In studies of scientific methodology, surprisingly little attention has been given to tests of hypotheses. Such testing constitutes a methodology common to various scientific disciplines and is an essential factor in the development of science since it determines which theories are retained. The classical theory of tests is a major accomplishment but requires modification in order to produce a theory that accounts for the success of science. The revised theory is an analysis of the nondeductive aspect of scientific reasoning. It results in a new definition of probability and a nonclassical point of view with regard to the foundations of probability.

It is shown that quantum mechanics cannot be formulated as a stochastic theory involving a probability distribution function of position and momentum. This is done by showing that the most general distribution function which yields the proper quantum mechanical marginal distributions cannot consistently be used to predict the expectations of observables if phase space integration is used. Implications relating to the possibility of establishing a “hidden” variable theory of quantum mechanics are discussed.

It is shown how a causal ordering can be defined in a complete structure, and how it is equivalent to identifying the mechanisms of a system. Several techniques are shown that may be useful in actually accomplishing such identification. Finally, it is shown how this explication of causal ordering can be used to analyse causal counterfactual conditionals. First the counterfactual proposition at issue is articulated through the device of a belief-contravening supposition. Then the causal ordering is used to provide modal categories for the factual propositions, and the logical contradiction in the system is resolved by ordering the factual propositions according to these causal categories.

A proof is given that there does not exist an event, that is not already in the past for some possible distant observer at the (our) moment that the latter is “now” for us. Such event is as “legally” past for that distant observer as is the moment five minutes ago on the sun for us (irrespective of the circumstance that the light of the sun cannot reach us in a period of five minutes). Only an extreme positivism: “that which cannot yet be observed does not yet exist”, can possibly withstand the conclusion concerned. Therefore, there is determinism, also in micro-physics.

The paper∗∗ discusses the problems raised by the inexactness of experiential concepts for a deductivist account of theoretical explanation. The process of theoretical explanation is explicated in terms of the devising of exact forms of inexact concepts. Analysis of the adjustments of concepts and their exact forms to each other reveals an implicit criterion of adequacy for theories which is related to the principle of connectivity.

I Physicalism, and the weak identity theory deny, while physicalism2 and the radical identity theory assert, that raw feels can be accomodated in a purely physicalistic framework.

II A way of interpreting the claim of physicalism1 is that raw feels are emergents.

III The doctrine of emergence asserts that: (i) there are different levels of existence, (ii) these levels of existence are distinguishable on the basis of the behaviour of entities of that level, and (iii) an adequate scientific explanation of a lower level is inadequate for a higher level.

IV The criteria of emergence are novelty and a priori unpredictability.

V Either qualities or laws or both may be regarded as emergents.

VI If the alleged impossibility of explaining higher level phenomena on the basis of explanation adequate for lower level phenomena is logical, then the impossibility is either trivial or it implies indeterminism.

Consideration of theories of emergence:

• VII Semantic emergence. On this view emergence is theory-bound, analogous to indefinability or indemonstrability.

• VIII Methodological emergence. On this view what we regard as emergents depends on the theory we construct.

• IX Nomological emergence. On this view emergence is an empirical problem.

Conclusion: if there are emergents, physicalism2 and the radical identity theory probably have to be abandoned. However, unless actual examples of emergents are produced both theories hold. The logical possibility of falsification is not an objection against physicalism2 and the radical identity theory; it is one of their merits.

A working theory can involve a compromise between pragmatic application and pure theory. This is illustrated by the development of Coombs's theory of data. The original version of the theory purported to guide investigators in the use of scaling techniques, but subsequent revisions including a logico-mathematical statement of the theory do not show whether the practical recommendations made earlier still apply. These practical recommendations, some of which Coombs has discarded to obtain a comprehensive theory, are important in spite of shortcomings as they reveal differences between attitude and mental test data. The different forms of Coombs's theory point to the existence of a general problem, how to find a compromise between practice and pure theory.

Central to Paul K. Feyerabend's philosophy of science are two theses: (1) there is no standard observation language available to science; instead, observability is to be viewed as a pragmatic matter; and (2) when considering questions of empirical significance and experimental test, the methodological unit of science is a set of inconsistent theories. I argue that the pragmatic theory of observation by itself decides neither for nor against any particular specification of meaning for an observation language; and that Feyerabend's position provides no decision procedure when two contending theories share no terms having the same meaning, and thus cannot be said to be logically incompatible. Also, Feyerabend's insistence upon falsification will force him to admit that there are relatively permanent facts available to all theories, or to abandon the idea of test as falsification and to conclude that scientific theories can only be accepted or rejected on the basis of non-evidential considerations.