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.

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.”

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”.

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.

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.

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.

Why does Bohr nowhere discuss the projection postulate? He has the courtesy to cast at least a few disparaging words at some other notions for which he has no use, such as quantum logic. But he will not even admit the projection postulate as a subject for discussion. Another way to raise the puzzle is to point out that, although Bohr has a lot to say about measurement, he won't even recognize the existence of what has come to be called the “problem of measurement”.

I have exaggerated slightly. We have one relevant comment, in the report of the discussion after Bohr's talk at the 1938 Warsaw conference:

When the Unity of Science movement organized, Niels Bohr was listed as the first member of the Advisory Committee. He contributed a one page paper to Volume One of the International Encyclopedia of Unified Science (Bohr 1938). This paper stressed, but did not explain, the idea that to bring out the proper unity of science it is necessary to analyze the presuppositions underlying the unambiguous application of even our most elementary concepts. Since this rather trivial paper was the only contribution to the movement Bohr made, he might seem to have little interest in the unity of science.

The opposite was the case. Bohr thought that his explanation of the unity proper to physics was one of his most basic, and certainly his most misunderstood, contributions to science. Yet, he thought that he never succeeded in making his position intelligible to professional philosophers.

Mental imagery has been on the defensive for the last fifty years. Philosophers have argued that talk of mental images invites systematic confusion, that such talk is at best metaphorical, and that it consequently creates only an unfortunate illusion of explanation when it is taken literally. Such a prioristic objections ought to carry less weight in the case of experimental studies of imagery since empirical findings are likely to supply nonmetaphorical content where it is needed. Nevertheless, the same sorts of criticism have been put forward against experimental efforts. Added to this is a suspicion that mental imagery is not compatible with a strictly computational account of mental processes and hence it is out of step with the most promising research occurring in cognitive psychology. So, even in the case of experimental studies, there is a presumptive burden of argument on those who take mental imagery seriously.

Although we all speak of “representation”, philosophers and psychologists often have quite different referents for the term. Among philosophers, “representation”, or “a representation”, usually refers to a picture of some sort; and concerns with resemblance, realism, abstraction, and the like are prominent (Goodman 1968). Psychologists and some philosophers accept the term more broadly, and by representation mean something like symbol— that is, some mark that stands for, denotes, or represents something else (Howard 1980). I shall use the word in this latter way.

Goodman's treatment of symbols and so, willy-nilly, of representation, is the most sophisticated we háve. He has been concerned largely with reference—with what symbols may mean—and expresses the concern with a theory of the structure and function of symbols.

The public image of private imagery is showing signs of a comeback. Not only does it again seem legitimate to talk about “having” images, there has been a tremendous revival of interest in the role of imagery in all aspects of cognition. But while the experimental work on imagery has been progressing nicely, there is little agreement over how best to interpret the empirical results. The newly gathered data not only has not convinced everyone of the importance of imagery, it has spawned a whole new generation of critics who are sure that imagist explanations of cognition are without merit. These critics generally do not deny that people experience images; rather they deny the significance of these phenomena for psychological theory. Some go so far as to maintain that the very notion of an imagist explanation is in principle misguided.

For more than a century social scientists and philosophers of social science have argued about whether or not the ontology and methodology for inquiry in the physical sciences is appropriate to capture adequately the regularities of social life and their underlying causal determinants. The issue arises because of the prima facie fact that human actions are structured not only by the laws governing the behavior of physical matter, but also by intentional systems—that is, by culture-wide systems of concepts, rules, conventions and beliefs, and by individual systems of perceptions, motives, and goals arrived at within these cultural systems. Consequently, it is not possible either to identify or to classify human actions apart from this intentional dimension within which human action occurs. Whether, and how, this difference in the nature of the subject matter of social inquiry requires “deviating” from the “logic” of the natural sciences then becomes the substance of the dispute.

In recent years, historicist understandings of science have come to prominence in philosophy of science and philosophy of social science. These approaches have been credited with putting forward a persuasive case that social scientific theories, like societies, are themselves historical entities. (Laudan 1979, p. 43; McMullin 1979, p. 57). Historicist studies have forced a re-evaluation of a number of important issues, among them the question of how methodologies are to be evaluated, and questions about how the relation of theory to observation is to be understood. (Laudan 1979, pp. 47-48).

Despite their successes, however, historicist approaches fail in two important ways: 1) they are unable to solve the problems posed by methodological relativism, and 2) they fail to go beyond treating theories as personages to the important questions of how these theories arise from particular social structures.

This paper deals briefly with two questions which I have discussed elsewhere (Koertge 1981 and forthcoming):

1. a) If all scientists were perfect Popperians (i.e., absolutely scrupulous with respect to methodology), how much influence could their backgrounds have? I include under background: the individual's “background knowledge” (in Popper's sense), psycho-sexual upbringing, class origins or identification, metaphysics, and ideology. This is a rather mixed bag and I hope the context will make clear whether it is primarily the person's values which are influential or his/her prescientific beliefs.

2. b) Having argued that it is possible for background to play a role, I then ask whether the ideals of feminism suggest the need for a new methodology and epistemology for science. I will comment in particular on Harding's paper in this volume.

Within the lore of nearly every scientific theory, among the facts, laws, theorems, and such that constitute the “truths” it expresses, are one or more principles. Physics textbooks, I know, usually mention them at the beginning, or during some interlude given over to general remarks or speculation. As examples, the uncertainty principle and correspondance principle of quantum mechanics come to mind (see, e.g., Messiah 1960). And associated with the general theory of relativity, which is particularly rich in principles, are a principle of general covariance, a principle of equivalence (or two), Mach's principle, and a general principle of relativity (see, e.g., Misner, Thome, and Wheeler 1973).

Where do principles come from? Generally, as I said, they are supposed to be “truths” about the working of the world: observations and experiments are appealed to as their sources. But this doesn't distinguish them from facts and laws.

In the 1950's and 60's there arose a plethora of claims that the structure of evolutionary theory was intrinsically different from the structures of the theories of physics—and thus from the structure that philosophers of science claimed to be the structure of scientific theories. There were claims:

1. 1) that evolutionary theory had no laws (Smart 1963);

2. 2) that evolutionary concepts were so peculiar that their definitions violated the ordinary standards for definitions (Beckner 1959);

3. 3) that evolutionary theory was not axiomatizable (Beckner 1959);

4. 4) that evolutionary theory made no falsifiable predictions (Scriven 1959, Manser 1965, Smart 1963);

5. 5) that evolutionary biology relied on teleological explanations which violated the deductive-nomological explanation form (Hempel 1965); and

6. 6) that evolutionary biology made significant use of narrative explanations which also violated the deductive-nomological explanation form (Goudge 1961)