The Block Universe and The Flow of Time

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Re: The Block Universe and The Flow of Time

Postby davidm on June 13th, 2020, 10:29 am 

How can he be wrong under presentism?


He can be wrong under presentism because there is no reason to think that true propositions are not true at all times. If someone had uttered, in the year 1360, “Trump, unfortunately, will be elected in 2020,” even if he said those words under duress, even if did not know what the words meant, as he would not have known that long ago, did he not speak truly? I think he did. Even under presentism, there must be true statements about all future events, even if we do not know what those statements are. If I say today that tomorrow it will rain, and then tomorrow it rains, did I not speak truly? I did. And this is true regardless of whether presentism or eternalism is true.

If it is true today that a sea battle will take place tomorrow, then all other future events are also true today; the sea battle cannot have some special ontological status. So, if all future events are already true, there can be only one possible actual world.


No, there can be only one actual world. This is where I part company with the author, though as I mentioned, it’s not of particular importance to his main thesis. In modal logic, there are possible non-actual worlds. There is, was, and always will be, a possible non-actual world at which JFK was not shot. This means that although, in the single actual world, he was shot, it remains logically possible that he was not shot: There is a possible world at which JFK was not shot.

There are also possible non-actual worlds in which donkeys talk, pigs fly, and the
Greek gods are literally real, to take three memorable examples by David K. Lewis in his book The Plurality of Worlds. This is because all of those worlds (states of affairs) are logically possible — can be conceived without bringing about a logical contradiction. As it happens, Lewis, a champion of the philosophical doctrine of extreme modalism, believes that all of these worlds — JFK undead, donkeys talking, pigs flying, the Greek gods literally real — physically exist, but just not for us. They are, however, actual to their own inhabitants, because, according to Lewis, actuality is an indexical, just like “here” and “now.”
Most ordinary people are probably presentists, so they would say 'decide' or 'determine' rather than ‘change’.


Right, they would say that, because they are presentists. But this is my point. If they become aware of eternalism, they think that because the future is as fixed as the past, they have no free will. Why? Because they think the block universe robs them of the ability to determine the future, so that, to recover free will, they would have to be able to change the fixed future. But they don’t have to change anything — can’t change anything, under either presentism or eternalism. It is they themselves who, within the limits of their power, determine even a fixed future. Most events, of course, are beyond our control. Those within are control are said to be freely willed. The point is that even under eternalism, the fixed future is fixed in part by our free acts, in the exact same way it would be under presentism. So, yes, even in a block universe, we determine, in part, the future.

As to why we have the illusion of time “passing,” it has to be first stressed that things are definitely different from moment to moment, although, under eternalism, time does not “pass.” I think Sabine Hossenfelder has a good take on this; I linked her blog post discussing this topic way up thread. Basically, what we call the “now” represents our stored memories of the past. Hence, every “now” seems special because each “now” contain more accumulated memories. Although the future exists under eternalism, we have no memory of it because of the arrow of time, which can be conceived as compatible with both eternalism and presentism. I would recommend her post that I linked earlier for her full take on the matter.
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Re: The Block Universe and The Flow of Time

Postby Positor on June 14th, 2020, 1:01 am 

davidm » June 13th, 2020, 3:29 pm wrote:If I say today that tomorrow it will rain, and then tomorrow it rains, did I not speak truly? I did.

Suppose I say today:
(a) It will rain tomorrow.
(b) Perhaps it will not rain tomorrow.

Under presentism, it seems that (b) is true whatever happens tomorrow, because the future is open at the time of speaking. But (a) contradicts (b): if it will rain tomorrow, then it cannot be the case that it will not rain tomorrow. So if (b) is true, (a) cannot be true, even if it does rain tomorrow. If it rains tomorrow, I still spoke truly when I said that perhaps it would not do so (because of presentism). How could I have also spoken truly when I made the incompatible statement that it would (i.e. definitely) rain?

How can we resolve this apparent paradox? Is there some ambiguity in the word "will" in (a)? In addition to its role in referring to the future, does the word also carry an implication of certainty – which would be unwarranted under presentism?
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Re: The Block Universe and The Flow of Time

Postby curiosity on June 14th, 2020, 8:35 pm 

“If”... (Please note that I emphasise If.) as I believe; What we think of as the flow of time, has no preferred direction. (relative to the singular event.) Does that mean time as we think of it really is an illusion? If space expands then time must surely follow suit expanding proportionately. (resulting in entropy.) Whereas if space were to contract, time would once again need to do the same and also contract. I don’t believe if such an event occurred, that it would have any effect on the flow of time, it would simply mean that time was progressing toward the singular event , rather than away from it. ( However, it would certainly reverse entropy.)

Bye the way... There is no prize being offered for guessing that I am a proponent of bounce cosmology and If I have confused anyone by using the term singular event, (rather than singularity) its because the big bang as its misleadingly known “was” an event, whereas The nature of the proposed singularity Is pure hypothesis (Singular in this context, meaning strange, unknown and possibly unknowable. )

I must admit that I'm rather enjoying the arguments in this thread, even though I'm now more confused than ever about the concept of a block universe. Please keep the posts coming, your views make interesting reading.
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Re: The Block Universe and The Flow of Time

Postby charon on June 15th, 2020, 4:24 am 

I don't think anyone here's interested in the universe, I think they're interested in theories about the universe, which isn't quite the same thing.
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Re: The Block Universe and The Flow of Time

Postby curiosity on June 17th, 2020, 6:56 am 

I don't think anyone here's interested in the universe, I think they're interested in theories about the universe, which isn't quite the same thing.


Really ??? How strange! Is there actually any point in discussing the possible effects spacetime could have on our reality,when its unclear what space-time actually is ? I enjoy hearing/reading about other peoples thoughts on space-time, as differing viewpoints can sometimes reveal points I might have overlooked in my own efforts to gain an understanding of reality. However, at present any discussion concerning the effects of space-time on reality, (As in the block universe model.) is akin to attempting to run before learning how to walk.

I'm certainly not one of those who tries to belittle philosophers, but philosophers must always try to avoid getting too far ahead of cannon science, in order to avoid their arguments becoming farcical.

"Just my thoughts on the subject !"
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Re: The Block Universe and The Flow of Time

Postby charon on July 15th, 2020, 4:18 am 

...
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