Online research in philosophy

Review of "Space, Time, and Stuff" by Frank Arntzenius.

From classical mechanics to quantum �field theory, the physical facts at one point in space are held to be independent of those at other points in space. I propose that we can usefully challenge this orthodoxy in order to explain otherwise puzzling correlations at both cosmological and microscopic scales.

It is argued that the components of the superposed wave function of a measuring device, each of which represents a definite measurement result, do not correspond to many worlds, one of which is our world, because all components of the wave function can be measured in our world by a serious of protective measurements, and they all exist in this world.

In this first paper we outline what possible historic-epistemological role might have played the work of Ulisse Dini on implicit function theory in formulating the structure of differentiable manifold, via the basic work of Hassler Whitney. A detailed historiographical recognition about this Dini's work has been done. Further methodological considerations are then made as regards history of mathematics.

Discussion of Alvin Plantinga's book, "Where the Conflict Really Lies".

We argue that the analysis of cognitive attitudes should play a central role in developing more sophisticated accounts of the proper roles for values in science. First, we show that the major recent efforts to delineate appropriate roles for values in science would be strengthened by making clearer distinctions among cognitive attitudes. Next, we turn to a specific example and argue that a more careful account of the distinction between the attitudes of belief and acceptance can contribute to a better (...) understanding of the proper roles for values in a case study from paleoanthropology. (shrink)

I present a local, deterministic model of the EPR-Bohm experiment, inspired by recent work by Joy Christian, that appears at first blush to be in tension with Bell-type theorems. I argue that the model ultimately fails to do what a hidden variable theory needs to do, but that it is interesting nonetheless because the way it fails helps clarify the scope and generality of Bell-type theorems. I formulate and prove a minor proposition that makes explicit how Bell-type theorems rule out (...) models of the sort I describe here. (shrink)

On the occasion of the recent experimental detection of a Higgs-type particle at the Large Hadron Collider (LHC) at CERN, the paper reviews philosophical aspects of the Higgs mechanism as the presently preferred account of the generation of particle masses in the Standard Model of elementary particle physics and its most discussed extensions. The paper serves a twofold purpose: on the one hand, it offers an introduction to the Higgs mechanism and its most interesting philosophical aspects to readers not familiar (...) with it; on the other hand, it clarifies widespread misunderstandings related to the role of gauge symmetries and their breaking in it. (shrink)

In a series of recent papers, Simon Saunders, Fred Muller and Michael Seevinck have collectively argued, against the folklore, that some non-trivial version of Leibniz's principle of the identity of indiscernibles is upheld in quantum mechanics. They argue that all particles---fermions, paraparticles, anyons, even bosons---may be weakly discerned by some physical relation. Here I show that their arguments make illegitimate appeal to non-symmetric, i.e.~permutation-non-invariant, quantities, and that therefore their conclusions do not go through. However, I show that alternative, symmetric quantities (...) may be found to do the required work. I conclude that the Saunders-Muller-Seevinck heterodoxy can be saved after all. (shrink)

This paper argues that whereas philosophical discussions of first-person methods often turn on the veridicality of first-person reports, more attention should be paid to the experimental circumstances under which the reports are generated, and to the purposes of designing such experiments. After pointing to the ‘constructedness’ of first-person reports in the science of perception, I raise questions about the criteria by which to judge whether the reports illuminate something about the nature of perception. I illustrate this point with a historical (...) debate between Gestalt psychologist and atomists, both of whom used first-person methods to investigate perception. (shrink)

Conference instructions for [2010] Philosophy of Scientific Experimentation: A Challenge to Philosophy of Science (Pittsburgh; October 15-17, 2010).

Moore’s problem or Moore’s ‘paradox’ arises from the fact that consistent propositions of the form of (1) and (2): (1) It is raining but I believe it is not raining (2) It is raining but I don’t believe it is raining strike us as being contradictory. Shoemaker explained this oddity by producing a proof that belief in such sentences is either inconsistent or self-refuting. For Sorensen many propositional attitudes have scopes smaller than the class of consistent propositions. Inaccessible consistent propositions (...) are ‘blindspots’. Moore-propositions are the blindspots of belief. According to either, Moore-propositions are unbelievable. I argue that Moore-propositions are actually believable. (shrink)

In many fields of biology, researchers explain a phenomenon by characterizing the responsible mechanism. This requires identifying the candidate mechanism, decomposing it into its parts and operations, recomposing it so as to understand how it is organized and its operations orchestrated to generate the phenomenon, and situating it in its environment. Mechanistic researchers have developed sophisticated tools for decomposing mechanisms but new approaches, including modeling, are increasingly being invoked to recompose mechanisms when they involve nonsequential organization of nonlinear operations. The (...) results often are dynamical mechanistic explanations. The steps in mechanistic research are illustrated using research on circadian rhythms. (shrink)

An evolutionary basis for Bayesian rationality is suggested, by consid- ering how natural selection would operate on an organism's `policy' for choosing an action depending on an environmental signal. It is shown that the evolutionarily optimal policy, as judged by the criterion of maximal expected reproductive output, is the policy which for each signal, chooses an action that maximizes conditional expected output given that signal. An organism using such a policy is behaving as if it were a Bayesian agent with (...) probabilistic beliefs about the states of nature, that it updates by conditionalization, and whose choice behaviour obeys expected util- ity maximization. This suggests a possible route by which Bayes-rational creatures might have evolved. (shrink)

It is argued that the existence of a minimum interval of space and time may imply the existence of gravity as a geometric property of spacetime described by general relativity.

The question of observability of sign changes under 2pi rotations is considered. It is shown that in certain circumstances there are observable consequences of such sign changes in classical physics. A macroscopic experiment is proposed which could in principle detect the 4pi periodicity of rotations.

In this paper, I argue that the conceptual changes that occurred in the structure of physical knowledge during the second half of the 19th century, are reflected by the concept of the “primary ideal object” (PIO) and its implicit definition within appropriate systems of statements, called a “nucleus of a branch of physics” (NBP). Within an NBP focus shifts away from discovering “laws of nature” to observations of a physical object (system) and its states, while the distinct notion of “measurable” (...) replaces the vague notion “observable”. On the basis of this notion, the roles of physical models and measurements within physics, different kinds of work, experiments, and laws are discussed. Next follows a discussion of different levels of change in science, after which this distinction is compared to Kuhn’s model. Finally, I present a new combination of “realism” and “constructivism”, which differs from both the “constructive empiricism” of van Fraassen and from different “empirical realisms”. (shrink)

Lewis et al. recently demonstrated that additional assumptions such as preparation independence are always necessary to rule out a psi-epistemic model, in which the quantum state is not uniquely determined by the underlying physical state. Here we point out that these authors ignored the important work of Aharonov, Anandan and Vaidman on protective measurements, and their conclusion, which is based only on an analysis of conventional projective measurements, is not true.

