This paper defends a counterfactual account of explanation, according to which successful explanation requires tracing patterns of counterfactual dependence of a special sort, involving what I call active counterfactuals. Explanations having this feature must appeal to generalizations that are invariant—stable under certain sorts of changes. These ideas are illustrated by examples drawn from physics and econometrics.

Recently a number of authors have tried to avoid the failures of traditional Dutch book arguments by separating them from pragmatic concerns of avoiding a sure loss. In this paper I examine defenses of this kind by Howson and Urbach, Hellman, and Christensen. I construct rigorous explications of their arguments and show that they are not cogent. I advocate abandoning Dutch book arguments in favor of a representation theorem.

In this paper I criticize Cartwright's analysis of capacities and offer an alternative analysis. I argue that Cartwright's attempt to connect capacities to her condition CC fails because individuals can exercise capacities only in certain contexts. My own analysis emphasizes three features of capacities: 1) Capacities belong to individuals; 2) Capacities are typically not metaphysically fundamental properties of individuals, but can be explained by referring to structural properties of individuals; and 3) Laws are best understood as ascriptions of capacities.

The Bell 1964 theorem states that nonlocality is a necessary feature of hidden variable theories that reproduce the statistical predictions of quantum mechanics. In view of the no-go theorems for non-contextual hidden variable theories already existing up to 1964, and due to Gleason and Bell, one is forced to acknowledge the contextual character of the hidden variable theory which the Bell 1964 theorem refers to. Both the mathematical and the physical justifications of this contextualism are reconsidered. Consequently, the role of contextualism in recent no-hidden-variables proofs and the import of these proofs are investigated. With reference to the physical intuition underlying contextualism, the possibility is considered whether a context-dependence of individual measurement results is compatible with context-independence of the statistics of measurement results.

In this paper I take issue with the doctrine that organisms belong of their very essence to the natural kinds (or biological taxa, if these are not kinds) to which they belong. This view holds that any human essentially belongs to the species Homo sapiens, any feline essentially belongs to the cat family, and so on. I survey the various competing views in biological systematics. These offer different explanations for what it is that makes a member of one species, family, etc. a member of that taxon. Unfortunately, none of them offers an explanation that is compatible with the essentialism in question.

In this paper I will examine the history of the first three, of a sequence of five, experiments performed by the Mann-O'Neill collaboration at the Princeton-Pennsylvania Accelerator. The experiments were conducted over a period of four years and measured aspects of K+ meson decay. Each of the experiments was done with essentially the same basic apparatus, with modifications for each of the specific measurements. We will see the increasing expertise of the experimenters as the experiments progressed. The third measurement was technically more difficult and built upon the acquired knowledge of how the experimental apparatus worked.

In this paper, I respond to some criticisms of Greenwood (1996) advanced by Grünbaum (1996) and Erwin (1996). I argue that Grünbaum's problematic account of “placebo effects” and placebo control treatments does not really address, far less resolve, the problems with experimental evaluations of psychotherapy documented in my original paper.

Philosophers disagree how abstract, theoretical principles can be applied to instances. This paper generates a puzzle for law theorists, causal theorists and inductivists alike. Intractability can force scientists to use a “semi-empirical” method, in which some of an equation's theoretically-determinable parameters are replaced with values taken directly from the data. This is not a purely deductive or inductive process, nor does it involve causes and capacities in any simple way (Humphreys 1995). I argue the predictive successes of such methods require us to reanalyze our views about the nature of prediction, the status of models, and the goal(s) of science. When laws and experimental evidence are neither individually nor jointly sufficient for prediction, models become the locus of understanding. I analyze an historically important debate about the use of semi-empirical methods to construct potential energy surfaces.

1. Introduction. The papers by Hellman and Mayo offer up a rich menu of problems and proposed solutions, so there is much here for a friendly critic to fasten on. In order to bring a modicum of focus to my commentary, I shall limit my remarks to the Duhem problem and its radiations in epistemology and methodology. Both Mayo and Hellman claim to have solutions to that hoary old problem and they tout these solutions as key indicators of the explanatory power of their respective technical epistemologies, whether Bayesian or Neyman/Pearsonian. Like Mayo, I shall be arguing that the Bayesian treatment of Duhem's problem is no solution at all; that, indeed, it fails to grapple with the core challenges posed by the purported ambiguities of falsification. My response to Mayo's more detailed, and I think more right-headed, treatment of the Duhem problem will be more complex. While I believe that she is moving in the right direction in many respects, I think that she fails to see one key dimension of the Duhemian conundrum. Indeed, she risks solving not Duhem's problem but quite a different one. I shall gently try to encourage her to steer her way back towards the central task.

