The claim that theoretical entities are not real, that they are merely convenient fictions, has been defended and attacked in diverse ways. This paper is concerned with only one defense of the fictionalist thesis and with a certain realist attack on it. The defense in question is that theories which prima facie make reference to theoretical entities can be revised in such a way that no such apparent reference is made by eliminating all occurrences of theoretical expressions. It will be argued here that there is a procedure for revising theories which meets certain minimal criteria of adequacy, contrary to arguments in the literature. Further, it will be argued that the existence of this procedure provides neither sufficient nor necessary support for the fictionalist thesis, that this procedure is not of significance in the dispute between the fictionalist and the realist. Whether or not the theoretical-nontheoretical distinction is viable is another story which will not be told here. It will be assumed for the sake of argument that such a distinction can be drawn.

Biological foundations of the psychoneural identity hypothesis are explicated and their implications discussed. “Consciousness per se” and phenomenal contents of consciousness per se are seen to be identical with events in the (unobserved) brain in accordance with Leibniz's Law, but only informationally equivalent to neural events as observed. Phenomenal content potentially is recoverable by empirical means from observed neural events, but the converse is not possible. Consciousness per se is identical with events which do not represent anything distal to sensory receptor-transducer systems. Thus, on the psychoneural identity hypothesis, consciousness per se comprises directly physical events-in-themselves rather than being a Euclidean representation of physical events as is the case for phenomenal content. After comparing consciousness per se to “onta,” a paradox is suggested: rather than being irreducible to physical reality, consciousness per se is the only experience congruent with the ultimate nature of physical reality as conceived by contemporary physics.

Projectible conditions are (roughly) those whose universal generalizations are con firmed by their positive instances. This paper proposes certain modifications to the above definition in order to capture the pre-analytic notion it is supposed to explicate. Then we investigate what logical operations, when performed on projectible conditionals, yield new projectible conditionals. A number of surprising theorems are proven, and these theorems indicate that few conditionals having complex antecedents and consequents are projectible. It is also shown that projectibility is not closed under contraposition, and this is proposed as a solution to the Paradox of the Ravens. Finally, a general conjecture is made concerning just what conditionals are projectible, and it follows from this conjecture that although most conditionals are not projectible, they can still be dealt with inductively, but in ways more complex than recognized by classical confirmation theory.

What has been learned about logic by means of “uninterpreted” logistic systems can be supplemented by comparing the latter with systems which are more uninterpreted, as well as with others which are less uninterpreted than the well-known logistic systems. By somewhat extending the meaning of ‘uninterpreted’, I hope to establish certain claims about the nature of logistic systems and also to cast some light on the nature of “logic itself.”

My procedure involves looking at three major “degrees” of interpretation: first, systems uninterpreted both semantically and syntactically, second, systems uninterpreted semantically but not syntactically, and third, systems uninterpreted neither semantically nor syntactically. We shall be forced to limit ourselves to the truth-functional part of logic in this brief study. What are usually called uninterpreted systems can be seen on a continuum of “degrees” of interpretation, from ordinary reasoning at one extreme to a “thoroughly uninterpreted system” at the other.

“Logic itself” apparently lies nearer to the interpreted, deformalized end of the spectrum than to the uninterpreted, formalized end. Logic is not identical with any particular logistic system, but is that which the particular logistic systems aim to formalize or model or capture. I propose that it is that minimum set of logical, rather than syntactical, primitive terms, definitions, and rules which is needed to generate logically, rather than syntactically, the principles of ordinary reasoning as it is used by logicians in their metalinguistic discussions and informal proofs of metatheorems. This minimum set is somewhat larger than the primitive bases of most logistic systems; its truth-functional part is presented in the “Deformalized Logic” at degree twelve.

Numerous criticisms of Adolf Grünbaum's account of conventions in physics have been published ([1], [2], [3], [4], [13]), and he has replied to most of them ([6], [8]). Nonetheless, there seem to me to be good reasons for offering further criticism. In the first place Grünbaum's philosophy seems to me at least partly an extrapolation of one aspect of the views on conventions developed by Reichenbach and others. Since I think many of the issues which Reichenbach attempted to settle in his various discussions of conventions in physics are genuine and important, and I also think that those aspects of his views on which Grünbaum has focused are among the least satisfactory, it seems important to suggest questions and answers about conventions in physics which may develop more satisfactory Reichenbachian themes. Secondly, Grünbaum's philosophy centers on a distinction, that between extrinsic and intrinsic properties and relations, which has never been made satisfactorily clear either by Grünbaum or by his critics. Until it is clarified we will remain unsure of just what he is claiming and why we should think it true or think it false. Finally, Grünbaum's replies to his critics, especially his most recent reply, [9], involve unusually important claims which fail to be buttressed by the arguments he gives. I have in mind such claims as that we can learn something important about the ontological status of properties and relations by examining descriptions of them, that on (what I take to be) the most straightforward and literal interpretation, the general theory of relativity is inconsistent, and that the foremost advocates of geometrodynamics, Clifford and Wheeler, were and are enmeshed in contradiction. My own view is that all of these claims are dubious or false, but I shall be less concerned with establishing their falsity than with discrediting the arguments offered for them.

