Lennart Nilsson wrote:

What on earth does the following footnote mean? Are we back to
where the "quantumbuck" stops?

Understanding Deutsch's Probability in a Deterministic Multiverse by

Footnote 16
The following objection is sometimes raised against the
approach: in an Everettian context, all outcomes of a decision are
and therefore it simply does not make sense to make choices, or to
about how one should act. If that is correct, then while we may agree
probability can in principle be derived from rationality, this is of
no use
to the Everettian, since (it is claimed) the Everettian cannot make
sense of
rationality itself.
If this was correct, it would be a pressing 'incoherence problem' for
decision-theoretic approach. The objection, however, is simply
mistaken. The
mistake arises from an assumption that decisions must be modelled as
Everettian branching, with each possible outcome of the decision
realized on
some branch. This is not true, and it is not at all what is going on
in the
decision scenarios Deutsch and Wallace consider.
Rather, the agent is making a genuine choice between quantum games,
only one
of which will be realized (namely, the chosen game). To be sure, each
consists of an array of branches, all of which will, if that game is
be realized. But this does not mean that all games will be realized.
It is
no less coherent for an Everettian to have a preference ordering over
quantum games than it is for an agent in a state of classical
uncertainty to
have a preference ordering over classical lotteries.

To me this looks like an attempt to hold onto rationality and meaning, which requires genuine choice. Modern man has been stripped of his/her rationality as a result of trying to hold onto rationalism in a closed system. But like I've said on my soapbox before, the multiverse doesn't solve this problem, it just makes it worse if anything. Actually, if we truly accept the conclusions of rationalism in a closed system, the multiverse doesn't make it worse; but it also doesn't help one iota, contrary to the hopes of its proponents.

Tom Caylor

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