The Duhem-Quine concept of the underdetermination of theory by evidence has perhaps been the most crucial influence on philosophy of science during recent decades. It is a concept that has brought together metaphysical and epistemological issues that had been sundered into a mass of non-communicating specialisms in the decline of positivism. It has given birth to a new spectrum of comprehensive theories about the nature of science, ranging from scepticism and historicism, to a near-Aristotelian revival of realism, essentialism and necessitarianism. By way of its implications for the indeterminacy of truth-values, it has revived discussion of theories of truth, meaning and realism in relation to science, and philosophers of science have gone back to the pre-positivist authors - Frege, Peirce, Mach, Poincare, Duhem – for their pioneering arguments on sense and reference, correspondence and consensus, realism, instrumentalism and conventionalism.

I shall argue in this paper that although much attention has been paid to causal chains and common causes within the literature on probabilistic causality, a primary virtue of that approach is its ability to deal with cases of multiple causation. In doing so I shall try to indicate some ways in which contemporary sine qua non analyses of causation are too narrow Cand ways in which probabilistic causality is not) and refine an argument by Relchenbach designed to provide a basis for the asymmetry of causation.

In his contribution to this symposium (Salmon 1981) Professor Salmon has emphasized the central role played by processes and interactions in causality. Whereas his discussion of common causes naturally has a futuristic orientation using causal fans of the type given in Fig. 1.,

I shall be rather more backwards-looking and concentrate on the advantages that probabilistic causation possesses for the analysis of multiple causes of the type in Fig. 2.

One component of a viable account of scientific inquiry is a defensible conception of scientific problems, i.e., a conception which meets logical demands and which also fits or explains basic “data” arising from the history of that inquiry, including an account of how problems arise. In this paper I shall argue that three standard empiricist models of problems—essentially the logical positivist and Popperian views—satisfy neither the historical requirements nor even the logical conditions (except, weakly, in the case of Popper). These failures are instructive, however. They represent steps toward the solution of the “problem” problem—the problem of developing a model of problems rich enough to account for the data. In the weakest sense (which is all I need), ‘accounting for’ a datum means explaining how that aspect of scientific inquiry is possible. I shall not have space here to consider promising recent work on problems by Laudan (1977) and others.

Kuhn (1962), Lakatos (1978) and Laudan (1977) all subscribe to a view of science which admits the existence of large scale entities differing from theories. Kuhn called these entities ‘paradigms’, Lakatos called them ‘research programs’ and Laudan calls them ‘research traditions’. These entities are distinguished from theories by their historical durability and the unique manner in which they succeed one another. The history of science may be described as a succession of eras during each of which one (or more) of these entities was dominant. During its era of dominance one of these entities may support several incompatible theories which replace one another successively but share certain common features. These features may be (part of) a common ontology, a common set of epistemological standards employed in gathering observational evidence, or common methodological or conceptual directives employed in solving new scientific problems. Although theories may change, these features (or some of these features) do not, instead they are the province of the large scale entity.

Empiricists are notoriously suspicious of causes. They have not been equally wary of laws. Hume set the tradition when he replaced causal facts with facts about generalizations. Modern empiricists do the same. But nowadays Hume's generalizations are the laws and equations of high level scientific theories. On current accounts, there may be some question about where the laws of our fundamental theories get their necessity, but it is no question that these laws are the core of modern science. Bertrand Russell is well known for this view: “The law of gravitation will illustrate what occurs in any exact science … . Certain differential equations can be found, which hold at every instant for every particle of the system … . But there is nothing that could be properly called “cause” and nothing that could be properly called “effect” in such a system.”

If science is essentially a problem-solving activity, it stands to reason that a good part of the rationale behind the development and growth of new scientific fields (or subfields) is the generation of problem-solutions. I should like to argue that the origin and, especially, the development of new scientific fields is primarily a research procedure for solving existing unsolved problems and generating and solving new unsolved problems. By a scientific field I have in mind the following:

A standard picture of causality has been around at least since the time of Hume. The general idea is that we have two (or more) distinct events which bear some sort of cause-effect relation to one another. There has, of course, been considerable controversy regarding the nature of both the relation and the relata. It has sometimes been maintained, for instance, that facts or propositions (rather than events) are the sorts of entities which can constitute the relata. It has long been disputed whether individual events or only classes of events can sustain cause-effect relations. The relation itself has sometimes been taken to be that of sufficient condition, sometimes necessary condition, or perhaps a combination of the two. Some authors have even proposed that certain sorts of statistical relations constitute causal relations.

In 1886 Friedrich Nietzsche noted the following basic error in the philosophies of his day, ”…to place the goal in the herd and not in single individuals! The herd is a means, no more! But now one is attempting to understand the herd as an individual and to ascribe to it a higher rank than to the individual—profound misunderstanding!!! Also to characterize that which makes herdlike, sympathy, as the more valuable side to our nature!” (Nietzsche 1901, p. 403).