To claim that x was the cause of y (or x caused y) is 1) to assume that x was one of a number of things, each of which together with the others was sufficient to have brought about y, and 2) to deem x responsible for the occurrence of y. A best-explanation argument, including application to cases, is offered in defense of this analysis, which holds that claiming that something is the cause is, in part, a speech act (deeming (...) x to be responsible) that reflects the cause selector’s values or perspectives. No proposed alternative explanation accounts for all the cases with which I am familiar, but this analysis does account for them. Thus the analysis and the defense of sole singular causal claims call for more than empirical evidence, though of course evidence is very important. (shrink)

Protective measurement is a new measuring method introduced by Aharonov, Anandan and Vaidman (1993). By a protective measurement, one can measure the expectation value of an observable on a single quantum system, even if the system is initially not in an eigenstate of the measured observable. This remarkable feature of protective measurements was challenged by Uffink (1999, 2012). He argued that only observables that commute with the system's Hamiltonian can be protectively measured, and a protective measurement of an observable that (...) does not commute with the system's Hamiltonian does not actually measure the observable, but measure another related observable that commutes with the system's Hamiltonian. In this paper, we show that there are several errors in Uffink's arguments, and his alternative interpretation of protective measurements is untenable. (shrink)

It has been argued that the existence of a minimum observable interval of space and time (MOIST) is a model-independent result of the combination of quantum field theory and general relativity. In this paper, I promote this result to a fundamental postulate, called the MOIST postulate. It is argued that the postulate leads to the existence of a maximum signal speed and its invariance. This new result may have two interesting implications. On the one hand, it suggests that the MOIST (...) postulate can explain the invariance of the speed of light, and thus it might provide a deeper logical foundation for special relativity. Moreover, it suggests that the speed constant c in modern physics is not the actual speed of light in vacuum, but the ratio of the minimum observable length to the minimum observable time interval. On the other hand, the result also suggests that the existing experiments confirming the invariance of the speed of light already provide observational evidence to support the MOIST postulate. (shrink)

How does other people’s opinion affect judgments of norm transgressions? In our study, we used a modification of the famous Asch paradigm (1951, 1955) to examine conformity in the moral domain. The question we addressed was how peer group opinion alters normative judgments of scenarios involving violations of moral, social, and decency norms. The results indicate that even moral norms are subject to conformity, especially in situations with a high degree of social presence. Interestingly, the degree of conformity can distinguish (...) between different types of norms. (shrink)

Numerous approaches to a quantum theory of gravity posit fundamental ontologies that exclude spacetime, either partially or wholly. This situation raises deep questions about how such theories could relate to the empirical realm, since arguably only entities localized in spacetime can ever be observed. Are such entities even possible in a theory without fundamental spacetime? How might they be derived, formally speaking? Moreover, since by assumption the fundamental entities can't be smaller than the derived (since relative size is a spatiotemporal (...) notion) and so can't 'compose' them in any ordinary sense, would a formal derivation actually show the physical reality of localized entities? We address these questions via a survey of a range of theories of quantum gravity, and generally sketch how they may be answered positively. (shrink)

Discussions of the concept of disease have largely focused on whether a specific account successfully identifies necessary and sufficient conditions for a state to count as pathological. Correctly accounting for examples of pathology, however, is not the only basis for evaluating such accounts. Here, I argue that we should expect any understanding of health and disease to be consistent with important aspects of medical practice. Specifically, any such understanding should be consistent with the ways that we attempt to treat and (...) cure. What we do when we treat must be intelligible in terms of reducing or eliminating pathology and promoting health. If not, it is hard to understand what it is that an account of health and disease provides for us. It runs the risk of become an empty abstraction of little relevance to an understanding of what medicine is or does. In making this case, I aim to show that the theoretical account of health offered by Christopher Boorse should be rejected because of its failings in this regard. (shrink)

Numerous approaches to a quantum theory of gravity posit fundamental ontologies that exclude spacetime, either partially or wholly. This situation raises deep questions about how such theories could relate to the empirical realm, since arguably only entities localized in spacetime can ever be observed. Are such entities even possible in a theory without fundamental spacetime? How might they be derived, formally speaking? Moreover, since the fundamental entities can't be smaller than the derived by assumption (since relative size is a spatiotemporal (...) notion) and so can't 'compose' them in any ordinary sense, would a formal derivation actually show the physical reality of localized entities? We address these questions via a survey of a range of theories of quantum gravity, and generally sketch how they may be answered positively. (shrink)

Increasingly, empirically minded moral philosophers are using data from cognitive science and neuroscience to resolve some longstanding philosophical questions about moral motivation, such as whether moral beliefs require the presence of a desire to motivate (Humeanism). These empirical approaches are implicitly committed to the existence of folk psychological (FP) mental states like beliefs and desires. However, data from the neuroscience of decision-making, particularly cellular-level work in neuroeconomics, is now converging with data from cognitive and social neuroscience to explain the processes (...) through which agents are moved to act on the basis of decisions, including decisions about social and moral norms. I argue that these developments are beginning to cast doubt on the prospect of finding nontrivial physical 'realizers' for the FP states invoked in the Humeanism dispute by posing two distinctive challenges that tend to work against each other: belief-desire directionality and causal relevance. (shrink)

In this paper I provide an account of physical symmetries, which are defined relative to a specific physical theory, and overarching symmetries, which hold across many different physical theories. I outline two general strategies for uniting disparate physical symmetries under the same overarching symmetry, calling the first "realist" and the second "conventionalist". Finally, I argue that, should physicists and philosophers be interested in finding symmetries that do interesting and helpful physical and metaphysical work, the realist strategy would serve them better (...) than the conventionalist strategy. (shrink)

It is striking that the concept of fitness although fundamental in evolutionary theory, still remains ambiguous. I argue here that time, although usually neglected, is an important parameter in regards to the concept of fitness. I will show some of the benefits of taking it seriously using the example of recent debates over evolutionary transitions in individuality. I start from Okasha's assertion that once an evolutionary transition in individuality is completed an ontologically new level of selection emerges from lower levels (...) of organization. I argue that Okasha's claim to have identified two ontologically distinct levels of selection is an artifact created by an undeserved comparison between the fitness of the collective level and the fitness of its constituents. Once fitness is assessed over the same period of time at the two levels of organization it becomes clear that only one, unique process of selection is acting upon both levels. (shrink)

Here is a challenge to IBE's epistemic credentials. If a reason is an epistemic reason for a subject to believe a proposition, then that reason increases the likelihood of the proposition's truth. But IBE relies on considerations like simplicity which do not increase the likelihood that hypotheses are truth. So, the reasons given by inference to the best explanation are not epistemic reasons. I contend that this argument fails, but not because, e.g., simplicity is truth-conducive. Rather, I show that the (...) argument relies on a version of epistemic value monism, which even the argument's proponents should reject. (shrink)

We argue for a new conventionalism about many kinds of evolutionary groups, including clades, cohesive units, and populations. This rejects a consensus, which says that given any one of the many legitimate grouping concepts, only objective biological facts determine whether a collection is such a group. Surprisingly, being any one kind of evolutionary group typically depends on which of many incompatible values are taken by suppressed variables. This is a novel pluralism underlying most any one group concept, rather than a (...) familiar pluralism claiming many concepts are legitimate. Consequently, we must help biological facts determine grouphood, even when given a single grouping concept. (shrink)

This is a draft of the introduction to the collective volume "The birth of string theory" (CUP, 2012), including the book's index and preface. The book explores the history of the theory’s early stages of development, as told by its main protagonists. It journeys from the first version of the theory (the so-called Dual Resonance Model) in the late 1960s, as an attempt to describe the physics of strong interactions outside the framework of quantum field theory, to its reinterpretation around (...) the mid-1970s as a quantum theory of gravity unified with the other interactions, and its successive developments up to the superstring revolution in 1984. The introductive Chapter summarizes the main developments and contains a chronological synopsis with a list of key results and publications. (shrink)

