Giordano Bruno and the heresy of many worlds

This paper analyses the importance of Giordano Bruno's belief in many worlds, including the Moon, the planets and the stars, in the context of his trial by the Inquisitions in Venice and Rome. Historians have claimed that this belief was not heretical and therefore was not a major factor in Bruno's trial or execution. On the contrary, by examining neglected treatises on theology, heresies and Catholic canon law, I show that the belief in many worlds was formally heretical. Multiple Christian authorities denounced it. A systematic analysis of the extant primary sources shows that Bruno's belief in many worlds was, surprisingly, of primary importance in his trial and execution. The evidence includes recent and newly discovered primary sources.     

Quantum probability from subjective likelihood: Improving on Deutsch's proof of the probability rule

I present a proof of the quantum probability rule from decision-theoretic assumptions, in the context of the Everett interpretation. The basic ideas behind the proof are those presented in Deutsch's recent proof of the probability rule, but the proof is simpler and proceeds from weaker decision-theoretic assumptions. This makes it easier to discuss the conceptual ideas involved in the proof, and to show that they are defensible.     

Typical worlds

Hugh Everett III presented pure wave mechanics, sometimes referred to as the many-worlds interpretation, as a solution to the quantum measurement problem. While pure wave mechanics is an objectively deterministic physical theory with no probabilities, Everett sought to show how the theory might be understood as making the standard quantum statistical predictions as appearances to observers who were themselves described by the theory. We will consider his argument and how it depends on a particular notion of branch typicality. We will also consider responses to Everett and the relationship between typicality and probability. The suggestion will be that pure wave mechanics requires a number of significant auxiliary assumptions in order to make anything like the standard quantum predictions.     

Subjective probability and quantum certainty

In the Bayesian approach to quantum mechanics, probabilities—and thus quantum states—represent an agent's degrees of belief, rather than corresponding to objective properties of physical systems. In this paper we investigate the concept of certainty in quantum mechanics. Particularly, we show how the probability-1 predictions derived from pure quantum states highlight a fundamental difference between our Bayesian approach, on the one hand, and Copenhagen and similar interpretations on the other. We first review the main arguments for the general claim that probabilities always represent degrees of belief. We then argue that a quantum state prepared by some physical device always depends on an agent's prior beliefs, implying that the probability-1 predictions derived from that state also depend on the agent's prior beliefs. Quantum certainty is therefore always some agent's certainty. Conversely, if facts about an experimental setup could imply agent-independent certainty for a measurement outcome, as in many Copenhagen-like interpretations, that outcome would effectively correspond to a preexisting system property. The idea that measurement outcomes occurring with certainty correspond to preexisting system properties is, however, in conflict with locality. We emphasize this by giving a version of an argument of Stairs [(1983). Quantum logic, realism, and value-definiteness. Philosophy of Science, 50, 578], which applies the Kochen–Specker theorem to an entangled bipartite system.     

Uncertainty and probability for branching selves

Everettian accounts of quantum mechanics entail that people branch; every possible result of a measurement actually occurs, and I have one successor for each result. Is there room for probability in such an account? The prima facie answer is no; there are no ontic chances here, and no ignorance about what will happen. But since any adequate quantum mechanical theory must make probabilistic predictions, much recent philosophical labor has gone into trying to construct an account of probability for branching selves. One popular strategy involves arguing that branching selves introduce a new kind of subjective uncertainty. I argue here that the variants of this strategy in the literature all fail, either because the uncertainty is spurious, or because it is in the wrong place to yield probabilistic predictions. I conclude that uncertainty cannot be the ground for probability in Everettian quantum mechanics.     

Between two worlds: Yamanouchi Shigeo and eugenics in early twentieth-century Japan

This paper explores the eugenic through of Yamanouchi Shigeo (1876-1973), who was trained in plant cytology under the tutelage of botanist and eugenicist John Coulter (1851-1928) in the USA, and later become one of the early and important popularizers of eugenic ideas in Japan. His career demonstrates a direct link between Japanese and US eugenics. Despite his academic training and research at various internationally renowned institutions, numerous publications, and longevity, his life has received little scholarly attention. By the early twentieth century, most biologists in Japan, as in the USA, began accepting Mendelian evolutionary theory and rejecting the Lamarckian notion of inheritance of acquire characteristics. However, Yamanouchi Shigeo's eugenic view represents a paradox: he was a mendelian cytologist sympathetic to Lamarckism. Was his 'nurture'-oriented eugenic view unscientific? is that why he was largely ignored in the history of botany in Japan? This study attempts to answer these questions and to analyse the origins and distinct features of Yamanouchi's eugenic ideas by situating Yamanouchi's eugenic through historically and culturally. After examining his scientific papers, popular writings, and documents of various organizations to which he belonged, I argue that Yamanouchi's 'softer' (or less biologically deterministic) perspective may have reflected the Japanese desire to catch up with the dominant 'race' by using eugenics without accepting permanent inferior status.     

