Kripke-style models with two accessibility relations, one intuitionistic and the other modal, are given for analogues of the modal systemK based on Heyting's prepositional logic. It is shown that these two relations can combine with each other in various ways. Soundness and completeness are proved for systems with only the necessity operator, or only the possibility operator, or both. Embeddings in modal systems with several modal operators, based on classical propositional logic, are also considered. This paper lays the ground for (...) an investigation of intuitionistic analogues of systems stronger thanK. A brief survey is given of the existing literature on intuitionistic modal logic. (shrink)
Milan, David While esteemed Christian apologist C.S. Lewis ruefully puzzled over The Problem of Pain, the theologians invented their own word - 'theodicy' - to describe the futile attempts (to date) to resolve monotheism's conundrum - that of an omnipotent, all-loving deity magisterially presiding over a world in which widespread evil is so pervasive. And what a mind bender this is!
Milan, David An atheist and his christian friend are engaged in cordial conversation. The latter is taken aback and is rather indignant when his atheist friend declaims, 'On this question of the existence of god I believe that our respective positions are much closer than you imagine'. The Christian's firm riposte is that, by definition, such a harmony of viewpoints is impossible. Unfazed, his non-believing friend offers a thoughtful defence of his claim. He begins, 'You know that, since time (...) immemorial, humankind has taken unto itself all manner of gods, and that almost all of these tribal deities have long since vanished into obscurity.'. (shrink)
Evidence for instances of astrophysical 'fine tuning' (or 'coincidences') is thought by some to lend support to the design argument (i.e. the argument that our universe has been designed by some deity). We assess some of the relevant empirical and conceptual issues. We argue that astrophysical fine tuning calls for some explanation, but this explanation need not appeal to the design argument. A clear and strict separation of the issue of anthropic fine tuning on one hand and any form of (...) Eddingtonian numerology and teleology on the other, may help clarify arguably the most significant issue in the philosophy of cosmology. (shrink)
Synaesthesia is a condition in which one type of stimulation evokes the sensation of another, as when the hearing of a sound produces photisms, i.e. mental percepts of colours. R is a 20 year old colour blind subject who, in addition to the relatively common grapheme-colour synaesthesia, presents a rarely reported cross modal perception in which a variety of visual stimuli elicit aura-like percepts of colour. In R, photisms seem to be closely related to the affective valence of stimuli and (...) typically bring out a consistent pattern of emotional responses. The present case study suggests that colours might be an intrinsic category of the human brain. We developed an empirical methodology that allowed us to study the subject's otherwise inaccessible phenomenological experience. First, we found that R shows a Stroop effect (delayed response due to interference) elicited by photisms despite the fact that he does not show a regular Stroop with real colours. Secondly, by manipulating the colour context we confirmed that colours can alter R's emotional evaluation of the stimuli. Furthermore, we demonstrated that R's auras may actually lead to a partially inverted emotional spectrum where certain stimuli bring out emotional reactions opposite to the normal ones. These findings can only be accounted for by considering R's subjective colour experience or qualia. Therefore the present paper defends the view that qualia are a useful scientific concept that can be approached and studied by experimental methods. (shrink)
À la suite du printemps arabe, nombre de citoyens des démocraties occidentales se sont regroupés sur les places publiques pour afficher ouvertement leur indignation par rapport aux dérives du système démocratique affaibli par un pouvoir financier grandissant. Ce texte retrace le chemin qui a amené les auteurs à investir l’espace public. Pensée comme un espace inclusif où le citoyen peut se réapproprier son pouvoir par la discussion, l’écoute et l’autoéducation au vivre ensemble, l’occupation se définit d’abord par sa pratique. Ce (...) sont en effet des moyens alternatifs, et novateurs qui sont mobilisés pour faire face à la crise environnementale, politique, économique et sociale que le système économique capitaliste néolibéral exacerbe. De nombreux outils : réseau social international, réunions, bulletin hebdomadaire, actions, émissions de radios, créés durant l’occupation permettent aujourd’hui au mouvement de se renouveler dans le but de redonner légitimité et force au réel pouvoir politique démocratique. (shrink)
A new probability interpretation of interference phenomena in the double-slit experiment is proposed. It differs from the standard interpretation (based on elementary events happening in complementary, mutually exclusive setups—arrivals of waves to the screen when one of the slits is closed) which encounters the “paradox” that the law of total probability is violated. This new interpretation is free of such difficulties and paradoxes since it is based on compatible elementary events (events happening in the same setup in which happenall events (...) considered—arrivals of quantons to the screen when both slits are open). Quantum objects—quantons—possess simultaneously particle and wave properties. Compatible statistical interpretation synthesizes in a consistent way the superposition principle for waves and the law of total probability applied to compatible events. Such synthesis is a theoretical expression of de Broglie's observation, now fully confirmed by experiments, that the interference fringes obtained on a photographic plate result from an infinite number of tiny local spots which display arrival of quantons, while the set of fringes is a statistical effect of the wave aspect. (shrink)