Recently, a number of authors have suggested that we understand scientific models in the same way as fictional characters, like Sherlock Holmes. The biggest challenge for this approach concerns the ontology of fictional characters. I consider two responses to this challenge, given by Roman Frigg, Ronald Giere and Peter Godfrey-Smith, and argue that neither is successful. I then suggest an alternative approach. While parallels with fiction are useful, I argue that models of real systems are more aptly compared to works (...) that portray real people, like the Emperor Claudius. This approach will allow us to avoid problems with fictional characters. (shrink)

Delayed-choice experiments in quantum mechanics are often taken to undermine a realistic interpretation of the quantum state. More specifically, Healey has recently argued that the phenomenon of delayed-choice entanglement swapping is incompatible with the view that entanglement is a physical relation between quantum systems. This paper argues against these claims. It first reviews two paradigmatic delayed-choice experiments and analyzes their metaphysical implications. It then applies the results of this analysis to the case of entanglement swapping, showing that such experiments pose (...) no threat to realism about entanglement. (shrink)

Within philosophy of physics it is broadly accepted that presentism as an empirical hypothesis has been falsified by the development of special relativity. In this paper, I identify and reject an assumption common to both presentists and advocates of the block universe, and then offer an alternative version of presentism that does not begin from spatiotemporal structure, which is an empirical hypothesis, and which has yet to be falsified. I fear that labelling it “presentism” dooms the view, but I don’t (...) know what else to call it. (shrink)

In this paper I argue that reading history of physics as a contribution to history of philosophy is important for contemporary philosophy of physics. My argument centers around a particular case: special relativity versus presentism. By means of resources drawn from reading aspects of Newton's work as contributions to philosophy, I argue that there is in physics an alternative way to approach what we mean by "present" such that (without adding any preferred foliation or anything like that) presentism remains an (...) open empirical question whose refutation requires resources that go beyond those of special relativity. I offer this as an example of one fruitful way in which we pursue integrated HPS. (shrink)

Many scientific models are non-representational in that they refer to merely possible processes, background conditions and results. The paper shows how such non-representational models can be appraised, beyond the weak role that they might play as heuristic tools. Using conceptual distinctions from the discussion of how-possibly explanations, six types of models are distinguished by their modal qualities of their background conditions, model processes and model results. For each of these types, an actual model example – drawn from economics, biology, psychology (...) or sociology – is discussed. For each case, contexts and purposes are identified in which the use of such a model offers a genuine opportunity to learn – i.e. justifies changing one’s confidence in a hypothesis about the world. These cases then offer novel justifications for modelling practices that fall between the cracks of standard representational accounts of models. (shrink)

The following describes one distinct sense of ‘mechanism’ which is prevalent in biology and biomedicine and which has important epistemic benefits. According to this sense, mechanisms are defined by the functions they facilitate. This construal has two important implications. Firstly, mechanisms that facilitate functions are capable of breaking. Secondly, on this construal, there are rigid constraints on the sorts of phenomena ‘for which’ there can be a mechanism. In this sense, there are no ‘mechanisms for’ pathology, and natural selection is (...) not a ‘mechanism of’ evolution, because it does not serve a function. (shrink)

I examine Carrier’s and Ladyman’s structural realist (‘SR’) explanation of the predictive success of phlogiston chemistry. On their account, it succeeds because phlogiston chemists grasped that there is some common unobservable structure of relations underlying combustion, calcification, and respiration. I argue that this SR account depends on assuming the truth of current chemical theory of oxidation and reduction, which provides a better explanation of the success of phlogiston theory than SR provides. I defend an alternative version of inference-to-the-best-explanation scientific realism (...) which I call ‘Best Current Theory Realism’ (BCTR) and argue that it can answer the pessimistic meta-induction. (shrink)

Randomized Controlled Trials (RCTs) are currently the gold standard within evidence-based medicine. Usually, they are conducted as sequential trials allowing for monitoring for early signs of effectiveness or harm. However, evidence from early stopped trials is often charged with being biased towards implausibly large effects (e.g., Bassler et al. 2010). To our mind, this skeptical attitude is unfounded and caused by the failure to perform appropriate conditioning in the statistical analysis of the evidence. We contend that a shift from unconditional (...) hypothesis tests in the style of Neyman and Pearson to conditional hypothesis tests (Berger, Brown and Wolpert 1994) gives a superior appreciation of the obtained evidence and significantly improves the practice of sequential medical trials, while staying firmly rooted in frequentist methodology. (shrink)

The interpretation of tests of a point null hypothesis against an unspecified alternative is a classical and yet unresolved issue in statistical methodology. This paper approaches the problem from the perspective of Lindley's Paradox: the divergence of Bayesian and frequentist inference in hypothesis tests with large sample size. I contend that the standard approaches in both frameworks fail to resolve the paradox. As an alternative, I suggest the Bayesian Reference Criterion: (i) it targets the predictive performance of the null hypothesis (...) in future experiments; (ii) it provides a proper decision-theoretic model for testing a point null hypothesis and (iii) it convincingly accounts for Lindley's Paradox. (shrink)

Participatory research in anthropology attempts to turn informants into collaborators, even colleagues. Researchers generally accept the idea of different knowledge systems, and the practice of avoiding critical appraisal of alien knowledge systems, common in ethnography, is continued within participatory research. However, if the aim of participatory research is to turn informants into collaborators, or ideally colleagues, the ethical imperative of offering constructive criticism to colleagues should apply to them, too, even if they are seen as representing different knowledge systems than (...) the researchers. Avoiding appraisal of alien knowledge systems is problematic when the knowledge systems of the researcher and the researched are in constant contact. (shrink)

In this paper, we show how the discovery of the circulation of the blood by William Harvey (1578-1657) sheds new light on traditional models of creativity in science. In particular, the example illustrates where both the enlightenment and the romantic view on creativity go astray. In the first section, we sketch the two views and present a (non-exhaustive) list of problems for both. In the remainder of the paper, we demonstrate how William Harvey’s discovery, as a historical case study of (...) creativity in science, gives firmer ground to these objections. (shrink)

While introspective methods went out of favour with the decline of Titchener’s analytic school, many important questions concern the rehabilitation of introspection in contemporary psychology. Hatfield (2005) rightly points out that introspective methods should not be confused with analytic ones, and goes on to describe their “ineliminable role” in perceptual psychology. Here I argue that certain methodological conventions within psychophysics reflect a continued uncertainty over appropriate use of subjects’ perceptual observations and the reliability of their introspective judgements. My first claim (...) is that different psychophysical methods do not rely equally on the introspective capabilities of experimental subjects. I contrast “minimally-introspective” tasks with “introspection-heavy” ones. It is only in the latter, I argue, that introspection can be said to have a non-trivial role in the subjects’ performance. My second claim is that my rough-and-ready distinction maps onto a number of important “dichotomies” in vision science (Kingdom and Prins 2009). Not coincidentally, the introspection-heavy categorisation captures many of the tasks typically considered less able to yield useful information regarding the processes underlying visual sensation. (shrink)