1. Introduction. Attempts to utilize the probability calculus to prove or disprove various inductive or inductive skeptical theses are, I believe, highly problematic. Inductivism and inductive skepticism are substantive (logically consistent) philosophical positions that do not allow of merely formal proofs or disproofs. Often the problems with particular alleged formal proofs of inductive or inductive sceptical theses turn on subtle technical considerations. In the following I highlight such considerations in pointing out the flaws of two proofs, one an alleged proof of an inductive sceptical conclusion due to Karl Popper, the other an alleged proof of an inductivist thesis originally due to Harold Jeffreys and later advocated by John Earman. Surprisingly, in examining Popper's argument it is shown that certain apparently weak premises, often embraced by both inductivists and deductivists, lend themselves to inductive conclusions. However it is argued that those premises are still philosophically substantive and not amenable to a purely formal demonstration. The lesson to be learnt here is twofold. First, we need to be very careful in determining which formal theses entail, and which are entailed by, inductive skepticism and inductivism. Second, we need to take great care in laying out and examining the assumptions presumed in formal arguments directed for and against such formal theses. In a follow up article I will consider various attempts by David Stove and Karl Popper and David Miller to identify the exact content of inductive skepticism and propose a new identification based on the theory of content developed in Gemes 1994. Finally I will compare this new version with that proposed recently in Alberto Mura 1990.

Frances Egan argues that the states of computational theories of vision are individuated individualistically and, as far as the theory is concerned, are not intentional. Her argument depends on equating the goals and explanatory strategies of computational psychology with those of its algorithmic level. However, closer inspection of computational psychology reveals that the computational level plays an essential role in explaining visual processes and that explanations at this level are nonindividualistic and intentional. In conclusion, I sketch an account of content in which content does the sort of explanatory work that Egan denies is possible.

I show that van Fraassen's empiricism leads to mutually incompatible claims with regard to empirical theories. He is committed to the claim that reasons for accepting a theory and believing it are always identical, insofar as the theory in question is an empirical theory. He also makes a general claim that reasons for accepting a theory are not always reasons for believing it irrespective of whether the theory is an empirical theory.

This paper discusses a series of case studies on observations, experiments, and the theoretical interpretation between 1890 and 1960 of a shift of dark Fraunhofer lines in the solar spectrum. I argue for the use of flow charts to analyze interconnections and to identify sequences of research strategies. Also I advocate using a newly-developed tool called “block diagram” representation of experimental systems as an appropriate method to identify recurrent patterns in the interplay of instrumentation, experiment, and theory in research episodes.

Treating species as individuals and not classes has been crucial to the integration of evolutionary theory with modern systematics. Despite the theoretically important role the concept of individuality plays in modern phylogenetic systematics and in evolutionary theory more generally, many have been content to rely on common-sense intuitions about what counts as an individual. One of the most often cited intuitions is that individuals should be defined intrinsically. Unfortunately, common-sense intuitions like this one have proven to be inadequate for identifying and characterizing historical individuals (like species). An examination of real-world biological examples shows that our common-sense intuitions are equally inadequate when applied to at least some biological organisms—the paradigm individuals.

Starting with some illustrative examples, I develop a systematic account of a specific type of experimentation—an experimentation which is not, as in the “standard view”, driven by specific theories. It is typically practiced in periods in which no theory or—even more fundamentally—no conceptual framework is readily available. I call it exploratory experimentation and I explicate its systematic guidelines. From the historical examples I argue furthermore that exploratory experimentation may have an immense, but hitherto widely neglected, epistemic significance.

A recent article (Leeds and Healey 1996) argues that the modal interpretation (Copenhagen variant) of quantum mechanics does not do justice to immediately repeated non-disturbing measurements. This objection has been raised before, but the article presents it in a new, detailed, precise form. I show that the objection is mistaken.

Robert Wilson (1994) maintains that many interesting and fundamental aspects of psychology are non-individualistic because large chunks of psychology depend upon organisms being deeply embedded in some environment. I disagree and present one version of narrow content that allows enough reference to the environment to meet any wide challenge. I argue that most psychologists are already this sort of narrow content theorist and that these narrow content explanations of psychological phenomena meet Wilson's criteria for being a good explanation better than any wide explanation of the same event.