rationalskepticism.org

GrahamH wrote:

John Platko wrote:

GrahamH wrote:

John Platko wrote:
No, in this case it depends entirely on what must be done to predict the - Oh heck, here's how Deutsch puts it:

‘which box to open’; in the case of the quantum version, instead, the variable ‘which box to open’ is not sharp.

The scenario says nothing about a simulation of T. That is Deutch's invention. Just one way we might predict T, but not the only one, as I set out previously. Also, a predictor need not be 'an instance of T'. It only need be a predictor of T.

Yes, this is Deutsch's invention. He's trying to make a point about free will and why the unpredictability of a QM measurement is fundamentally different than the unpredictability of the creation of knowledge.

Deutsch's argument does seem to depend on the idea that the one and only way to predict T is to simulate it; he says above: "this choice unpredictable, in the sense that the only way to predict it is to bring about a simulation of T". As both GrahamH and you have been pointing out, there are usually other available ways of predicting things.

At the moment, the only available way to predict other humans in real time does involve simulating them, using our own very similar brains, so I think we still have free will for practical purposes: the simulations are far from perfect and even if they were, something like Deutsch's argument could hold. This could end if scientists become able to predict brains more effectively by other means, but so far that's not close to happening.