We develop a point-free construction of the classical one- dimensional continuum, with an interval structure based on mereology and either a weak set theory or logic of plural quantification. In some respects this realizes ideas going back to Aristotle,although, unlike Aristotle, we make free use of classical "actual infinity". Also, in contrast to intuitionistic, Bishop, and smooth infinitesimal analysis, we follow classical analysis in allowing partitioning of our "gunky line" into mutually exclusive and exhaustive disjoint parts, thereby demonstrating the independence (...) of "indecomposability" from a non-punctiform conception. It is surprising that such simple axioms as ours already imply the Archimedean property and that they determine an isomorphism with the Dedekind-Cantor structure of R as a complete, separable, ordered field. We also present some simple topological models of our system, establishing consistency relative to classical analysis. Finally, after describing how to nominalize our theory, we close with comparisons with earlier efforts related to our own. (shrink)

This paper provides a new context for an established metaphysical debate regarding the problem of persistence. I contend that perdurance (the claim that objects persist by having temporal parts) can be precisely formulated in quantum mechanics due to an analogy with spatial parts, which I claim correspond to the decomposition of the quantum state provided by a localization scheme. However, I present a `no-go' result that rules out the existence of an analogous temporal localization scheme, and so argue that quantum (...) objects cannot be said to perdure. I conclude by surveying the remaining metaphysical options. (shrink)

In this paper I examine a well-known articulation of the skeptical view of human nature, a paper by Hull (1986). I then review a recent reply to Hull by Machery (2008). I show that Machery’s account of human nature is not very useful and is scientifically suspect. Finally, I introduce an alternative account of human nature—the “life-history trait cluster” conception of human nature—which I hold is scientifically sound, pragmatically useful, and makes sense of (at least some of) our intuitions about (...) human (or, more generally, species) nature. (shrink)

My aim is to show how a strategy used in the experimental sciences, which I name “interinstrumentality”, can minimize the role of sociological factors when one tries to understand how the debates about the interpretation of data come to an end. To defend this view, two examples are presented. The first is historical – the invention of the Scanning Tunneling Microscope (STM) – and the second is collected during an ethnographic study in a surface science laboratory. I would like to (...) emphasize that interinstrumentality contributes to objectivity of the experimental results and constitutes a part of it as well as intersubjectivity. (shrink)

The notion of (computational) template has recently been discussed in relation to cross-disciplinary transfer of modeling efforts and in relation to the representational content of models. We further develop and disambiguate the notion of template and find that, suitably developed, it is useful in distinguishing and analyzing different types of transfer, none of which supports a non-representationalist view of models. We illustrate our main findings with the modeling of technology substitution with Lotka-Volterra Competition equations.

In this work we present a logical reconstruction of Leonard Bloom- field’s theory of structural linguistics. First, the central notions of this theory are analyzed and discussed. In the following section, a recon- struction with the so-called structuralist approach in the philosophy of science is presented. After defining the general framework of Bloom- field’s theory, questions of lawlikeness and theoretical terms will be discussed. In a further step, this work aims to contribute to the dis- cussion of theory change and (...) scientific realism, applied to linguistic theory. After the reconstruction of further theories of linguistics, it can be studied whether certain inter theoretical relations hold. It aims to be a contribution to the discussion on the foundations of linguistics. (shrink)

Starting, at first, from some little known but notable formal remarks made by the mathematician Gabriele Darbo about the qualitative dimensional analysis of the physical quantities, for then, above all, take into account some latest science education (d’après diSessa) and philosophy (d’après Gärdenfors) research results, it shall be possible, paraphrasing a celebrated 1851 work of Arthur Schopenhauer, work out a kind of Parerga und Paralipòmena of the basic J-M. Lévy-Leblond paper On the Conceptual Nature of the Physical Constants, published in (...) Rivista del Nuovo Cimento in 1977. The epistemological reconnaissance thereof, might turn out to be of some usefulness in the physics education context as regard, for instance, the meaning of the physical constants, their values and possible further epistemological and pedagogical implications. (shrink)

Mainly on the basis of some notable physical examples reported in a 1929 Oscar Chisini paper, in this brief note it is exposed further possible historic-critical remarks on the definition of statistical mean which lead us towards the realm of Integral Geometry, via the Felix Klein Erlanger Programm.

Advocates of the counterfactual approach to causal inference argue that race isn’t a cause. I object that their argument is invalid and that its key premise is unwarranted. I also criticize the criterion, which I call ‘Holland’s rule’, the counterfactual approach relies on to distinguish causes from non-causes. Finally, I argue that racial discrimination cannot be causally explained unless one assumes race to be a cause. I conclude that the view that race is not a cause lacks support and that (...) there are good reasons to adopt the opposite view that race is a cause. (shrink)

In axiomatic approaches to expert opinion aggregation, so-called independence conditions have been ubiquitous. Such conditions dictate that the group value assigned to each decision variable should depend only on the values assigned by individuals to that variable, taking no account of values that they assign to other variables. This radically anti-holistic stricture on the synthesis of expert opinion severely limits the set of allowable aggregation methods. As we show, the limitations are particularly acute in the case of three or more (...) variables which must be assigned nonnegative real values summing to a fixed positive real number s. For if the subset V of [0,s] comprising the allowable values of the variables satisfies the closure conditions (i)0 is an element of V ; (ii) if x is an element of V, then s-x is an element of V ; and (iii) if x and y are elements of V and x+y is an element of [0,s], then x+y is an element of V, then, if V is finite, which is always the case in practice, subjecting the aggregation of such s-allocations to an independence condition allows only for dictatorial or imposed (i.e., constant) aggregation. (shrink)

The manipulationist account of causation provides a conceptual analysis of cause-effect relationships in terms of hypothetical experiments. It also explains why and how experiments are used for the empirical testing of causal claims. This paper attempts to apply the manipulationist account of causation to a broader range of experiments—a range that extends beyond experiments explicitly designed for the testing of causal claims. I aim to show (1) that the set of causal inferences afforded by an experiment is determined solely on (...) the basis of contrasting case structures that I call “experimental series”, and (2) that the conditions that suffice for causal inference obtain quite commonly, even among “ordinary” experiments that are not explicitly designed for the testing of causal claims. (shrink)

This paper aims to critically discuss the versatility of Popper’s theory of three worlds in the analysis of issues related to the ontological status and character of technical artifacts. Despite being discussed over years and hit with numerous criticisms it is still little known that Popper’s thesis has an important bearing on the philosophical characterization of technical artifacts. His key perspectives on the reality, autonomy, and ontological status of artifacts are rarely taken into consideration by scholars known to be engaged (...) in the study of artifacts. This paper consists of two main sections. The first section attempts to present a critical exposition of Popper’s account of reality and (partial) autonomy of artifacts. Recent discussions about the longstanding distinction between natural objects and artifacts are brought up and the relevance of Popper’s pluralistic thesis to this debate is pointed out. In addition, attention is drawn towards how to read his notion of the autonomy of artifacts. The primary emphasis of the second section is the ontological position of artifacts. Two separate arguments are posed to challenge the dual ontological status of what Popper called ‘embodied’ World 3 objects or artifacts. The first argument is concerned with the material composition and characteristic features of artifacts. The second one addresses the creative and epistemic value of these artificial products. (shrink)