The recent flap over sociobiology has stemmed largely from the fear that biology is being used to justify a Nietzschean view of human societies, as if the chief good in human relations must be basically selfish, as if apparently altruistic behavior is fundamentally hypocritical. From Darwin to the present, biologists have blithely attributed the presence and persistence of all sorts of traits, including behavioral traits, to the “good of the species”.

In the present work, I discuss the interpretation of quantum mechanics (QM) from the viewpoint of quantum logic (QL). I regard the objects of QL to be the possible (accidental) properties that can be ascribed to a quantum system SYS. The basic idea is that, at any given moment t, SYS actualizes some properties, but not others. The micro-state of SYS at time t is identified with the set of all properties that SYS actualizes at time t.

One thing an interpretation of QM is supposed to do, I believe, is delineate the admissible quantum micro-states. Since the characterization of quantum micro-states is intimately related to the characterization of quantum logical consistency, the interpretation of QM is intimately tied to the interpretation of QL.

Two kinds of interpretations are discussed. Strict interpretations are based on the assumption that the properties of a system are individuated by the projection operators on the associated Hilbert space.

The units of selection problem, as it is discussed within evolutionary theory, recapitulates some important elements in the dispute between methodological holism and methodological individualism. Holism and individualism have for a long time occupied favored positions in the stable of old warhorses owned and operated by philosophers of social science. These particular old warhorses are thought by many to be in retirement, although there is less than universal agreement about whether holism or individualism won the battle. Part of the point I will make about group versus individual selection is that biologists, would do well not to emulate certain aspects of the holism/individualism controversy.

There is no such thing as “The Quantum Logical Interpretation of Quantum Mechanics”. Rather, there is a cluster of interpretations, all of which can be described as “quantum logical”. Here I provide a general framework for discussing interpretations of this kind, and then locate various suggestions within it. The presentation owes much to van Fraassen (see, in particular, van Fraassen 1974 ); his “modal interpretation” is one of those I discuss, along with those of Jauch, Putnam and Kochen. I begin by rehearsing some orthodox quantum theory.

Within quantum mechanics we deal with a set 0 of measurable quantities, or observables (position, momentum, components of spin and so on). Experiment can determine the value of an observable for a given system: the values so determined will be real numbers. A maximal amount of information about what the result would be for a given system, whatever experiment we chose to perform on it, is available once we know the state of the system.

The dominant view among evolutionary biologists today is that the gene is the only unit of selection. According to this view, larger units are too unstable in evolutionary time to act as units of selection. Chromosomes are broken up by sexual recombination. At the level of the individual organism, phenotypes pass on genes, but (it is claimed!) last themselves only one generation. Genotypes of individuals, collections of chromosomes, are rearranged by Mendelian independent assortment in sexual reproduction and so also persist for only one generation. Groups of individuals are still more ephemeral, or so we are told.

All of these points are argued at length by George C. Williams in his book Adaptation and Natural Selection which, since its publication in 1966, has been the watershed for the rise to dominance of this reductionistic vision of evolutionary theory.

There is no more popular pastime in the literature of the philosophy of biology than analyzing the concept of species. This is partly due to the fact that the concept is such a prominent one in presentations of evolutionary theory. It is also a result of the fact that philosophers and biologists have struggled without a great deal of success to formulate a definition of species that would be acceptable for all the diverse purposes of the biological sciences.

For some time, philosophers of biology assumed that, whatever problems of definition and explication exist regarding the concept of a species, the ontological status of the concept was certain. Species have long been viewed as classes. Indeed, they have been viewed as paradigmatic examples of classes of a special variety. Since the traits of organisms vary from creature to creature as well as from generation to generation, a special set of properties must be used to group or aggregate organisms into species.

The Darwinian theory of evolution through natural selection is beyond a doubt an extremely well established theoretical edifice that satisfies any reasonable conceptual and empirical criterion of scientific respectability. It is a body of well confirmed nomological generalizations with great explanatory and predictive power. And yet the most accessible account of the relation between this theory, its competitors and the empirical evidence seems seriously defective in its account of these relations. Indeed, it may seem so defective as to leave the question open, not whether the theory of natural selection is well confirmed (this cannot be doubted), but exactly what sort of evidence does confirm it and via what bridge principles. The account of the matter which I have described as most accessible (in the philosophy of science at any rate), and yet seriously bedeviled is to be found in Michael Ruse's otherwise excellent introduction to the Philosophy of Biology (Ruse 1973 ).

When Max Born introduced his statistical interpretation of wave mechanics in mid-1926, the reactions were mixed. His most recent collaborator, Pascual Jordan, was delighted; his former assistant, Werner Heisenberg, was horrified. The interpretation served as grist for Neils Bohr's philosophical mill. For Bohr's former collaborator, John Slater, it inspired a strange hybrid interpretation, a sort of statistical version of Schrödinger's electrodynamic model. What was the interpretation that engendered these varied reactions? Neither Born nor most of his contemporaries saw in it anything that even suggests the interpretation that we now associate with his name. Rather, it was another former assistant of Born's, Wolfgang Pauli, with eyes as sharp as his tongue, who saw in Born's work the idea that |Ψ(q)| represents the probability distribution for position.