If we look at the universe, it's like a big supercomputer, processing. It would take an even bigger supercomputer to compute the outcome of the universe, since it couldn't possibly contain all the information without at least containing a 'model' of every atom in the universe with its initial conditions.

    This is why all of our models of the universe will be generalizations or very specific cases, and not include all the cases of every possible outcome, because the one thing that can 'compute' physical reality (the universe) already requires a lot of complicated 'bits' called atoms.
  15. Sep 27, 2006 #14
    Agreed. For me there are no diffuculties with time. Pre-cognition does not equal pre-destination. Either a pre-cognitive or ex-temporal being can allow us free will, without any contradiction.

    My argument is different and can be summarised as follows:

    1) Experiences that are actually had are known in full.

    2) Experiences that are never had cannot be known in full.

    3) God knows that I do X and that I do not do Y.

    4) God knows in full all the experiences that followed from X, but cannot know in full the non-existent experiences that would have followed from Y.

    Conclusion: omniscience of both experiences requires both X and Y to happen. Free choice of X requires that Y cannot be known by any being to the same degree as X. Therefore free will and omniscience are mutually exclusive.

    Last edited: Sep 28, 2006
  16. Sep 28, 2006 #15
    Why could an omniscient god not exist in some higher dimension, such that he/she is able to observe the entirety of our 4D spacetime as a single "unity" (a single observation from that god's perspective)? Such a god would correspond to Boethius's idea of an atemporal god, able to know the entire past and future of our 4D world, but entailing no contradiction with our notion of free will.

    Best Regards
  17. Sep 28, 2006 #16
    I would challenge premise (2) (and hence also (4) and your conclusion) - By some definitions of omniscience, an omniscient being knows everything (hence not only what physically happens, but also what might have happened, what is logically possible), therefore an omniscient being knows not only the experiences you have, but also the ones you do not have but could have had (if you had chosen differently).

    Best Regards
  18. Sep 28, 2006 #17
    I completely concur with your definition of omnisicience - which includes everything that might have happened as well as everything that actually happens.

    Indeed, if omniscience referred only to what happens, then there is no contradiction with free will.

    The question now becomes: is it logically possible for any being to have full knowledge of experiences that have never been had?

    If God is everywhere and can share our consciousness, all our experiences can be fully known to God. What about those experiences we avoided by free will? Since they never got experienced, God cannot share them or know them in the same way that he knows the experiences we did have.

    To say that a being knows absolutely every detail of an experience with nothing left out amounts to saying the experience happened. If some experiences are denied through free will, then they are not experienced at all. The full details of those experiences with nothing left out must remain unknowable unless they are experienced.

    I would conlude that full omniscience - as you've defined it - can exist if, and only if, every experience that is possible is actually experienced. Exit free will.

    Since free will automatically requires some experiences never to be had, the full detail and knowledge of those experiences - with nothing left out - is simply not there. Exit omniscience.

    Omniscience and Free Will - it seems one of them has to go for the other to be logically possible.
    Last edited: Sep 28, 2006
  19. Sep 28, 2006 #18
    How do you know that an omniscient being cannot know the experiences that we do not have, in the same way that they would know the experiences that we do have? That such a thing is not possible would seem to be an assumption on your part, but is not necessarily true (indeed such an assumption would seem to put epistemological "limits" on omniscience, which is not what omniscience is all about).

    To say that a possible experience is not actually experienced by the agent making the choice is not the same as saying that the same experience cannot be known logically by the omniscient being. The omniscient being could logically know what that experience would have been like had the agent made the choice, even though the agent did not in fact make the choice.

    And I would conclude that omniscience does not require that every possible experience is "actually experienced" by an agent, only that the omniscient being has the ability to know what that experience would have been like had it actually happened.

    I see no reason why an omniscient being could not in principle know the full details of all logically possible experiences, regardless of whether those possible experience are actually "had" by some agent or not.

    I don't think so.

    What your argument essentially boils down to is a simple argument against the logical possibility of omniscience :

    (1) Definition : Omniscience entails that an omniscient being knows all details of experiences, both experiences that "have been experienced", and experiences that "have not been experienced"
    (2) Premise : (according to you) experiences which "have not been experienced" cannot be known by any being in the same detail that experiences which "have been experienced" can be known.
    (3) Hence (from 1 and 2), no being is omniscient.

    But I would challenge the logical necessity of the premise that experiences which "have not been experienced" cannot be known by any being in the same detail that experiences which "have been experienced" can be known.

    Best Regards
    Last edited: Sep 28, 2006
  20. Sep 28, 2006 #19


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    What if your omniscient being is simply capable of observing all states of QM's many worlds?

    You take an action, you do not take an action. OB sees a split in the universe. He still observes both actions, yet your free will is not violated. All that's happening by your action or inaction is that you are determining which "you" - in which universe - is the you that is asking the question.
  21. Oct 2, 2006 #20
    I would put the logic the other way around:

    The non-existence of the supernatural would imply that you have no free-will, since free-will is by definition supernatural.

    (By supernatural, I am meaning anything which cannot in principle be explained by physics.)
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