Einsteins relativity of simultaneity had a deep impact on the pilosophy of time. A first conclusion is that there is no such thing as absolute time. Furthermore according to relativity of simultaneity there is no present in which an open future could come into existence and then pass into a fixed past. According to relativity of simultaneity there is no becoming in a three-dimensional space. There are just changes in a four-dimensional world, often called "block universe". Although many authors refuse (...) this static interpretation of space-time, there is little doubt in the relativity of simultaneity. This is astonishing, because in the present cosmological models the relativity of simultaneity is not valid and the work of Hawking and Ellis has shown that there is good reason to refuse this principle. (shrink)

Many discussions of emergence focus on the putatively irreducible causal powers of emergents. I argue that the question of whether emergents are irreducible causes should be postponed in favor of the question of whether emergents are natural. David Lewis contends that scientifically interesting properties are natural: they account for resemblances and distinguish causally relevant and irrelevant properties. I consider bimanual coordination, as described by the HKB model, as an example of natural emergence. I conclude that emergent properties are those that (...) systemic processes have when they exhibit “instability” and argue that instability is the natural property that unites these processes. (shrink)

These preprints were automatically compiled into a PDF from the collection of papers deposited in PhilSci-Archive in conjunction with the PSA 2012.

The present paper attempts to show that a 1915 article by Erich Kretschmann must be credited not only for being the source of Einstein’s point-coincidence remark, but also for having anticipated the main lines of the logical-empiricist interpretation of general relativity. Whereas Kretschmann was inspired by the work of Mach and Poincaré, Einstein inserted Kretschmann’s point-coincidence parlance into the context of Ricci and Levi-Civita’s absolute differential calculus. Kretschmann himself realized this and turned the point-coincidence argument against Einstein in his second (...) and more famous 1918 paper. While Einstein had taken nothing from Kretschmann but the expression “point-coincidences”, the logical empiricists, however, instinctively dragged along with it the entire apparatus of Kretschmann’s conventionalism. Disappointingly, in their interpretation of general relativity, the logical empiricists unwittingly replicated some epistemological remarks Kretschmann had written before General Relativity even existed. (shrink)

In the early 1920s, Hans Reichenbach and Kurt Lewin presented two topological accounts of time that appear to be interrelated in more than one respect. Despite their different approaches, their underlying idea is that time order is derived from specific structural properties of the world. In both works, moreover, the notion of genidentity--i.e., identity through or over time--plays a crucial role. Although it is well known that Reichenbach borrowed this notion from Kurt Lewin, not much has been written about their (...) relationship, nor about the way Lewin implemented this notion in his own work in order to ground his topology. This paper examines these two early versions of the topology of time, and follows the extent of Lewin’s influence on Reichenbach’s proposal. (shrink)

In 1994, Maudlin proposed an objection to retrocausal approaches to quantum mechanics in general, and to the transactional interpretation (TI) in particular, involving an absorber that changes location depending on the trajectory of the particle. Maudlin considered this objection fatal. However, the TI did not die; rather, a number of responses were developed, some attempting to accommodate Maudlin'�s example within the existing TI, and others modifying the TI. I argue that none of these responses is fully adequate. The reason, I (...) submit, is that there are two aspects to Maudlin�s objection; the more readily soluble aspect has received all the attention, but the more problematic aspect has gone unnoticed. I consider the prospects for developing a succesful retrocausal quantum theory in light of this second aspect of the objection. (shrink)

The Simulation Argument and the Doomsday Argument share certain structural similarities, and hence are often discussed together (Bostrom 2003, Aranyosi 2004, Richmond 2008, Bostrom and Kulczycki 2011). Both are cases where reflecting on one’s location among a set of possibilities yields a counter-intuitive conclusion—in one case that the end of humankind is closer than you initially thought, and in the second case that it is more likely than you initially thought that you are living in a computer simulation. Indeed, the (...) two arguments do share strong structural similarities. But there are also some disanalogies between the two arguments, and I argue that these disanalogies mean that the Simulation Argument succeeds and the Doomsday Argument fails. (shrink)

There is an important sense in which an agent’s credences are universal: while they reflect an agent’s own judgments, those judgments apply equally to everyone’s bets. This point, while uncontentious, has been overlooked; people automatically assume that credences concern an agent’s own bets, perhaps just because of the name “subjective” that is typically applied to this account of belief. This oversight has had unfortunate consequences for recent epistemology, in particular concerning the Sleeping Beauty case and its myriad variants.

In 1994, Maudlin proposed proposed an objection to the transactional interpretation (TI), involving an absorber that changes location depending on the trajectory of the particle. Maudlin considered this objection fatal. However, the TI did not die; rather, a number of responses were developed, some attempting to accommodate Maudlin's example within the existing TI, and others modifying the TI. I argue that none of these responses is fully adequate. The reason, I submit, is that there are two aspects to Maudlin's objection; (...) the more readily soluble aspect has received all the attention, but the more problematic aspect has gone unnoticed. I consider the prospects for developing a succesful version of the TI in light of this second aspect of the objection. (shrink)

The point of this note is to compare the Doomsday Argument to the Simulation Argument. The latter, I maintain, is a better argument than the former.

In this note, I briefly review Lyre’s (2008) analysis and interpretation of the Higgs mechanism. Contrary to Lyre, I maintain that, on the proper understanding of the term, the Higgs mechanism refers to a physical process in the course of which gauge bosons acquire a mass. Since also Lyre’s worries about imaginary masses can be dismissed, a realistic interpretation of the Higgs mechanism seems viable. While it may remain an open empirical question whether the Higgs mechanism did actually occur in (...) the early history of the universe and what the details of the mechanism are, I claim that the term can certainly refer to a physical process. (shrink)

The thesis of theory-ladenness of observations, in its various guises, is widely considered as either ill-conceived or harmless to the rationality of science. The latter view rests partly on the work of the proponents of New Experimentalism who have argued, among other things, that experimental practices are efficient in guarding against any epistemological threat posed by theory-ladenness. In this paper I show that one can generate a thesis of theory-ladenness for experimental practices from an influential New Experimentalist account. The notion (...) I introduce for this purpose is the concept of ‘theory-driven data reliability judgments’ (TDR), according to which theories which are sought to be tested with a particular set of data guide reliability judgments about those very same data. I provide various prominent historical examples (among others, the confirmation of Einstein’s prediction of star light bending in 1919) to show that TDRs are used by scientists to resolve data conflicts. I argue that the rationality of the practices which employ TDRs can be saved if the independent support of the theories driving TDRs is construed in a particular way. (shrink)

The paper points out that the modern formulation of Bohm’s quantum theory known as Bohmian mechanics is committed only to particles’ positions and a law of motion. We explain how this view can avoid the open questions that the traditional view faces according to which Bohm’s theory is committed to a wave-function that is a physical entity over and above the particles, although it is defined on configuration space instead of three-dimensional space. We then enquire into the status of the (...) law of motion, elaborating on how the main philosophical options to ground a law of motion, namely Humeanism and dispositionalism, can be applied to Bohmian mechanics. In conclusion, we sketch out how these options apply to primitive ontology approaches to quantum mechanics in general. (shrink)

One hotly debated philosophical question in the analysis of evolutionary theory concerns whether or not evolution and the various factors which constitute it (selection, drift, mutation, and so on) may profitably be considered to be “forces” in the traditional, Newtonian sense. Several compelling arguments assert that the force picture is incoherent, due to the peculiar nature of genetic drift. I consider two of those arguments here – that drift lacks a predictable direction, and that drift is constitutive of evolutionary systems (...) – and show that they both fail to demonstrate that a view of genetic drift as a force is untenable. (shrink)

Diagrams have distinctive characteristics that make them an effective medium for communicating research findings, but they are even more impressive as tools for scientific reasoning. Focusing on circadian rhythm research in biology to explore these roles, we examine diagrammatic formats that have been devised (a) to identify and illuminate circadian phenomena and (b) to develop and modify mechanistic explanations of these phenomena.

