Orthodox neural materialists think mental states are neural events or orthodox material properties of neutral events. Orthodox material properties are defining properties of the “physical”. A “defining property” of the physical is a type of property that provides a necessary condition for something’s being correctly termed “physical”. In this paper I give an argument against orthodox neural materialism. If successful, the argument would show at least some properties of some mental states are not orthodox material properties of neural events. I (...) argue against the existence of a posteriori identities. (shrink)

This is a detailed defense of the view that identity is not an eternal, necessary relation: things can be identical at one time and distinct at another; they can be identical in one world and distinct in another. The defense is judicial rather than passionate, as Gallois’s primary goal is to persuade the reader that the view is ‘at least as credible’ as its more fashionable alternatives. But Gallois also aims to show that if the view is credible then it (...) provides a better solution to a wide range of identity puzzles (the ship of Theseus, the problem of material constitution, the puzzle of amoebic fission, and the like). As it turns out, Gallois goes a long way towards establishing the truth of this conditional claim. The real issue, however, is the credibility of the view itself, and in spite of the many sophisticated and original arguments that fill the pages of the book I suspect that many readers will not change their skeptical minds. (shrink)

A new theory of identity statements is put forward which appeals to a basic distinction between two notions of identity, i.e. strict and loose identity. The former is the traditional necessary relation of an object with the object itself, whereas the latter is a contingent relation of reduction of some (at least two) possible unactual objects to a possible actual object. By appealing to strict identity, one can maintain that some tokenings of identity sentences express a semantic content which is (...) both knowable apriori only and a necessary proposition. By appealing to loose identity instead, one can maintain that other tokenings of identity sentences express a semantic content which is both knowable a posteriori only and a contingent proposition. (shrink)

Faced with strong arguments to the effect that Leibniz''sPrinciple of the Identity of Indiscernibles (PII) is not a necessary truth, many supporters of the Principle have staged a strategic retreat to the claim that it is contingently true in this, the actual, world. The purpose of this paper is to examine the status of the various forms of PII in both classical and quantum physics, and it is concluded that this latter view is at best doubtful, at worst, simply wrong.

Department of History and Philosophy of Science. University of Cambridge, Free School Lane, Cambridge CB2 3RH This paper is concerned with the question of whether atomic particles of the same species, i. e. with the same intrinsic state-independent properties of mass, spin, electric charge, etc, violate the Leibnizian Principle of the Identity of Indiscernibles, in the sense that, while there is more than one of them, their state-dependent properties may also all be the same. The answer depends on what exactly (...) the state-dependent properties of atomic particles are taken to be. On the plausible interpretation that these should comprise all monadic and relational properties that can be expressed in terms of physical magnitudes associated with self-adjoint operators that can be defined for the individual particles, then the weakest form of the Principle is shown to be violated for bosons, fermions and higher-order paraparticles, treated in first quantization *Some of the arguments inn this paper appeared in a thesis submited by one of us (S.F.) In partial fulfilment of the requirements for the PhD degree of the University of London, in 1984. entitled 'Identity and ‘Individuality in Classical and Quantum Physics’. (shrink)

Putative counterexamples to the Principle of Identity of Indiscernibles (PII) are notoriously inconclusive. I establish ground rules for debate in this area, offer a new response to such counterexamples for friends of the PII, but then argue that no response is entirely satisfactory. Finally, I undermine some positive arguments for PII.