Locke’s thesis states that no two things of the same sort can be in the same place at the same time. The thesis has recently received extensive discussion, with some philosophers attempting to find arguments in its favour and others attempting to provide counter-examples. However, neither the arguments nor the counter-examples have been especially convincing; and it is my aim, in this short note, to present what I believe is a more convincing counter-example to the thesis.

_Identity and Discrimination_, originally published in 1990 and the first book by respected philosopher Timothy Williamson, is now reissued and updated with the inclusion of significant new material. Williamson here proposes an original and rigorous theory linking identity, a relation central to metaphysics, and indiscriminability, a relation central to epistemology.__ Updated and reissued edition of Williamson’s first publication, with the inclusion of significant new material Argues for an original cognitive account of the relation between identity and discrimination that has been (...) influential in the philosophy of perception Pioneers the use of epistemic logic to solve puzzles about indiscriminability Develops the application of techniques from mathematical logic to understand issues about identity over time and across possible worlds. (shrink)

The question 'What is the criterion of identity for directions?' might be construed as asking either 'When do lines have the same direction?' or 'When are directions identical?'. Frege's answer 'When they are parallel' fits the former question, not the latter, for it specifies a relation other than identity between lines, not directions. Jonathan Lowe thinks the latter question more fundamental, and claims that Frege's criterion can be reformulated to answer it: 'When some line with one is parallel to some (...) line with the other'. At p. 147 of Identity and Discrimination I make three points against this view: Lowe's construal does not permit a principled rejection of an intuitively unacceptable answer to the original question, On pain of circularity, Lowe's answer uses conceptual resources beyond those of Frege's, and thus is not a mere reformulation, Lowe's question seems to make the hopeless demand for something more basic than 'x = y Lowe's reply 'One-level versus two-level identity criteria' does not address or . I shall follow him in discussing only. (shrink)

This volume began as a remembrance of Alonzo Church while he was still with us and is now finally complete. It contains papers by many well-known scholars, most of whom have been directly influenced by Church's own work. Often the emphasis is on foundational issues in logic, mathematics, computation, and philosophy - as was the case with Church's contributions, now universally recognized as having been of profound fundamental significance in those areas. The volume will be of interest to logicians, computer (...) scientists, philosophers, and linguists. The contributions concern classical first-order logic, higher-order logic, non-classical theories of implication, set theories with universal sets, the logical and semantical paradoxes, the lambda-calculus, especially as it is used in computation, philosophical issues about meaning and ontology in the abstract sciences and in natural language, and much else. The material will be accessible to specialists in these areas and to advanced graduate students in the respective fields. (shrink)

Quine's areas of interest are panoramic, as this lively book amply demonstrates.

Locke thought that it was impossible for there to be two things of the same kind in the same place at the same time. I offer (what looks to me like) a counterexample to that principle, involving two ships in the same place at the same time. I then consider two ways of explaining away, and one way of denying, the apparent counterexample of Locke's principle, and I argue that none is successful. I conclude that, although the case under discussion (...) does not refute Locke's principle, it constitutes a serious challenge to it. (shrink)

I aim to show that there are cases in which an ordinary material object exists intermittently. Afterwards there are a few words about the consequences of acknowledging such cases, but what is of more interest is the route by which the conclusion is reached. When deciding among competing descriptions of the cases considered, I have tried to reduce to a minimum the role of intuitive judgment, and I have based several arguments on "metaphysical principles," two of which I have defended.

When is there no fact of the matter about a metaphysical question? When multiple candidate meanings are equally eligible, in David Lewis's sense, and fit equally well with ordinary usage. Thus given certain ontological schemes, there is no fact of the matter whether the criterion of personal identity over time is physical or psychological. But given other ontological schemes there is a fact of the matter; and there is a fact of the matter about which ontological scheme is correct.

E. J. Lowe; One-level versus two-level identity criteria, Analysis, Volume 51, Issue 4, 1 October 1991, Pages 192–194, https://doi.org/10.1093/analys/51.4.192.

This work gathers selected essays by the author in two areas of philosophy. The first 12 pieces concern the philosophy of language, and the volume is completed by four studies in Kantian metaphysics.