In recent years there has been considerable discussion and controversy concerning the concepts of mental health and mental illness. The controversy has centered around the problem of providing criteria for an adequate conception of mental health and illness, as well as difficulties in specifying a clear and workable system for the classification, understanding, and treatment of psychological and emotional disorders. In this paper I shall examine a cluster of these complex and important issues, focusing on attempts to define ‘mental health’ and ‘mental illness’; diverse factors influencing the ascription of the predicates ‘is mentally ill’ and ‘is mentally healthy’; and some specific problems concerning these concepts as they appear in various theories of psychopathology. The approach here will be in the nature of a survey, directed at the specification of a number of problems—conceptual, methodological, and pragmatic—as they arise in various attempts to define and to provide criteria for applying the concepts of mental health and mental illness.

In Chapter 4 of Science and Subjectivity, I offered several arguments critical of Professor Thomas Kuhn's views as expressed in his influential book The Structure of Scientific Revolutions. His recent replies to these criticisms seem to me so inadequate as to suggest that he, and therefore others as well, may have failed to grasp their full import. Accordingly, I shall, in the first part of this paper, briefly recapitulate my earlier arguments and offer a short rejoinder to Professor Kuhn's replies. The second part of the paper will expand upon my earlier discussion to consider the basic metaphors of vision and revolution, offered by Kuhn to replace the traditional notion of deliberation. My argument here will be that these new metaphors are incongruous in critical respects, and my discussion will conclude by considering their relations to the contrast between understanding and accepting a theory.

In a recent paper [2] David Lewis offered an extremely interesting and, if correct, important solution to the main unsolved problem of Carnap's program for inductive logic—the choice of an appropriate C-function (=an inductive method). The gist of Lewis' solution is to first obtain a pilot sample from the target population (a time-honored procedure in statistical methodology) and then select, on the basis of this sample, from among the immodestλ-methods. An immodest inductive method is one which estimates that the mean squared error of its estimates of population relative frequencies is less than or equal that of any other inductive method. By great ingenuity Lewis apparently shows that on any evidence e there is one and only one immodest λ-method. I will attempt to show that Lewis made a conceptual error in formulating the equations to be solved and that when it is corrected it can be easily demonstrated that all admissible λ-methods are immodest and hence that Lewis' criterion is of no value.

Machines and Biology have been, since antiquity, closely related. From the zoological figures present in astronomical simulacra, through renaissance mechanical imitations of animals, through Decartes' wind pipe nerves, to present day discussions on the computer and the brain, runs a continuous thread. In fact, the very name of mechanism for an attitude of inquiry throughout the history of Biology reveals this at a philosophical level ([4] and [6]). More often than not, mechanism is mentioned in opposition to vitalism, as an assertion of the validity of the objectivity principle in biology: there are no purposes in animal nature; its apparent purposefulness is similar to the purposefulness of machines. Yet, the fact that one picks machines as a set of objects comparable to living systems, deserves a closer look. What in machines makes it possible to establish such a connection?

In a recent article in Philosophy of Science Janet Travis [13] seeks to refute the argument for evolutionary progressivism which is based on a series of dominant life forms on the grounds that there is no rigorous definition of that concept. In particular she claims that the definitions formulated by Sir Julian Huxley and George Gaylord Simpson fail adequately to exclude any group of organisms. The concept of dominance is therefore alleged to be meaningless and the argument for progress invalid.

Direct Realism as a theory of perception has traditionally been thought to collapse on the existence of hallucinations. The cause of that collapse is what is familiar to philosophers as the Argument from Illusion. And what sustains that argument is the equally familiar No-Intrinsic-Difference Claim. The argument and the claim conspire to undermine Direct Realism as follows. We are first given cases in which we are acquainted with perceptual states of affairs that can be neither material bodies nor parts of such bodies. We are told that what we see in such cases is phenomenally indistinguishable from what we see in cases of veridical perception: There is, so the argument goes, no characteristic of either kind of state of affairs available to inspection which enables us to distinguish one from the other. And since there is no phenomenal difference between them, there is also no intrinsic difference; hence, we are never directly aware of material bodies or their parts in perception—from which it is generally inferred that Direct Realism is false.

Stegmüller's most recent publication, Theorie und Erfahrung, is the second of four volumes of a work which appears under the general title Probleme und Resultate der Wissenschaftstheorie und analytische Philosophie, ([36], all references in the discussion below are taken from the second volume of this work). In this voluminous and daring work the author intends to deliver a systematic, critical account of the most important literature which has appeared on various basic topics of philosophy of science and its underlying assumptions over the past twenty-five years. The work promises to become a classic in the German language because of its comprehensiveness, thoroughness, and clarity.