Alberto Cortes, in [1], attempts to show (a) that Leibniz's Principle of The Identity of Indiscernibles (L) is a principle restricted to individuals (as distinct from a class of entities Cortes takes to be non-individuals), and (b) that photons (light quanta) appear to violate L (since they don't obey Pauli's Exclusion Principle). L is stated by Leibniz as “no two substances are completely similar, or differ solo numero.” In second-order quantification theory with identity L becomes:

In a recent paper, William K. Goosens (1978) objects to the arguments I set out some time ago attacking the logical empiricist analysis of reduction as applied to genetics (Hull 1972, 1973, 1974, 1976a). In these works I did not argue against the claim that Mendelian genetics was being reduced to molecular biology. Nor did I conclude, as Goosens asserts, that in the case of genetics, “reduction is insignificant” (p. 93). To the contrary, I repeatedly stated that, “given our pre-analytic intuitions about reduction,” the reduction of Mendelian to molecular genetics “is a case of reduction, a paradigm case” (Hull 1974 p. 44). And in agreement with Kenneth Schaffner (1967) I argued that reduction “in some very important, pre-analytic sense has taken place and is taking place in genetics” (Hull 1973, p. 634). The target of my objections to reduction in genetics was not “reduction” in some pre-analytic sense. Nor was it the various explications which have appeared since. Rather it was the notion of theory reduction set out a generation ago by such logical empiricists as Ernest Nagel (1961), The particular version of this analysis which I chose to attack was that presented by Schaffner (1967, 1969); for Schaffner's later views, see his (1974, 1976, 1977). I chose Schaffner's explication to attack because I thought it was the best of its kind and because it was the only defense of the logical empiricist analysis at the time which used genetics as one of its chief examples. Contrary to Goosens' assumption, in criticizing Schaffner's explication, I did not thereby “endorse” it (p. 82).

The main appeal of the currently popular “bootstrap” account of confirmation developed by Clark Glymour is that it seems to provide an account of evidential relevance. This account has, however, had severe problems; and Glymour has revised his original account in an attempt to solve them. I argue that this attempt fails completely, and that any similar modifications must also fail. If the problems can be solved, it will only be by radical revisions which involve jettisoning bootstrapping's basic approach to theories. Finally, I argue that there is little reason to think that even such drastic modifications will lead to a satisfactory account of relevance.

Gauge theories are theories that are invariant under a characteristic group of “gauge” transformations. General relativity is invariant under transformations of the diffeomorphism group. This has prompted many philosophers and physicists to treat general relativity as a gauge theory, and diffeomorphisms as gauge transformations. I argue that this approach is misguided.

Causal decision theory produces decision instability in cases such as Death in Damascus where a decision itself provides evidence concerning the utility of options. Several authors have proposed ways of handling this instability. William Harper (1985 and 1986) advances one of the most elegant proposals. He recommends maximizing causal expected utility among the options that are causally ratifiable. Unfortunately, Harper's proposal imposes certain restrictions; for instance, the restriction that mixed strategies are freely available. To obtain a completely general method of handling decision instability, I step outside the confines of pure causal decision theory. I introduce a new kind of backtracking expected utility and propose maximizing it among the options that are causally ratifiable. In other words, I propose a hierarchical maximization of (1) conditional causal expected utility and (2) the new backtracking expected utility. I support this proposal with some intuitive considerations concerning the distinction between optimality and conditional optimality. And I prove that the proposal yields a solution in every finite decision problem.

The question as to the existence of laws in history has frequently been discussed. A new discussion may yet be useful, since some misconceptions based on incorrect comparisons with the natural sciences have been brought forward by both advocates and opponents of historical laws. We shall try to clarify the problem by applying a few ideas familiar to physicists and astronomers to the conditions peculiar to history. Physics is the most mature of all empirical sciences as to method. In physics the law-concept has been used for three hundred years. It may be assumed, therefore, that most of the difficulties in its application to other fields have their physical counterpart and can be clarified most easily with the help of physical concepts. A few preliminary examples of historical laws will be given towards the end of the article.

There is a fairly long-standing distinction between what are called the ideographic as opposed to nomothetic sciences. The nomothetic sciences, such as physics, offer explanations in terms of the laws and regular operations of nature. The ideographic sciences, such as natural history (or, more controversially, evolutionary biology), cast explanations in terms of narratives. This article offers an account of what is involved in offering an explanatory narrative in the historical (ideographic) sciences. I argue that narrative explanations involve two chief components: a possibility space and an explanatory causal mechanism.

In 1894, William Bateson objected to the terms “heredity” and “inheritance” in biology, on grounds of contamination with misleading notions from the everyday world. Yet after the rediscovery of Mendel's work in the spring of 1900, Bateson promoted that work as disclosing the “principles of heredity.” For historians of science, Bateson's change of mind provides a new angle on these terms at a crucial moment in their history. For philosophers of science, the case can serve as a reminder of the potential of Putnam's hypothesis of a division of linguistic labor for analyzing the semantic lives of scientific kind terms.

A primary goal of quantum computer science is to find an explanation for the fact that quantum computers are more powerful than classical computers. In this paper I argue that to answer this question is to compare algorithmic processes of various kinds and to describe the possibility spaces associated with these processes. By doing this, we explain how it is possible for one process to outperform its rival. Further, in this and similar examples little is gained in subsequently asking a how-actually question. Once one has explained how-possibly, there is little left to do.

