(urth) 5HC : Skinner, Turing, Laplace
rasputin_ at hotmail.com
Mon Feb 21 11:44:28 PST 2005
I mean that you unwittingly included factors (demon outside the universe
with ability to interact with things inside the universe) that may not *say*
in so many words that "the universe is not deterministic", but nonetheless
logically entail that it *cannot be* deterministic. Left as is, the problem
collapses to nonsense because by its definition it is, but cannot be,
deterministic. Remedies (such as they are):
Drop the stipulation that the universe be deterministic. This would remove
the demon's means of predicting the future, which is no good for the
purposes of the thought problem.
Keep the demon outside the universe but close the system. Now the universe
can be deterministic, the demon can predict things in it, but can no longer
tell you about those predictions. This too is not useful for the thought
The above two sort of reduce things to where no problem really exists any
more. The third brings in a whole new problem:
Bring the demon inside the universe and close the system. Now he can make
predictions, and tell them to you. But these predictions require a full
knowledge of the state of the universe - which now includes himself. The
demon must "know" the disposition of his own brain states - he must know the
totality of what he knows. So for each item X in his knowledge, the fact
that he knows X requires him to know (that he knows X), and this in turn
requires him to know (that he knows (that he knows X)), and so on in an
infinite regress. This isn't just a trivial abstraction. The problem is
analogous to the problem I mentioned of making a precise map of the
universe. If the map is inside the universe, then it must include itself,
which must include itself, which must include itself.
[A curious aside... An abstract but almost entirely meaningless possible
solution to the map problem is to simply call the universe a scale map of
itself. This requires a somewhat... flexible... concept of "representation".
If you were George Berkeley you might apply such a solution and say that the
universe *is* the demon's mind. But such a demon would no longer be
Laplace's, it would not be predicting anything, it would be making the
future (and all of being) by thinking it. But in any event, this wanders
just a bit off from the purpose of the thought problem.]
>I'm afraid I'm simply not following you here: what do you mean by
>>Even if you carefully specify that it's completely deterministic, the
>>"careless" aspect stipulates just as firmly that it can't be
>>deterministic. Because the demon is outside the system, he can't interact
>>with it if it's a closed system. If he can interact with it, then you have
>>influences outside the universe affecting causality within the universe,
>>and it's not deterministic.
>>If you extend your system to include the demon's interaction, then you've
>>effectively placed the demon inside the horizon of your system/universe,
>>and thus you get the other problem.
>>>The way I see it, he is outside your effective universe.
>>>Your effective universe + Laplace's Demon & his abode = Real Universe
>>>Now, the Demon can predict the effective universe, because he is
>>>omniscient, and we've
>>>carefully specified that it is completely deterministic, the only
>>>factor is the self-same Demons deeds.
>>>However, even if omnisciene didn't suffice for the Demon to know what he
>>>will do, and
>>>what effects that will have, he knows himself! He knows what he wants
>>>or will do, and so
>>>can factor himself in, and get a final equation to solve, if you will.
>>>The problem is how to give data which will have a null effect, or will be
>>>An entirely different problem from free will.
>>>The lesson I draw is that omniscience is impossible.
>>>>There is a problem with any example that drags in Laplace's demon (well,
>>>>granted, he's meant to be problematic). Probably more than one. But
>>>>working with what you've hinted at, start by asking if the demon is
>>>>inside the universe or apart from it on some higher level? If the latter
>>>>then either he's not available for your thought problem or your universe
>>>>isn't deterministic, and if the former you run into the whole
>>>>"[W]hat everyone does not know, so that it counts as differential
>>>>knowledge, that is a glorious thing to be concerned with. What everyone
>>>>knows on the other hand, so that the difference is the trivial one of
>>>>how it is known, that is a waste of effort to be concerned about - for
>>>>one cannot possibly become self-important through knowing it."
>>>>>Laplace's demon is truly omniscience no?
>>>>>Then he knows you are going to tell me, and has factored that in.
>>>>>He will also know that you will ask for an updated prediction.
>>>>>That too will be foreseen by his omniscience right?
>>>>>Furthermore, he will see you scurrying back to tell me.
>>>>>But, omniscient being he is, he can see how many times you will be able
>>>>>upset the temporary equilibrium of my desires, and indeed, when I will
>>>>>begin to ignore
>>>>>you (or ask what you are smoking and how can I synthesize suma that?).
>>>>>That number being finite, he can easily work out what my final desires
>>>>>will be, and give the answer
>>>>>which will both start the sequence and end it.
>>>>>Even better, in a deterministic universe like this, to the Demon, the
>>>>>only unkown will be himself.
>>>>>So he can easily choose how he will perturb the universe, and make his
>>>>>predictions on that basis
>>>>>If this is an argument, seems more like one against omnisicence.
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