Online research in philosophy

In this paper we describe some first steps for bringing the framework of branching space-times to bear on quantum information theory. Our main application is quantum error correction. It is shown that branching space-times offers a new perspective on quantum error correction: as a supplement to the orthodox slogan, ``fight entanglement with entanglement'', we offer the new slogan, ``fight indeterminism with indeterminism''.

This paper proposes a reconciliation between libertarian freedomand causal indeterminism, without relying on agent-causation asa primitive notion. I closely examine Peter van Inwagen''s recentcase for free will mysterianism, which is based in part on thewidespread worry that undetermined acts are too chancy to befree. I distinguish three senses of the term chance I thenargue that van Inwagen''s case for free will mystrianism fails,since there is no single construal of the term change on whichall of the premises of his argument for free will–causalindeterminism incompatibilism are true. By use of a particularevent-causal indeterminist account of free action, I support thecase for free will–indeterminism compatibilism.

In this paper I argue that Robert Kane’s defense of event-causal libertarianism, as presented in Responsibility, Luck, and Chance: Reflections on Free Will and Indeterminism, fails because his event-causal reconstruction is incoherent. I focus on the notions of efforts and self-forming actions essential to his defense.

Two initially different arguments for indeterminism are often based either upon the Uncertainty Relations or the statistical interpretation of the wave equation of quantum mechanics. Both arguments ultimately involve three factors: (1) the assumption that elementary entities are enough like classical particles for it to make sense to say they are either determined or indetermined, (2) the fact that no exact measurements are possible of quantities supposed to characterize elementary entities, (3) the pragmatic supposition that determinism is false unless exact predictions are theoretically possible. If it is legitimate to use (3) to prove indeterminism, then an equally legitimate argument can be based upon (2) which denies (1). Thus, it is doubtful that quantum mechanics supports indeterminism, though it may show that the concepts of 'determined' and 'indetermined' are inapplicable to the world.

It is argued that seemingly “merely technical” issues about the existence and uniqueness of self-adjoint extensions of symmetric operators in quantum mechanics have interesting implications for foundations problems in classical and quantum physics. For example, pursuing these technical issues reveals a sense in which quantum mechanics can cure some of the forms of indeterminism that crop up in classical mechanics; and at the same time it reveals the possibility of a form of indeterminism in quantum mechanics that is quite distinct from the indeterminism of state vector collapse. More generally, the examples considered indicate that the classical–quantum correspondence is more intricate and delicate than is generally appreciated. The aim of the article is to give a series of examples that reveal why the technical issues about self-adjointness are relevant to the philosophy of science and that help to make the issues accessible to philosophers of science.

I examine different arguments that could be used to establish indeterminism of neurological processes. Even though scenarios where single events at the molecular level make the difference in the outcome of such processes are realistic, this falls short of establishing indeterminism, because it is not clear that these molecular events are subject to quantum mechanical uncertainty. Furthermore, attempts to argue for indeterminism autonomously (i.e., independently of quantum mechanics) fail, because both deterministic and indeterministic models can account for the empirically observed behavior of ion channels.

Our discussion in the first five sections shows that little new can be said about compatibilism, that van Inwagen's argument for incompatibilism still stands, and that the view of free agency for a libertarian has little chance unless she believes that agency contains elements that are not within the natural order. Borrowing from a suggestion from Russell we expanded the Nozick-Kane model of libertarian free agency and connected it to the Wignerian interpretation of quantum measurement. As such, free decisions and choices may well violate the Born rule of probability distribution and yet it is shown how such violations are unlikely to be detected in experiments. This model is probably the only model in which Loewer's van Inwagen style argument for the incompatibility between free agency and quantum indeterminism does not apply, and it is a model in which free agency is not only compatible but necessary. It is compatible with indeterminism and it is necessary for the determinateness of any measurement outcomes.