When reading the papers of Solomon, Thagard and Goldman, I observed their framing doing considerable explicit and implicit work. Framing, a visual metaphor, stimulated me to respond with images of one kind or another. These should allow readers to visualize more issues and propositions than an argumentive format could have pinned down in the limited space available.

Figure 1 conveys how the three papers seem to me to frame the issue of integrating the cognitive and social: Scientists’ beliefs are the focal phenomena, within three nested boxes of factors surrounding them: thinking (reasoning etc.); cognition (information input and processing); and social (interaction among agents). (The other objects and lines will be explained in due course.) These factors are referred to as influences, something outside that gets into beliefs (1). The authors then argue about which set of influences is strongest or how to think about the factors “intermingling,” “overlapping,” “interacting.”.

When the Neyman-Pearson approach to the testing of statistical hypotheses was introduced in the 1930's and 1940's it was presented with an accompanying philosophy of science. Jerzy Neyman held a strong form of pragmatism. He sought not just to model scientific decision on practical decision, but in a sense to reduce it to practical decision. Neyman-Pearson techniques are used to compare hypotheses in the light of experimental data, and they contain an asymmetry, in that one hypothesis—the “null”—typically gets the benefit of the doubt. For Neyman, the choice of which hypothesis gets this benefit is governed by behavioral considerations. When presented as an account of testing in science this claim was met with vigorous resistance.

Though the philosophy was controversial, the methods became standard. Philosophers and statisticans have produced alternative interpretations of many distinctive features of these tests. But they are not the only ones who have had to give a new rationale for Neyman-Pearson methods.

The Human Genome Project (henceforth HGP) arouses strong feelings. Enthusiasts view it as the culmination of the extraordinary progress of molecular biology during the past half century and as the beginnings of a revolutionized biology and medicine (Gilbert 1992, Caskey 1992). Detractors charge that it is wasteful, misguided, and pregnant with possibilities for social harm (Lewontin 1992, Hubbard and Wald 1993). In a short paper it is plainly impossible to explore all the sources of disagreement. My aim will be to consider the debate about the purely scientific merit of the HGP, to sketch the nature of the short-term issues which the project raises, and, finally, to identify what I take to be the deepest and most difficult questions.

The official goals of the HGP are to map and sequence the human genome, and the genomes of other organisms (so-called “model organisms”).

This paper deals with the mutual relation of speculative considerations, experimental activity, and the attempt to establish “laws of nature.” I shall not give a general analysis, but instead study a historical example. It is taken from the work of Michael Faraday - one of the most original and most successful experimenters.

I shall start by giving a rough sketch of Faraday's view, thereby making clear the particular question on which my paper concentrates. In part three, I analyze an episode of Faraday's actual work, and conclude in part four with a rough analysis of the type of explanation given by Faraday.

Faraday repeatedly emphasizes the necessity of distinguishing “that knowledge which consists of assumption, by which I mean theory and hypothesis, from that which is the knowledge of facts and laws; never raising the former to the dignity or authority of the latter, nor confusing the latter more than is inevitable with the former.”

Newborn screening for the genetic disease phenylketonuria (PKU) is generally considered the greatest success story of applied human genetics. Paradoxically, it is invoked both by those who stress the value and those who emphasize the limitations of genetic medicine.

PKU screening is often cited as a model for genetic medicine and as a precedent for those who favor the expansion of genetic tests (Azen 1991, 35; Scriver 1991; Bishop and Waldholz 1990, 18-19). But even those skeptical of most screening programs tend to describe this program in sunny terms (Natowicz and Alper 1991, 387-89; Nelkin and Tancredi 1989, 160). The near-consensus on the success of PKU screening is explained by the variety of interests the example serves. Untreated phenylketonuria results in severe mental retardation and behavioral disorders. But if it is identified in the newborn, the disease is treatable through a special diet.

The purpose of this paper is to provide a systematic account of the role of anomaly in theory change in science. We adopt a naturalist approach to the philosophy of science (e.g., Giere 1985; Maffie 1990) and support our proposal with evidence from the history of science and from the psychology of science.

Previous discussions of the topic of anomaly in theory change have rarely used evidence from psychology. Probably this has been due to the relatively immature state of research in the psychology of science (cf. Gorman forthcoming; Gholson, Shadish, Neimeyer, and Houts 1989). However there is now enough research on the topic of belief change (cf. Chinn and Brewer 1993b) to provide a foundation for theory development in the area of responses to anomaly. Much of the research in this area uses data from undergraduates and children and not scientists (see Dunbar forthcoming, for an exception).

