Two types of philosophical arguments are employed by the defenders and critics of the Copenhagen Interpretation. One type of argument is a confrontation of an opponent's interpretation with criteria of demarcation and criteria of acceptability. The purpose of such arguments is either to exclude an opponent's interpretation from the range of permissible discourse in quantum physics, or to establish the inadequacy of an opponent's interpretation. A second type of argument is a justification of the value, or utility, of the criteria selected.

To illustrate one way in which philosophy may be helpful rather than merely critical in the present state of psychoanalytic theorizing, an attempt is made to disentangle issues in controversies about the unconscious. Eleven questions are distinguished and discussed. Logical, linguistic, methodological, metaphysical, empirical, and pragmatic components are set apart. It is found that there are no logical barriers to a construct of the unconscious, that it is linguistically feasible, need violate no methodological concepts, nor foreclose a metaphysical issue, nor have deleterious pragmatic effect. Feasibility and desirability of the construct in all these respects will depend on the character and extent of the scientific findings. Some issues are also raised concerning desirable types of models in the explanation of conduct, and concerning the relevance of recent studies of consciousness.

Conditions are stated under which the “argument by analogy” is consistent with the principle of inverse probability. It is contended that the argument by analogy, in conjunction with a crucial test, has a legitimate place in scientific logic. As an example the astrophysical problem of solar granulation is discussed in detail and other examples are mentioned more briefly.

It is shown that a number of questions, usually considered philosophical rather than scientific, can be reformulated to apply to a world of automata or “well-informed heat engines.” In some cases they admit of physical answers, but in many cases obtaining answers entails violation of the second law of thermodynamics. This is demonstrated explicitly for the problem of determinism and free will, for the discovery of the origin or ultimate fate of the universe, or for the discovery of causes or purposes in nature.

Definitions can be classified from (at least) two different points of view. We can ask what sort of statements definitions are, how they are to be justified, and what purpose they serve in the process of acquiring scientific knowledge. For lack of a simpler word, let us call a classification of definitions from this point of view epistemological. We can also distinguish different forms of definition; and a classification from this point of view is naturally called formal.