Does the viability of the discovery program depend on showing either (1) that methods of generating new problem solutions, per se, have special probative weight (the per se thesis); or, (2) that the original conception of an idea is logically continuous with its justification (anti-divorce thesis)? Many writers have identified these as the key issues of the discovery debate. McLaughlin, Pera, and others recently have defended the discovery program by attacking the divorce thesis, while Laudan has attacked the discovery program by rejecting the per se thesis. This disagreement over the central issue has led to communication breakdown. I contend that both friends and foes of discovery mistake the central issues. Recognizing a form of divorce helps rather than hurts the discovery program. However, the per se thesis is not essential to the program (nor is the related debate over novel prediction); hence, the status of the per se thesis is a side issue. With these clarifications in hand, we can proceed to the next stage of the discovery debate–the development (or revival) of a generative conception of justification which goes beyond consequentialism to forge a strong linkage of generation (or rather, generatability) with justification.

The main argument of this paper is that philosophical difficulties regarding scientific discovery arise mainly because philosophers base their arguments on a flawed picture of scientific research. Careful examination of N. R. Hanson's treatment of Kepler's discovery not only puts the rationality of this discovery beyond question, it also reveals what its rationality consists in. We can retrieve the point stressed by Hanson concerning the rational character of discoveries such as Kepler's even as we reject the type of “logical” analysis he proposes.

By a logical theory I mean a formal system together with its semantics, meta-theory, and rules for translating ordinary language into its notation. Logical theories can be used descriptively (for example, to represent particular arguments or to depict the logical form of certain sentences). Here the logician uses the usual methods of empirical science to assess the correctness of his descriptions. However, the most important applications of logical theories are normative, and here, I argue, the epistemology is that of wide reflective equilibrium. The result is that logic not only assesses our inferential practice but also changes it. I tie my discussion to Thagard's views concerning the relationship between psychology and logic, arguing against him that psychology has and should have only a peripheral role in normative (and most descriptive) applications of logic.

The paper attempts to elucidate and evaluate William Whewell's notion of a “consilience of inductions.“ In section I Whewellian consilience is defined and shown to differ considerably from what latter-day writers talk about when they use the term. In section II a primary analysis of consilience is shown to yield two types of consilient processes, one in which one of the lower-level laws undergoes a conceptual change (the case aptly discussed in Butts [1977]), and one in which the explanatory theory undergoes conceptual “stretching.” In section III both consilient cases are compared to the non-consilient case in reference to L. J. Cohen's method of relevant variables. In section IV we examine the test procedures of the theory in all three cases, and it is shown that in the event of genuine consilience (consilience of the second type) a theory acquires extraordinarily high support. In the final section something is said of the shortcomings of standard Bayesian confirmation theories that are highlighted by Whewellian consilience.

In clinical and agricultural trials, there is the danger that an experimental outcome appears to arise from the causal process or treatment one is interested in when, in reality, it was produced by some extraneous variation in the experimental conditions. The remedy prescribed by classical statisticians involves the procedure of randomization, whose effectiveness and appropriateness is criticized. An alternative, Bayesian analysis of experimental design, is shown, on the other hand, to provide a coherent and intuitively satisfactory solution to the problem.

Can there be good reasons for judging one set of probabilistic assertions more reliable than a second? There are many candidates for measuring “goodness“ of probabilistic forecasts. Here, I focus on one such aspirant: calibration. Calibration requires an alignment of announced probabilities and observed relative frequency, e.g., 50 percent of forecasts made with the announced probability of .5 occur, 70 percent of forecasts made with probability .7 occur, etc.

To summarize the conclusions: (i) Surveys designed to display calibration curves, from which a recalibration is to be calculated, are useless without due consideration for the interconnections between questions (forecasts) in the survey. (ii) Subject to feedback, calibration in the long run is otiose. It gives no ground for validating one coherent opinion over another as each coherent forecaster is (almost) sure of his own long-run calibration. (iii) Calibration in the short run is an inducement to hedge forecasts. A calibration score, in the short run, is improper. It gives the forecaster reason to feign violation of total evidence by enticing him to use the more predictable frequencies in a larger finite reference class than that directly relevant.

This paper addresses a recent argument of the Churchlands against the “linguistic-rationalist” tradition exemplified by current cognitive-computational psychology. Because of its commitment to methodological solipsism–the argument goes–computational psychology cannot provide an account of how organisms are able to represent and “hook up to” the world. First I attempt to determine the exact nature of this charge and its relation to the Churchlands' long-standing polemic against ‘folk psychology’ and the linguistic-rationalist methodology. I then turn my attention to the Churchlands' account of what it is for computational psychology to be methodologically solipsistic. I argue that there is no reason to suppose that methodological solipsism commits one to a purely syntactic theory of the mind (of the kind that Stephen Stich has recently advocated): the formality constraints that methodological solipsism imposes on psychological explanation do not exclude ‘essential’ reference to the representational content of mental states, as long as this content is construed in the ‘narrow’ sense. I conclude by raising a problem for computational psychology that may provide some real cause for concern.