Is the future inevitable?

This strikes me as a misunderstanding of what chaos is. Chaotic systems are unpredictable because of their sensitive dependence on initial conditions. So, if the other universe was identical in almost everything, the chaotic nature of reality would probably lead them to nevertheless diverge signifcantly over time.If they really were exact duplicates, as YellowJay asked, then it wouldn't matter how chaotic they were, they would evolve identically. Chaotic systems are wholly deterministic. Their apparent randomness is only a reflection of their complexity. If we understood the rules which governed them perfectly, and the exact value of every relevant variable, we would be able to predict outcomes precisely.Now, if the world is really probabilistic on a quantum level you may be right, since this could be a genuinely random element, but I've never been able to get my head around quantum physics.Edited by caffeine, : tags

Not necessarily. It's possible to make certain small changes to a chaotic system without altering the outcome at all. A slightly different small change, however, could have dramatic effects, but it is theoretically possible to have two slightly different universes which are indistinguishable (once again, I'm ignoring quantumness (quantumity?)).Edited by caffeine, : No reason given.

The number of variables is of no relevance to the question of determinism. If there are billions upon billions of variables to consider, the result would still be predetermined if the processes that decide those variables and the way they interact are deterministic. All that matters is whether the world actually is deterministic at a basic level, and if it's not then the result is no predetermined, regardless of whether there are a billion relevant variables or only one,

How? If you mean it makes prediction difficult, then no argument, but it has no bearing whatsoever on whether or not the universe is deterministic, as you just agreed.

Would you prefer 'conguent' to 'identical'? Wasn't all the talk of quantum physics and hidden variables supposed to demonstrate that they would, because particles behave non-deterministically at a quantum level?

It has been asserted; it has not been shown. I find these experiments unconvincing of anything, as the idea that we're able to report the moment at which we decide to act with accuracy measured in fractions of seconds is absurd. I suspect that the conclusion is right, but don't see how this experiment is supposed to demonstrate it.

I've been trying to read some about Bell's theorem, and whilst I'm a bit confused it seems that it doesn't. What it is supposed to prove is that there can be no undiscovered local variables. If, however, your extra variables allow an event somewhere to have a causal effect somewhere else in less time than you could travel between the two at the speed of light, then such an undiscovered variable is not disproven. It has been suggested, for example, that information could be passed through higher dimensions in which two points are close to one another, despite being distantly separated in normal space.I'm struggling to grasp this, so I may have badly mangled the above!

I'm not sure this is any more convincing. Let's consider what they're actually demonstrating here. Someone was told to do something as soon as they'd decided which of two things to do and when. Retroactively analysed, we can see that certain sorts of brain activity beginning up to 7 seconds before the did the thing predict the outcome.Fantastic. How is that brain activity supposed to be distinguished from 'beginning to make a willful decision'? There's no requirement that the timelag between beginning to make a conscious decision and completing it be less than 7 seconds, is there?Edited by caffeine, : No reason given.

But to get back to some highschool philosophy, there's two options available:1. Your actions are predictable based on past events, and therefore pre-determined, which you consider incompatible with free will.2. Your actions are not predictable based on past events, and therefore random and arbitrary. Random behaviour means living by the flip of a metaphorical coin - there's still no room for free will.

That's not really a coherent sentence. You'll have to elaborate on how something can be neither predictable nor arbitrary, because I don't see any alternative.