[net.religion] Foreknowledge => Determinism, no free will

donald (04/12/83)

Well, down to the crux of the matter.  I think I can get Ralph to accept my
viewpoint if I can get across my conception of free will and determinism.

Ralph doesn't think that god's foreknowledge implies determinism.

Perfect foreknowledge DOES imply determinism.  If God KNOWS about the future,
there must be a future out there for him to know!  He knows with absolute
certainty what's gonna happen.  Dress the argument up in fancy logical terms:

Defn: *Determinism* in a system S means THERE EXISTS A SPECIFICATION OF
      ALL STATES of S over all time.  i.e. there exists a function f
      mapping times to states, such that f(t) is the state of S at time t.

Defn: An *event* E in system S is a pair (U,t) where U is a state of S and
      t is a time.  E is said to have *occurred* if in fact at time t, the
      state of S is U.

Defn: *(perfect)foreknowledge* of an event E in system S means knowledge
      that event E will or will not occur in S, i.e. if E=(U,t), we
      know if at time t, the state of S is U or not.

Theorem:  Perfect foreknowledge of all events in S in implies
      determinism in S.
Proof:
      Assume we have perfect foreknowledge of all events in system.
      Let S be any system, e.g. the Universe.  Take all possible events
      (U,t).  We know which events will actually happen by foreknowledge
      hypothesis, so for any given time t we can pick out of all the
      possible corresponding states the one that will actually occur.
      But if we do that for all times, we've just specified a function
      mapping times to states such that f(t) is the state of S at time
      t.  By the first definition, S is determined.

Do you believe that!?  If god knows the future, we're all puppets.

    Suppose you know a person very well. In fact you know him/her so well, that
    in various situations you can know or predict with incredible accuracy what
    he/she will think or how he/she will respond...  given such a situation, are
    you compelled to say that the object of the knownness is deterministic?
    I think not. You could, of course, but I think it just as plausible to say
    that the person nevertheless chose, and thus excersised free will. What
    occurred is that you knew WHAT he/she would choose.

What do you mean by "free will"?  It seems your definition boils down to
"if one does something then one is exercising free will", which is sort of
a null statement.

Certainly we make choices, but that hardly constitutes free will, does it?
My Pascal program makes choices every time it executes a case statement.
Our own choices just happen to be more complicated.
If my Pascal program is soooo complicated and bug-ridden that you can't
tell what it will do on every input, are you going to say that it has
free will too?

I think TRUE free will means that something is ultimately UNPREDICTABLE.
The latter is not allowed by an omniscient god.

    To draw it out a little, suppose you know what he is going to do for
    the next twentyfour hours. Does he have free will? Again you could argue
    he doesn't of course, but on the other hand one could say, yes he does!
    You may know what he is going to do, but you can't (or won't) change it!
    He chooses, and it is completely in his hands. You can't (or won't)
    take control.

If I let a ball roll down a hill without stopping it (because I can't or
won't) am I letting the ball exercise its free will?

    So what it comes down to ... is that you reject my notion of free will.
    I don't think you can say God MUST be a controller.

Yep.  I do reject your notion of free will,  because it seems to boil down
to triviality.  You're saying if we do ANYTHING then we're exercising
free will because God isn't actively interfering with us.  But as I argued
above, the very fact that God knows what we'll do means we're puppets,
albeit with the illusion of free will.

And I say that God MUST be a controller, 'cause he HIMSELF started up the whole
shebang KNOWING what was gonna happen.  If that ain't premeditated, I don't
know what is.


						Don Chan

dje (04/14/83)

Don, I don't fault your reasoning even though I disagree with your conclusions.
The difference is in our assumptions.  To you free will is illusory given
divine foreknowledge.  To me free will is real because my actions are 
predicated on my own choices rather than on God's foreknowledge.

Which set of assumptions is better?  Could it be taken as a matter of choice?
Perhaps future contributors could look into the consequences of the two
different sets of assumptions.

			Dave Ellis / Bell Labs, Piscataway NJ
			...!harpo!npoiv!npois!houxm!5941ux!dje
			...!ariel!houti!hogpc!houxm!5941ux!dje