The permutation symmetry of quantum mechanics is widely thought to imply a sort of metaphysical underdetermination about the identity of particles. Despite claims to the contrary, this implication does not hold in the more fundamental quantum field theory, where an ontology of particles is not generally available. Although permutations are often defined as acting on particles, a more general account of permutation symmetry can be formulated using superselection theory. As a result, permutation symmetry applies even in field theories with no (...) particle interpretation. The quantum mechanical account of permutations acting on particles is recovered as a special case. (shrink)

As it is well known, classical special relativity allows the existence of three different kinds of particles: bradyons, luxons and tachyons. Bradyons have non-zero mass and hence always travel slower than light. Luxons are particles with zero mass, like the photon, and they always travel with invariant velocity. Tachyons are hypothetical superluminal particles that always move faster than light. The existence of bradyons and luxons is firmly established, while the tachyons were never reliably observed. In quantum field theory, the appearance (...) of tachyonic degrees of freedom indicates vacuum instability rather than a real existence of the faster-than-light particles. However, recent controversial claims of the OPERA experiment about superluminal neutrinos triggered a renewed interest in superluminal particles. Driven by a striking analogy of the old Frenkel-Kontorova model of a dislocation dynamics to the theory of relativity, we conjecture in this note a remarkable possibility of existence of the forth type of particles, elvisebrions, which can be superluminal. The characteristic feature of elvisebrions, distinguishing them from tachyons, is that they are outside the realm of special relativity and their energy remains finite (or may even turn to zero) when the elvisebrion velocity approaches the light velocity. (shrink)

This is Part I of a two-part essay introducing case-intensional first-order logic (CIFOL), an easy-to-use, uniform, powerful, and useful combination of first order logic with modal logic resulting from philosophical and technical modifications of Bressan’s General interpreted modal calculus (Yale University Press 1972). CIFOL starts with a set of cases; each expression has an extension in each case and an intension, which is the function from the cases to the respective case-relative extensions. Predication is intensional; identity is extensional. Definite descriptions (...) are context-independent terms, and lambda-predicates and -operators can be introduced without constraints. These logical resources allow one to define, within CIFOL, important properties of properties, viz., extensionality (whether the property applies, depends only on an extension in one case) and absoluteness, Bressan’s chief innovation that allows tracing an individual across cases without recourse to any notion of “rigid designation” or “trans-world identity.” Thereby CIFOL abstains from incorporating any metaphysical principles into the quantificational machinery, unlike extant frameworks of quantified modal logic. We claim that this neutrality makes CIFOL a useful tool for discussing both metaphysical and scientific arguments involving modality and quantification, and we illustrate by discussing in diagrammatic detail a number of such arguments involving the extensional identification of individuals via absolute (substance) properties, essential properties, de re vs. de dicto, and the results of possible tests. (shrink)

Some aspects of Federigo Enriques mathematical philosophy thought are taken as central reference points for a critical historic-epistemological comparison between it and some of the main aspects of the thought of other his contemporary thinkers like Gaston Bachelard and Hermann Weyl. From what will be exposed, it will be also possible descry eventual educational implications of the historic-epistemological approach.

How are beliefs efficacious? One answer is: via rational intentional action. But there are other ways that beliefs are efficacious. This dissertation examines these other ways, and sketches an answer to the question of how beliefs are efficacious that takes into account how beliefs are involved in the full range of behavioral disciplines, from psychophysiology and cognition to social and economic phenomena. The account of how beliefs are efficacious I propose draws on work on active accounts of perception. I develop (...) an account based on a proposal sketched by the cognitive scientist Ulrich Neisser. Neisser sketched an active account of perception, on which dynamic anticipatory schemata direct an organism's exploration and action, and are in turn revised as a result of exploration and action. This notion of schema has roots in nineteenth century neurophysiology and in Frederick Bartlett's subsequent work on memory. Neisser appealed to it to unite what he thought was right about information-processing accounts of perception with what he thought was right about ecological accounts of perception. The point that we must anticipate in order to perceive has been recognized by philosophers in the form of the "theory-ladenness of observation." I extend the concept of anticipatory schema to include its role in social perception and social interaction; the concept of anticipatory schema provides a more interactive account of the role of expectations in the maintenance and existence of social institutions, and can be used to enrich the account of convention David Lewis provided. I also show that the concept of rational expectations, which explains the neutrality of money in terms of the efficacy of anticipatory expectations, is compatible with the proposed account of how beliefs are efficacious. I discuss how the proposal accounts for the three main modes by which beliefs can be efficacious: (i) via their role in causing intentional action, (ii) via their role in causing economic phenomena and the existence and maintenance of social institutions, and (iii) via their role in causing unintentional physiological responses, including anticipatory physiological responses that can enable perception, cause involuntary actions and give rise to the placebo effect. (shrink)

This paper explores the question of the unifi�cation of the three basic languages of physics, the geometric language of forces, the geometric language of fi�elds or 4-dimensional space-time, and the probabilistic language of quantum mechanics. I will show that on the one hand, equations in each of these languages may be derived from any form of the Principle of Least Action (PLA). On the other hand, Feynman's `path integral' method could explain the physical sense of these particular forms of PLA. (...) In conclusion, I will show that the axioms of classical and relativistic mechanics become consequences of Feynman's formulation of quantum mechanics. (shrink)

How are beliefs efficacious? One answer is: via rational intentional action. But there are other ways that beliefs are efficacious. This dissertation examines these other ways, and sketches an answer to the question of how beliefs are efficacious that takes into account how beliefs are involved in the full range of behavioral disciplines, from psychophysiology and cognition to social and economic phenomena. The account of how beliefs are efficacious I propose draws on work on active accounts of perception. I develop (...) an account based on a proposal sketched by the cognitive scientist Ulrich Neisser. Neisser sketched an active account of perception, on which dynamic anticipatory schemata direct an organism's exploration and action, and are in turn revised as a result of exploration and action. This notion of schema has roots in nineteenth century neurophysiology and in Frederick Bartlett's subsequent work on memory. Neisser appealed to it to unite what he thought was right about information-processing accounts of perception with what he thought was right about ecological accounts of perception. The point that we must anticipate in order to perceive has been recognized by philosophers in the form of the "theory-ladenness of observation." I extend the concept of anticipatory schema to include its role in social perception and social interaction; the concept of anticipatory schema provides a more interactive account of the role of expectations in the maintenance and existence of social institutions, and can be used to enrich the account of convention David Lewis provided. I also show that the concept of rational expectations, which explains the neutrality of money in terms of the efficacy of anticipatory expectations, is compatible with the proposed account of how beliefs are efficacious. I discuss how the proposal accounts for the three main modes by which beliefs can be efficacious: (i) via their role in causing intentional action, (ii) via their role in causing economic phenomena and the existence and maintenance of social institutions, and (iii) via their role in causing unintentional physiological responses, including anticipatory physiological responses that can enable perception, cause involuntary actions and give rise to the placebo effect. (shrink)