Popper's philosophy is founded on his early conceptions of the problem of demarcation, of its solution, and of the roles of epistemology and methodology. I shall give an account of these, and of his idea of the alternative, ‘naturalistic’ conceptions. I then hope to show that Popper's conceptions are confused.

At the beginning of The Logic of Scientific Discovery Popper tells us that “the task of the logic of scientific discovery, or the logic of knowledge, [is]… to analyse the method of the empirical sciences” (Popper 1959, 27), and that its first job is “to put forward a concept of empirical science, in order to make linguistic usage, now somewhat uncertain, as definite as possible, and in order to draw a clear line of demarcation between science and metaphysical ideas” (1959, 38-39).

In the Museum of Science and Technology in San Jose, California, there is a display dedicated to advances in biotechnology. Most prominent in the display is a double helix of telephone books stacked in two staggered spirals from the floor to the ceiling twenty five feet above. The books are said to present the current state of our knowledge or the eurcaryotic genome: the primary sequences of DNA polynucleotides for the gene products which have been discovered so far in the twenty years since cloning and sequencing the genome became possible.

In order to grasp what is problematical about the human genome project (HGP), I want you to hold on to this image of a stack of phone books, or rather two stacks, helictical in shape. Imagine that each of the phone books about the size of the Manhattan white pages, and that the two stacks of phone books reach up a mile and a half into the sky.

Much of the history of science is missing much of the time. The missing history I have in mind is not missing because of lost documents or state secrecy. Nor is it missing because it is obscure. I am talking about central episodes in the history of science and absolutely central issues in the logical structure and evidential support of those episodes. In fact, the episodes are so central and well known, and the missing history (once seen) so obvious, that one feels compelled to hold that there must be a widespread systematic bias among historians and philosophers against seeing certain explanatory patterns.

My explanation for this missing history of science is that there is a strong tendency among historians and philosophers of science toward what I will call “Psychological Predictivism” to distinguish it from “Logical Predictivism.” Logical Predictivism is the position that, if an observed phenomenon provides good evidence for a hypothesis, then that hypothesis (plus unproblematic auxiliary hypotheses), predicts the phenomenon.

Traditionally, philosophy of science has focused on the product of science: the scientific hypothesis, principle, law, or more grandiosely, the theory. Using logician's license I'll think of hypotheses and theories as ‘little’ and ‘big’ (or ‘weak’ and ‘strong’) propositions. The tradition spoke of the product as (scientific) knowledge; the more recent phrase “current scientific opinion” carries the same connotation of uniqueness. For this to make sense, something is required: a proposition must be capable of being true or false, capable of being fully believed or disbelieved (and if you like, known).

Probabilism requires us to look at every aspect of science in a new way. In his radical brand of probabilism, Richard Jeffrey told us to reconceptualize knowledge as 'probable knowledge’ and propositions as ‘probasitions’—and never to resolve doubt but simply to quantify it, keeping all possibilities in play.

In the course of his forceful (1981) attack on “convergent realism”, Larry Laudan attempted to turn an influential pro-realist consideration on its head. Scientific realists have wondered how a theory could enjoy the sort of empirical predictive success exhibited by presently accepted theories in the “mature” sciences, and yet be radically wrong in what it claims is going on “behind” the empirical phenomena. If nothing like the electrons and other particles postulated by current physics exists, how can the theories that there are such things have made the great range of successful predictions that they do about phenomena observed in particle accelerators and the like? Laudan directs such realists to the history of science and to a list of “once successful” theories which are “(by present lights) non-referring”—a list of successful theories which gave a “central” role to notions that, according to theories we accept now, do not exist (1981, 26).

Richard Jeffrey advocates fallibilism in the form of radical probabilism. Degrees of belief are the objects of prime interest to epistemology and it is rarely plausible that they should take the extreme form of certainty. In particular the creation of certainties by the process of belief change by conditionalization is not necessary:

One of the main goals of no-collapse interpretations of quantum mechanics is to show how results of measurements are objectified, or, in a more poignant terminology, how in a measurement situation facts arise. One needs to show how in their dynamical evolution the measured system and, perhaps more importantly, the measuring apparatus acquire, or at least appear to acquire, the definite properties that are otherwise explained by the collapse of the state. This can be seen as a special case of the problem whether quantum mechanics alone can account for the classical behaviour of macroscopic systems; in particular, the permanent definiteness of at least those properties of macroscopic systems that are directly observable, such as the position of the pointer of a measuring apparatus. In other words, whether quantum mechanics can account for macrofacts of the familiar kind.