This paper explores some connections between competing conceptions of scientific laws on the one hand, and a problem in the foundations of statistical mechanics on the other. I examine two proposals for understanding the time asymmetry of thermodynamic phenomenal: David Albert's recent proposal and a proposal that I outline based on Hans Reichenbach's “branch systems”. I sketch an argument against the former, and mount a defense of the latter by showing how to accommodate statistical mechanics to recent developments in the philosophy of scientific laws.

Nancy Cartwright's charge against horizontal reductionism leads to a claim about how the world is, namely “dappled.” By proposing a simple thought-experiment, I show that Cartwright's division of the world into “nomological” machines and “messy” systems for which no law applies is meaningless. The thought-experiment shows that for a system, having the property of being a nomological machine depends on what kind of questions you ask about it. No metaphysical conclusion about the world being unruly or not can be drawn from a division that is question-dependent. Moreover, I argue that this predicament undermines Cartwright's attempt to provide an illustration of how bad metaphysics of science translates into bad scientific methodologies and policies.

Rayleigh and Ramsay discovered the inert gas argon in the atmospheric air in 1895 using a carefully designed sequence of experiments guided by an informal statistical analysis of the resulting data. The primary objective of this article is to revisit this remarkable historical episode in order to make a case that the error-statistical perspective can be used to bring out and systematize (not to reconstruct) these scientists't resourceful ways and strategies for detecting and eliminating error, as well as dealing with Duhemian ambiguities and underdetermination problems as they arose in the context of their local research settings.

Samir Okasha argues that clade selection is an incoherent concept, because the relation that constitutes clades is such that it renders parent-offspring (reproduction) relations between clades impossible. He reasons that since clades cannot reproduce, it is not coherent to speak of natural selection operating at the clade level. We argue, however, that when species-level lineages and clade-level lineages are treated consistently according to standard cladist commitments, clade reproduction is indeed possible and clade selection is coherent if certain conditions obtain. Despite clade selection's logical coherence, however, we share some of Okasha's pessimism. Whether or not clades are a unit of selection is ultimately a question of empirical support and theoretical import.

This article defends the following claims. First, for patterns exhibited in empirical data, there is no criterion on which to demarcate patterns that are physically significant and patterns that are not physically significant. I call a pattern physically significant if it corresponds to a structure in the world. Second, all patterns must be regarded as physically significant. Third, distinct patterns must be regarded as providing evidence for distinct structures in the world. Fourth, in consequence, the world must be conceived as showing all possible structures.

Ernst Mayr has criticised the methodology of population genetics for being essentialist: interested only in “types” as opposed to individuals. In fact, he goes so far as to claim that “he who does not understand the uniqueness of individuals is unable to understand the working of natural selection” (1982, 47). This is a strong claim indeed especially since many responsible for the development of population genetics (especially Fisher, Haldane, and Wright) were avid Darwinians. In order to unravel this apparent incompatibility I want to examine the possible sources and implications of essentialism in this context and show why the kind of mathematical analysis found in Fisher's work is better seen as responsible for extending the theory of natural selection to a broader context rather than inhibiting its applicability.

Recently, macroscopic accounts of chemical kind individuation have been proposed as alternatives to the microstructural essentialist account advocated by Kripke, Putnam, and others. These accounts argue that individuation of chemical kinds is based on macroscopic criteria such as reactivity or thermodynamics, and they challenge the essentialism that grounds the Kripke-Putnam view. Using a variety of chemical examples, I argue that microstructure grounds these macroscopic accounts, but that this grounding need not imply essentialism. Instead, kinds are individuated on the basis of similarity of reactivity between substances, and microstructure explains similarity of reactivity.

Given the impressive success of environment-induced decoherence (EID), nowadays no interpretation of quantum mechanics can ignore its results. The modal-Hamiltonian interpretation (MHI) has proved to be effective for solving several interpretative problems, but since its actualization rule applies to closed systems, it seems to stand at odds with EID. The purpose of this article is to show that this is not the case: the states einselected by the interaction with the environment according to EID (the elements of the “pointer basis”) are the eigenvectors of an actual-valued observable belonging to the preferred context selected by the MHI.

In the philosophy of science, abstraction has usually been analyzed in terms of the interface between our experience and the design of our concepts. The often implicit assumption here is that such interface has a definite identifiable and universalizable structure, determining the epistemic correctness of any abstraction. Our claim is that, on the contrary, the epistemic grounding of abstraction should not be reduced to the structural norms of such interface but is also related to the constraints on the cognitive processes of specific abstractions. This suggests that we should understand abstraction as embodied in different kinds of abstraction practices.

During my recent work on machine translation (3), I have come across many problems of a linguistic nature that should be of general methodological interest. Some of these problems have never been treated extensively before. Others that have been discussed previously appear now in a different and rather interesting light.

In a recent article P. Henle gave an analysis of the notion of emergence. His inquiry deals with what he calls, quite appropriately, the emergence of characteristics. Such emergence, that is, the emergence of qualities and relations is undoubtedly the primary connotation of the term, and I feel that Henle has been very successful in clarifying it. The purpose of the present paper is to discuss in some detail one special aspect of Henle's analysis. This is done because the precise formulation of this particular aspect sheds light on the notion of elementarism. And the opposite of this notion, holism or organicism, belongs undoubtedly to the variety of fused and confused meanings the idea of emergence has come to cover.