We use joint probabilities to analyze the EPR argument in the Bohm's example of spins.(1) The properties of distribution functions for two, three, or more noncommuting spin components are explicitly studied and their limitations are pointed out. Within the statistical ensemble interpretation of quantum theory (where only statements about repeated events can be made), the incompleteness of quantum theory does not follow, as the consistent use of joint probabilities shows. This does not exclude a completion of quantum mechanics, going beyond (...) it, by a more general theory of single events, using hidden variables, for example. (shrink)
The study of the motion of the magnetic top—a classical spherical top which carries magnetic moment proportional to its angular momentum, is motivated and inspired by the quantum mechanical relation between spin angular momentum and spin magnetic moment. Inversely, the magnetic top, taken to be the classical model of quantum spin, implies the description of spin states by probability amplitudes of the top orientation angles, instead of by Pauli spinors. This opens new possibilities for the interpretation of many interesting spin (...) experiments which serve as tests of basic principles of quantum mechanics and of the postulates of the quantum theory of measurement. (shrink)
The new techniques and ideas in quantum interferometry with neutrons, photons, atoms, electrons, and Bose condensates that fluorished in the last two decades have influenced in a decisive way the thinking and the research in the foundations and interpretation of quantum mechanics. The controversies existing among different schools on the reality of matter waves of quantum theory, the postulates of quantum measurement theory, and the (in)completeness of quantum mechanics have to be approached now in a new way. Our argumentation follows (...) the spirit of the Paris school. (shrink)
A compatible statistical interpretation of a wave packet is proposed. De Broglian probabilities which unite wave and particle features of quantons are evaluated for free wave packets and Jor a superposition of wave packets. The obtained expressions provide a very plausible and physically appealing explanation of coherence in apparently incoherent beams and of the characteristic modulation of the momentum distribution, found recently in neutron interferometry combined with spectral filtering. Certain conclusions about dualism and objectivity in quantum domain are also derived.
During the past few years,organic dairy farming has grown dramatically inDenmark. Consequently, an increasing number ofpeople are encountering this method ofproduction for the first time. Amongst these,many veterinarians have suddenly had to dealwith organic herds in their home district, and,meeting examples of poor animal welfare, theyhave recently started to express some concerns.
In a variety of synaesthesia, photisms result from affect-laden stimuli as emotional words, or faces of familiar people. For R, who participated in this study, the sight of a familiar person triggers a mental image of "a human silhouette filled with colour". Subjective descriptions of synaesthetic experiences induced by the visual perception of people's figures and faces show similarities with the reports of those who claim to possess the ability to see the aura. It has been proposed that the purported (...) auric perception may be easily explained by the presence of a specific subtype of cross-modal perception. We analyse the subjective reports of four synaesthetes who experience colours in response to human faces and figures. These reports are compared with descriptions of alleged auric phenomena found in the literature and with claims made by experts in esoteric spheres. The discrepancies found suggest that both phenomena are phenomenologically and behaviourally dissimilar. (shrink)
Using the time-dependent wave function we have studied the properties of the atomic transverse motion in an interferometer, and the cause of the non-classical behavior of atoms reported by Kurtsiefer, Pfau, and Mlynek [Nature 386, 150 (1997)]. The transverse wave function is derived from the solution of the two-dimensional Schrödinger's equation, written in the form of the Fresnel–Kirchhoff diffraction integral. It is assumed that the longitudinal motion is classical. Comparing data of the space distribution and of the transverse momentum distribution (...) in interferometers with one and two open slits, it follows that the atomic motion is influenced by the atomic matter wave and violates the laws of classical mechanics. However, the negative values of Wigner's function should not be taken as evidence that the atoms in an interferometer violate the classical statistical law of the addition of positive probabilities. This inference follows from the comparison of properties of Wigner's function and of the de Broglian probability density in phase space. (shrink)
Milan Kundera's first major novel, The Joke, was written in 1961-1965, before he made the decision to leave Czechoslovakia and take up residency as a political exile in France.1 With a few noteworthy exceptions, critics of the work focused on its political message in a Cold War context. This was easy to do: its plot revolves around an avid young Czech communist (Ludvik), who writes an ironic postcard to his overly earnest girlfriend while she is away at a political (...) training camp. The year is 1950, and among intellectuals, enthusiasm for a new era of Soviet-mediated socialism is a genuine response to the chaotic disintegration of old certainties after the Nazi occupation of the country. Ludvik is dedicated to the .. (shrink)