Evolution is often characterized as a tinkerer that creates efficient but messy solutions to problems. We analyze the nature of the problems that arise when we try to explain and understand cognitive phenomena created by this haphazard design process. We present a theory of explanation and understanding and apply it to a case problem – solutions generated by genetic algorithms. By analyzing the nature of solutions that genetic algorithms present to computational problems, we show that the reason for why evolutionary (...) designs are often hard to understand is that they exhibit non-modular functionality, and that breaches of modularity wreak havoc on our strategies of causal and constitutive explanation. (shrink)

I argue that the standard interpretation of Leibniz as a relationist about space is mistaken, and defend a reading according to which his correspondence with Samuel Clarke actually suggests that Leibniz holds a view closely resembling modern spacetime structuralism. I distinguish my proposal from Belot's recent reading of Leibniz as a modal relationist, arguing for the superiority of my reading based on the Clarke correspondence and on Leibniz's conception of God's relation to the created world. I note a tension between (...) my proposal and Leibniz's ontology, and suggest that a solution is forthcoming and worth pursuing. (shrink)

Theories of scientific representation, following Chakrawartty's categorization, are divided into two groups. Whereas cognitive-functional views emphasize agents' intentions, informational theories stress the objective relation between represented and representing. In the first part, a modified structuralist theory is introduced that takes into account agents' intentions. The second part is devoted to dismissing a criticism against the structural account of representation on which similarity as the backbone of representation raises serious problems, since it has definite logical features, i.e. reflexivity, symmetry and transitivity, (...) which representation lacks. Drawing on the representational relation between quantum and statistical field theories, I argue that scientific representation displays these logical features, although depending on the context they may be used or not. (shrink)

A draft version of Chapter 11 of the edited volume 'Interpreting Bodies. Classical and Quantum Objects in Modern Physics', (Princeton UP, 1998). The Chapter is devoted to illustrating the group-theoretic approach to the issue of physical objects. In particular, the Chapter discusses the group-theoretic constitution of classical and quantum particles in the nonrelativistic case.

We propose a technical reformulation of the measurement problem of quantum mechanics, which is based on the postulate that the final state of a measurement is classical; this accords with experimental practice as well as with Bohr's views. Unlike the usual formulation (in which the post-measurement state is a a unit vector in Hilbert space, such as a wave-function), our version actually admits a purely technical solution within the confines of conventional quantum theory (as opposed to solutions that either modify (...) this theory, or introduce unusual and controversial interpretative rules and/or ontologies). To that effect, we recall a remarkable phenomenon in the theory of Schroedinger operators (discovered in 1981 by Jona-Lasinio, Martinelli, and Scoppola), according to which the ground state of a symmetric double-well Hamiltonian (which is paradigmatically of Schroedinger's Cat type) becomes exponentially sensitive to tiny perturbations of the potential as h -> 0. We show that this instability emerges also from the textbook WKB approximation, extend it to time-dependent perturbations, and study the dynamical transition from the ground state of the double well to the perturbed ground state (in which the cat is typically either dead or alive, depending on the details of the perturbation). Numerical simulations show that, in an individual experiment, certain (especially adiabatically rising) perturbations may (quite literally) cause the collapse of the wavefunction in the classical limit. Thus we combine the technical and conceptual virtues of dynamical collapse models a la GRW (which do solve the measurement problem) with those of decoherence (in that our perturbations come from the environment) without sharing their drawbacks: although single measurement outcomes are obtained (instead of merely diagonal reduced density matrices), no modification of quantum mechanics is needed. (shrink)

Most scientists would hold that science has not established that the cosmos is physically comprehensible – i.e. such that there is some as-yet undiscovered true physical theory of everything that is unified. This is an empirically untestable, or metaphysical thesis. It thus lies beyond the scope of science. Only when physics has formulated a testable unified theory of everything which has been amply corroborated empirically will science be in a position to declare that it has established that the cosmos is (...) physically comprehensible. But this argument presupposes a widely accepted but untenable conception of science which I shall call standard empiricism. According to standard empiricism, in science theories are accepted solely on the basis of evidence. Choice of theory may be influenced for a time by considerations of simplicity, unity, or explanatory capacity, but not in such a way that the universe itself is permanently assumed to be simple, unified or physically comprehensible. In science, no thesis about the universe can be accepted permanently as a part of scientific knowledge independently of evidence. Granted this view, it is clear that science cannot have established that the universe is physically comprehensible. Standard empiricism is, however, as I have indicated, untenable. Any fundamental physical theory, in order to be accepted as a part of theoretical scientific knowledge, must satisfy two criteria. It must be (1) sufficiently empirically successful, and (2) sufficiently unified. Given any accepted theory of physics, endlessly many empirically more successful disunified rivals can always be concocted – disunified because they assert that different dynamical laws govern the diverse phenomena to which the theory applies. These disunified rivals are not considered for a moment in physics, despite their greater empirical success. This persistent rejection of empirically more successful but disunified rival theories means, I argue, that a big, highly problematic, implicit assumption is made by science about the cosmos, to the effect, at least, that the cosmos is such that all seriously disunified theories are false. Once this point is recognized, it becomes clear, I argue, that we need a new conception of science which makes explicit, and so criticizable and improvable the big, influential, and problematic assumption that is at present implicit in physics in the persistent preference for unified theories. This conception of science, which I call aim-oriented empiricism, represents the assumption of physics in the form of a hierarchy of assumptions. As one goes up the hierarchy, the assumptions become less and less substantial, and more and more nearly such that their truth is required for science, or the pursuit of knowledge, to be possible at all. At each level, that assumption is accepted which (a) best accords with the next one up, and (b) has, associated with it the most empirically progressive research programme in physics, or holds out the greatest hope of leading to such an empirically progressive research programme. In this way a framework of relatively insubstantial, unproblematic, fixed assumptions and associated methods is created, high up in the hierarchy, within which much more substantial and problematic assumptions and associated methods, low down in the hierarchy, can be changed, and indeed improved, as scientific knowledge improves. One assumption in this hierarchy of assumptions, I argue, is that the cosmos is physically comprehensible – that is, such that some yet-to-be-discovered unified theory of everything is true. Hence the conclusion: improve our ideas about the nature of science and it becomes apparent that science has already established that the cosmos is physically comprehensible – in so far as science can ever establish anything theoretical. (shrink)

Several modern accounts of explanation acknowledge the importance of abstraction and idealization for our explanatory practice. However, once we allow a role for abstraction, questions remain. I ask whether the relation between explanations at different theoretical levels should be thought of wholly in terms of abstraction, and argue that changes of variable between theories can lead to novel explanations that are not merely abstractions of some more detailed picture. I use the example of phase transitions as described by statistical mechanics (...) and thermodynamics to illustrate this, and to demonstrate some details of the relationship between abstraction, idealization, and novel explanation. (shrink)

I argue that the fundamental space of a quantum mechanical world is the wavefunction's space. I argue for this using some very general principles that guide our inferences to the fundamental nature of a world, for any fundamental physical theory. I suggest that ordinary three-dimensional space exists in such a world, but is non-fundamental; it emerges from the fundamental space of the wavefunction.

