There has been considerable recent interest in the consequences of closed timelike curves (CTCs) for the dynamics of quantum mechanical systems. A vast majority of research into this area makes use of the dynamical equations developed by Deutsch, which were developed from a consistency condition that assumes that mixed quantum states uniquely describe the physical state of a system. We criticize this choice of consistency condition from an epistemic perspective, i.e., a perspective in which the quantum state represents a state (...) of knowledge about a system. We demonstrate that directly applying Deutsch’s condition when mixed states are treated as representing an observer’s knowledge of a system can conceal time travel paradoxes from the observer, rather than resolving them. To shed further light on the appropriate dynamics for quantum systems traversing CTCs, we make use of a toy epistemic theory with a strictly classical ontology due to Spekkens and show that, in contrast to the results of Deutsch, many of the traditional paradoxical effects of time travel are present. (shrink)
The thesis of this article is that an attitude akin to pragmatism is internal to the scientific enterprise itself, and as a result many scientists will make the same types of non-essentialistic interpretations of their subject matter that are made by pragmatists. This is demonstrably true with respect to those scientists who study the biological basis of emotion such as Panksepp, LeDoux, and Damasio. Even though these scientists are also influenced by what cognitive psychologists call the essentialist bias, their research (...) programs are coherent with Peter Zachar?s rejection of natural kinds in favor of practical kinds. When the confrontation with complexity leads a scientist to offer non-essentialist interpretations, two popular options are to go eliminativist or go nominalist. Pragmatists prefer the nominalistic option, and we provide reasons for suggesting that scientists should as well. (shrink)
The Conservative government made appraisal compulsory to monitor teaching more effectively. Unable to elicit the type of data required, the process became marginalised. Labour is now turning to appraisal to raise standards. Though appearing more conciliatory, it is argued that the end result will be to achieve the Conservatives' original aim of controlling teachers.
Philosophers have not resisted temptation to transgress against the logic of their own conceptual structures. Self-undermining position-taking is an occupational hazard. Philosophy stands in need of conceptual therapy.The author describes three conceptions of philosophy: the narcissistic, disputatious, and therapeutic. (i) Narcissistic philosophy is hermetic, believing itself to contain all evidence that can possibly be relevant to it. Philosophy undertaken in this spirit has led to defensive, monadically isolated positions. (ii) Disputatious philosophies are fundamentally question-begging, animated by assumptions that philosophical adversaries (...) reject. (iii) The intention of therapeutic philosophy is to study philosophical positions from the standpoint of their internal consistency, or lack of it. In particular, its interest is in positions that either compel assent, because they cannot be rejected without self-referential inconsistency, or self-destruct because self-referential inconsistency cannot be avoided. The article's focus is on the latter. Several examples of self-undermining positions are drawn from the history of philosophy, exemplifying two main varieties of self-referential inconsistency: pragmatical and projective. (shrink)