Pluralism is usually opposed to realism. That's why realists tend to affirm reductionism, even if only the lapsed reductionism of supervenience. It is no accident that postmoderns talk about the different worlds we live in. The realist is bent upon one world with one history, and that is the history for the sciences to tell about it, albeit with different degrees of precision, for different purposes and different points of view. The opposition between realism and pluralism is multiplied when the domains of different theories float about as in the balloon image of the relation of the sciences (Figure 1) and when no combination of fields can together supply a set of descriptions in terms of which at least one baseline history can be told. But the opposition is not necessary.

In both philosophical writing on science and scientific practice itself there has been a long standing interest in theories and explanatory frameworks that unify various phenomena. In the history of physics the most successful theories are often those that supposedly show how diverse effects can be understood as aspects of a single underlying principle or cause. For example, Maxwell's electrodynamics unified electromagnetism and optics by providing a theoretical demonstration that light and electromagnetic waves have the same velocity and are manifestations of the same kind of process. More recently in the 1970's Glashow, Weinberg and Salam produced a unified description of both electromagnetic and the weak interactions. This electroweak theory successfully describes electromagnetic interactions as well as data from a variety of electroweak processes including scattering and number of different particle collisions.

The decoherence approach to the measurement problem invokes dissipative interactions between a measuring apparatus and its environment to explain, within the context of ‘pure’ quantum mechanics (QM), why such devices appear to possess definite pointer readings. By ‘pure’ QM, I mean Schrödinger evolution with no wavefunction collapse. Several classes of interpretations of pure QM can rely on decoherence. One class is the ‘modal’ interpretations of van Fraassen (1979), Dieks (1989), Healey (1989), and others. Another class is the relative-state and many-world interpretations.

I will argue that decoherence cannot help these interpretations address the general metaphysical challenges raised against them. But decoherence can help pick out a ‘special’ basis that determines which observables receive definite values. I'll explore to what extent decoherence rescues the modal (biorthogonal) basis-selection rule, and Zurek's (environmental interaction) basis-selection rule, from the basis degeneracy problem and the imperfect measurement problem.

Consider the general form of the state of a quantum system, (eq. 1), where the are (non-degenerate) eigenvectors of an operator, A, corresponding to an observable, A. According to the standard interpretation of quantum mechanics (the precise details of which do not concern me here), A does not have a definite value on the system in the state . But now suppose we measure A by coupling the system to a measuring apparatus. The composite system is then (eq. 2) where the are the indicator-states of the apparatus. Again, the standard interpretation tells us that the apparatus is not in a definite indicator-state. But how can this be? Measurements do have definite results. The apparatus is always in a definite state.

I have just reviewed one version of the measurement problem. The modal interpretation of quantum mechanics proposes a solution.

Most discussion of the unity of science has concerned what might be called vertical relations between theories: the reducibility of biology to chemistry, or chemistry to physics, and so on. In this paper I shall be concerned rather with horizontal relations, that is to say, with theories of different kinds that deal with objects at the same structural level. Whereas the former, vertical, conception of unity through reduction has come under a good deal of criticism recently (see, e.g., Dupré 1993), horizontal unity has generally been conceded to be an important goal. The most pressing questions about horizontal unification arise in the study of human behavior. Numerous sciences including psychology, economics, anthropology, sociology, and parts of biology, attempt to provide explanations of human behavior. It is possible that some of these sciences may be able to coexist peacefully or even cooperatively.

It is clear that many philosophers of science are inclined to be sceptical about the scientific ambitions of economics. Sometimes this scepticism amounts to a forthright denial of economists’ entitlement to be granted the epistemic authority normally claimed by scientists (for example, Dupré 1993). A more modest ambivalence may be signalled by a philosopher's refusal to treat the intuitions of economists as data for the philosophy of science, in the way that (e.g.) physicists’ ontological and epistemological judgements are now routinely treated. The following paper is part of a much larger project that criticizes the basis for this scepticism, at least where microeconomics is concerned. This general project is partly motivated by our belief that philosophers have often viewed microeconomics from a highly distorting set of perspectives. One source of these distortions is a sociological accident: the philosophy of economics, as a part of the philosophy of science, has been largely owned since its outset by Popperians and their intellectual descendants.

The discipline of biological taxonomy is rife with philosophical controversies. One of them is particularly relevant to the topic of this symposium, namely the question of taxonomic unity. Should biologists aim for a single correct classification of the world's organisms or should they allow a plurality of equally correct classifications?

For those with little or no background in evolutionary biology, the suggestion of taxonomic pluralism might seem odd. Don't introductory biology texts as well as television nature shows suggest that there is a single correct way to sort the world's organisms? They do, but that advertised agreement masks a number of controversies that have raged in biology since Darwin's time. Consider the question of how to sort organisms into species. Currently there are no less than seven prominent definitions of the species category (Ereshefsky 1992a).