Of the many and varied applications of quantum information theory, perhaps the most fascinating is the sub-field of quantum computation. In this sub-field, computational algorithms are designed which utilise the resources available in quantum systems in order to compute solutions to computational problems with, in some cases, exponentially fewer resources than any known classical algorithm. While the fact of quantum computational speedup is almost beyond doubt, the source of quantum speedup is still a matter of debate. In this paper I (...) argue that entanglement is a necessary component for any explanation of quantum speedup and I address some purported counter-examples that some claim show that the contrary is true. In particular, I address Biham et al.'s mixed-state version of the Deutsch-Jozsa algorithm, and Knill \& Laflamme's deterministic quantum computation with one qubit (DQC1) model of quantum computation. I argue that these examples do not demonstrate that entanglement is unnecessary for the explanation of quantum speedup, but that they rather illuminate and clarify the role that entanglement does play. (shrink)

You and I are highly unlikely to exist in a civilization that has produced only 70 billion people, yet we find ourselves in just such a civilization. Our circumstance, which seems difficult to explain, is easily accounted for if (1) many other civilizations exist and if (2) nearly all of these civilizations (including our own) die out sooner than usually thought, i.e., before trillions of people are produced. Because the combination of (1) and (2) make our situation likely and alternatives (...) do not, we should drastically increase our belief that (1) and (2) are true. These results follow immediately when considering a many worlds version of the ``Doomsday Argument'' and are immune to the main criticism of the original Doomsday Argument. (shrink)

General criticism of Frank Arntzenius's paper ``Some problems for conditionalization and reflection''.

In this essay, I review the relationship between Charles Darwin's methodology and the philosophy of science of Sir John F. W. Herschel. Darwin's exposure to Herschel's philosophy was, I argue, significant. Further, when we construct an appropriate reading of Herschel's philosophy of science (a surprisingly difficult feat), we can see that Darwin's three-part argument in the Origin is crafted in order to strictly adhere to Herschel's methodological guidelines.

Using the Hilbert–Bernays account as a spring-board, we first define four ways in which two objects can be discerned from one another, using the non-logical vocabulary of the language concerned. (These definitions are based on definitions made by Quine and Saunders.) Because of our use of the Hilbert-Bernays account, these definitions are in terms of the syntax of the language. But we also relate our definitions to the idea of permutations on the domain of quantification, and their being symmetries. These (...) relations turn out to be subtle—some natural conjectures about them are false. We will see in particular that the idea of symmetry meshes with a species of indiscernibility that we will call ‘absolute indiscernibility’. We use these four kinds as a resource for stating four metaphysical theses about identity. Three of these theses articulate two traditional philosophical themes: viz. the principle of the identity of indiscernibles (which will come in two versions), and haecceitism. The fourth is recent. Its most notable feature is that it makes diversity (i.e. non-identity) weaker than what we will call individuality (being an individual): two objects can be distinct but not individuals. For this reason, it has been advocated both for quantum particles and for spacetime points. Finally, we locate this fourth metaphysical thesis in a broader position, which we call structuralism. We conclude with a discussion of the semantics suitable for a structuralist, with particular reference to physical theories as well as elementary model theory. (shrink)

We present a counterexample to Krasnikov's (2002) much discussed time machine no-go result. In addition, we prove a positive statement: a time machine existence theorem under a modest "no holes" assumption.

In this paper we try to justify our way of looking for an alternative approach to quantum mechanics, which is based on a non-classical logic. We consider two specific questions related to quantum theory, namely, entanglement and the indiscernibility of quanta. We characterize individuals, and then explain in what sense entanglement is a concept which can be applied to individuals in a restricted sense only. Then, we turn to indiscernibility and, after realizing that this concept is of a fundamental importance, (...) we mention the ‘traditional’ theory of identity (TTI) of standard logic and mathematics, which underly the basic formalism of quantum theory. Then we propose to call the Problem of Identity the question whether identity of objects can be justified, and under what conditions. As in the Hume’s celebrated Problem of Induction, we conclude that the attribution of transtemporal identity to an object (either a macroscopic or a microscopic one) has no logic justification, and must be considered as a metaphysical hypothesis. Numerical identity is also put aside for similar reasons. Then we guess that identity is just an useful concept, but which in certain fields, mainly in the quantum realm, could be substituted by a weaker concept of indiscernibility. This assumption motivates us to look for an interpretation of quantum mechanics based on a non-classical logic, termed non-reflexive, and the corresponding mechanics is called non-reflexive quantum mechanics. (shrink)

String Theory is the result of the conjunction of three conceptually independent elements: (i) the metaphysical idea of a nomological unity of the forces, (ii) the model-theoretical paradigm of Quantum Field Theory, and (iii) the conflict resulting from classical gravity in a quantum world - the motivational starting point of the search for a theory of Quantum Gravity. String Theory is sometimes assumed to solve this conflict: by means of an application of the (only slightly extended) model-theoretical apparatus of (perturbative) (...) Quantum Field Theory, interpreting gravity as the result of an exchange of gravitons, taken here to be dynamical states of the string. But, String Theory does not really solve the conflict. Rather it exemplifies the inadequacy of the apparatus of Quantum Field Theory in the context of Quantum Gravity: After several decades of development it still exists only in an essentially perturbative formulation (with minor non-perturbative extensions and vague ideas with regard to a possible non-perturbative formulation). And, due to its quantum field theoretical heritage, it is conceptually incompatible with central implications of General Relativity, especially those resulting from the general relativistic relation between gravity and spacetime. All known formulations of String Theory are background-dependent. And no physical motivation is given for this conceptual incompatibility. On the other hand, although String Theory identifies all gauge bosons as string states, it was not even possible to reproduce the Standard Model. Instead, String Theory led to a multitude of internal problems - and to the plethora of low-energy scenarios with different nomologies and symmetries, known as the String Landscape. All attempts to find a dynamically motivated selection principle remained without success, leaving String Theory without any predictive power. The nomological unification of the fundamental forces, including gravity, is only achieved in a purely formal way within the model-theoretical paradigm of Quantum Field Theory - by means of physically unmotivated epicycles like higher dimensionality, Calabi-Yau spaces, branes, etc. Finally, the possibility remains that some of the central (implicit) assumptions of String Theory are physically wrong. On the one hand, the idea of a nomological unity of the forces could be simply wrong. On the other hand, even if a nomological unity of all fundamental forces should be realized in nature, the possibility remains that gravity is not a fundamental force, but a residual, emergent and possibly intrinsically classical phenomenon, resulting from a quantum substrate without any gravitational degrees of freedom. (shrink)

This paper is concerned with the relation between two notions: that of two solutions or models of a theory being related by a symmetry of the theory and that of solutions or models being physically equivalent (in the sense of being equally well- or ill-suited to represent any given situation, relative to any reasonable interpretation). A number of authors have recently discussed this relation, some taking an optimistic view, on which there is a suitable concept of the symmetry of a (...) theory relative to which these two notions coincide, others taking a pessimistic view, on which there is no such concept. The present paper arrives at a cautiously pessimistic conclusion. (shrink)