David Albert and Barry Loewer have proposed a new interpretation of quantum mechanics which they call the Many Minds interpretation, according to which there are infinitely many minds associated with a given (physical) state of a brain. This interpretation is related to the family of many worlds interpretations insofar as it assumes strictly unitary (Schrödinger) time-evolution of quantum-mechanical systems (no reduction of the wave-packet). The Many Minds interpretation itself is principally motivated by an argument which purports to show that the (...) assumption of unitary evolution, along with some common sense assumptions about mental states (specifically, beliefs) leads to a certain nonphysicalism, in which there is a many-to-one correspondence between minds and brains. In this paper, I critically examine this motivating argument, and show that it depends on a mistaken assumption regarding the correspondence between projection operators and yes/no questions. (shrink)

State-reduction and the notion of actuality are compared to passage through time and the notion of the present; already in classical relativity the latter give rise to difficulties. The solution proposed here is to treat both tense and value-definiteness as relational properties or facts as relations; likewise the notions of change and probability. In both cases essential characteristics are absent: temporal relations are tenselessly true; probabilistic relations are deterministically true. The basic ideas go back to Everett, although the technical development (...) makes use of the decoherent histories theory of Griffiths, Omnès, and Gell-Mann and Hartle. Alternative interpretations of the decoherent histories framework are also considered. (shrink)

Abstract An argument originated by Brandon Carter presents humankind's imminent extinction as likelier than we should otherwise have judged. We ought to be reluctant to think ourselves among the earliest 0.01 %, for instance, of all humans who will ever have lived; yet we should be in that tiny group if the human race survived long, even at just its present size. While such reasoning attracts many criticisms, perhaps the only grave one is that indeterminism means there is not yet (...) any firm, theoretically predictable fact of how long the human race will survive. This, though, might not save Everett's many?worlds theory from a variant on Carter's point. Everett seemingly pictures observers as splitting into ever more versions, which explains away all apparent indeterminism; but then, absurdly, all except a vanishingly tiny proportion of one's versions would come into existence near one's death, outweighing all apparent evidence that death was not imminent. The need to avoid such a result severely constrains Everett?type theories. We need theories in which observer?versions diverge without increasing their numbers in any straightforward way. (shrink)

A case for the project of excising of confusion and obfuscation in the contemporary quantum theory initiated and promoted by David Deutsch has been made. It has been argued that at least some theoretical entities which are conventionally labelled as “interpretations” of quantum mechanics are in fact full-blooded physical theories in their own right, and as such are falsifiable, at least in principle. The most pertinent case is the one of the so-called “Many-Worlds Interpretation” (MWI) of Everett and others. This (...) set of idea differs from other “interpretations” since it does not accept reality of the collapse of Schrödinger’s wavefunction. A survey of several important proposals for discrimination between quantum theories with and without wavefunction collapse appearing from time to time in the literature has been made, and the possibilities discussed in the framework of a wider taxonomy. (shrink)