Objective probability and the mind-body relation

Objectiveprobability in quantum mechanics is often thought to involve a stochastic process whereby an actual future is selected from a range of possibilities. Everett's seminal idea is that all possible definite futures on the pointer basis exist as components of a macroscopic linear superposition. I demonstrate that these two conceptions of what is involved in quantum processes are linked via two alternative interpretations of the mind-body relation. This leads to a fission, rather than divergence, interpretation of Everettian theory and to a novel explanation of why a principle of indifference does not apply to self-location uncertainty for a post-measurement, pre-observation subject, just as Sebens and Carroll claim. Their Epistemic Separability Principle is shown to arise out of this explanation and the derivation of the Born rule for Everettian theory is thereby put on a firmer footing.     

Acceptance,values, and probability

This essay makes a case for regarding personal probabilities used in Bayesian analyses of confirmation as objects of acceptance and rejection. That in turn entails that personal probabilities are subject to the argument from inductive risk, which aims to show non-epistemic values can legitimately influence scientific decisions about which hypotheses to accept. In a Bayesian context, the argument from inductive risk suggests that value judgments can influence decisions about which probability models to accept for likelihoods and priors. As a consequence, if the argument from inductive risk is sound, then non-epistemic values can affect not only the level of evidence deemed necessary to accept a hypothesis but also degrees of confirmation themselves.     

An empirical approach to symmetry and probability

We often rely on symmetries to infer outcomes’ probabilities, as when we infer that each side of a fair coin is equally likely to come up on a given toss. Why are these inferences successful? I argue against answering this question with an a priori indifference principle. Reasons to reject such a principle are familiar, yet instructive. They point to a new, empirical explanation for the success of our probabilistic predictions. This has implications for indifference reasoning generally. I argue that a priori symmetries need never constrain our probability attributions, even for initial credences.     

Newton and the classical theory of probability

Summary Probabilistic ideas and methods from Newton's writings are discussed in § 1: Newton's ideas pertaining to the definition of probability, his probabilistic method in chronology, his probabilistic ideas and method in the theory of errors and his probabilistic reasonings on the system of the world. Newton's predecessors and his influence upon subsequent scholars are dealt with in §2: beginning with his predecessors the discussion continues with his contemporaries Arbuthnot and De Moiver, then Bentley. The section ends with Laplace, whose determinism is seen as a development of the Newtonian determinism.An addendum is devoted to Lambert's reasoning on randomness and to the influence of Darwin on statistics. A synopsis is attached at the end of the article.Abbreviations PT abridged Philosophical Transactions of the Royal Society 1665–1800 abridged. London, 1809 - Todhunter I. Todhunter, History of the mathematical theory of probability, Cambridge, 1865 To the memory of my mother, Sophia Sheynin (1900–1970)     

Classical computationalism and the many problems of cognitive relevance

In this paper I defend the classical computational account of reasoning against a range of highly influential objections, sometimes called relevance problems. Such problems are closely associated with the frame problem in artificial intelligence and, to a first approximation, concern the issue of how humans are able to determine which of a range of representations are relevant to the performance of a given cognitive task. Though many critics maintain that the nature and existence of such problems provide grounds for rejecting classical computationalism, I show that this is not so. Some of these putative problems are a cause for concern only on highly implausible assumptions about the extent of our cognitive capacities, whilst others are a cause for concern only on similarly implausible views about the commitments of classical computationalism. Finally, some versions of the relevance problem are not really objections but hard research issues that any satisfactory account of cognition needs to address. I conclude by considering the diagnostic issue of why accounts of cognition in general—and classical computational accounts, in particular—have faired so poorly in addressing such research issues.     

Quantum propensities

This paper reviews four attempts throughout the history of quantum mechanics to explicitly employ dispositional notions in order to solve the quantum paradoxes, namely: Margenau's latencies, Heisenberg's potentialities, Maxwell's propensitons, and the recent selective propensities interpretation of quantum mechanics. Difficulties and challenges are raised for all of them, and it is concluded that the selective propensities approach nicely encompasses the virtues of its predecessors. Finally, some strategies are discussed for reading similar dispositional notions into two other well-known interpretations of quantum mechanics, namely the GRW interpretation and Bohmian mechanics.     

The many encounters of Thomas Kuhn and French epistemology

The work of Thomas Kuhn has been very influential in Anglo-American philosophy of science and it is claimed that it has initiated the historical turn. Although this might be the case for English speaking countries, in France an historical approach has always been the rule. This article aims to investigate the similarities and differences between Kuhn and French philosophy of science or ‘French epistemology’. The first part will argue that he is influenced by French epistemologists, but by lesser known authors than often thought. The second part focuses on the reactions of French epistemologists on Kuhn’s work, which were often very critical. It is argued that behind some superficial similarities there are deep disagreements between Kuhn and French epistemology. This is finally shown by a brief comparison with the reaction of more recent French philosophers of science, who distance themselves from French epistemology and are more positive about Kuhn. Based on these diverse appreciations of Kuhn, a typology of the different positions within the philosophy of science is suggested.