The problem of the critical assessment of theories across paradigms raised by Kuhn is not resolved, it is argued, either by Scheffler's appeal to initial credibility or by Lakatos' conception of a research program. It is argued further that, in these contexts, the notion of reasonable choice by individuals makes no sense. The conclusion supports Feyerabend's position of “epistemological anarchism.”

This paper defends a realist interpretation of theories and a modest realism concerning the existence of quantities as providing the best account both of the logic of quantity concepts and of scientific measurement practices. Various operationist analyses of measurement are shown to be inadequate accounts of measurement practices used by scientists. We argue, furthermore, that appeals to implicit definitions to provide meaning for theoretical terms over and above operational definitions fail because implicit definitions cannot generate the requisite descriptive content. The special case of establishing a temperature scale is examined to show that nonrealist accounts fail to provide insight into the theoretical connections that scientific laws postulate to hold among quantities.

Some scientists believe that although evolutionary theory is explanatory, it does not have, in contrast to the theories of physics, any predictive power. This raises the question of its testability. The analysis given shows that there are good reasons to claim the unpredictability of evolutionary events; nevertheless, the evolutionary theory has potential predictive power. It is argued that the difference between biology and physics lies not in the predictive power of the theories involved, but in the different weight which is lent to the forecasting of particular events in these sciences. A second source of confusion derives from the ambiguity of the term ‘prediction’. In order to define ‘prediction’ for cases in which the term is used to refer to a part of testing procedure, the reference to the time-point “now” is quite irrelevant. Prediction of unknown observational data is sufficient for testing a hypothesis, but such prediction may or may not be identical with forecasting of future events. Different factors that may cause particular difficulties met by biologists in forecasting future events are analyzed subsequently in the second part of the paper. The conclusion is drawn that although particular cognitive situations limiting the ability of forecasting are very frequent in biological sciences, the claim about the peculiar logical status of biological theories is not thereby justified.

A philosophical interpretation of quantum mechanics presupposes a clear understanding of what is asserted by this theory. The aim of this paper is to help clarify one specific theorem of quantum mechanics, namely the so-called uncertainty relations. The surprisingly wide spread belief that these relations generally imply a reciprocal or inversely proportional relationship between the respective uncertainties is shown to be mistaken. Several reasons why this mistaken belief has been embraced are suggested. The conditions under which one could say that the uncertainty relations imply an inversely proportional relationship between uncertainties are specified.

Subjunctive conditionals have their uses, but constituting the meaning of dispositional predicates is not one of them. More germane is the analysis of dispositions in terms of “bases”—except that past efforts to maintain an ontic gap between dispositions and their bases, while not wholly misguided, have failed to appreciate the semantic birthright of dispositional concepts as a species of theoretical construct in primitive science.

To overcome sociopsychologism and historical relativism, the growth of science is deduced from the combined effect of postulated invariant controls, in the form of enduring ideals of science, in their interaction with nature. The thus constituted “cybernetics-of-science” concept permits extrapolation from present to future states of science. The ideal scientific theory is the goal or target toward which the scientific process is oriented, by virtue of its invariant controls. The form of the ideal theory can thus be extrapolated, and some speculative hypotheses advanced as to its contents, taking those of the recently emerged constructs of science as basis which best accord with the predicted form of the theory.