Are objects in convex passenger-side mirrors “closer than they appear”? If one adapts to inverting goggles, does the world go back to looking the way it was before, or does the world look approximately the same throughout the course of adaptation, only losing its normative sense of wrongness? The answers to these empirical, introspective questions might help cast light on the classic philosophical debate about the degree of resemblance between our visual experience of reality and things as they are in themselves.

Anyone who has worked in Science for forty years can be much surprised to realize how little he now hears about evolution, compared with such former times. At present, evolution seems to be accepted as an axiomatic or universal principle, while the mechanism of it is not much considered, except by a small group of specialists, who work on the subject in greatly limited ways. This is practically a reversal of the former emphasis. The chemist would probably suggest that the change is due to a better realization of the chemical difficulties involved in the mechanics of evolution, and his own change in viewpoint. The chemical difficulties will have increased to an almost incredible degree in this period, and his viewpoint will have changed correspondingly. A glance at some of these changes should illuminate the progress made in both subjects in this period.

At the outset it will be useful, I think, to distinguish the following components in the definitional situation:

1. The “definitional relation” that holds, in a given case, between either (1) a definiendum and definiens (a dyadic symmetrical relation between symbols) or (2) a definiendum, definiens, and referent (a triadic relation between (a) the symbol being defined, (b) the defining symbol, which is usually complex and includes descriptive terms, and (c) any member of the class of non-symbolic referents by means of references to which the descriptive terms in (b) are given their semantical meaning—the relation between (b) and (c) being non-symmetrical, even though the relata are, in some contests, functionally equivalent. The former syntactical relation connects one symbol (the definiendum) with another symbol (the definiens); the latter semantical relation also does this, but includes the additional factor of a descriptive reference, via the definiens, to a class of non-symbolic referents.

Marc Lange has recently raised three objections to the account of minimal model explanations offered by Robert Batterman and Collin Rice. In this article, I suggest that these objections are misguided. I suggest that the objections raised by Lange stem from a misunderstanding of the what it is that minimal model explanations seek to explain. This misunderstanding, I argue, consists in Lange’s seeing minimal model explanations as relating special types of models to particular target systems rather than seeing minimal model explanations as looking to explain robust patterns of behavior that are exhibited by a variety of physically diverse systems.

According to the Laplacian definition, the probability of an event is the ratio of “favorable” cases to possible cases. It is obvious that the definition presupposes the equal probability of the possible cases; and to make the definition of probability depend upon the conception of equal probability has the appearance, at least, of a vicious circle. Moreover it is hard to see how we can assure ourselves that each possible case is really no more and no less probable than any other. But even if we define probability as the relative frequency of occurrence of events under a given set of conditions, or of true conclusions from premises of a given type, we still require the conception of equal probability, unless indeed we choose to renounce entirely the mathematical expression and calculation of probabilities.

This paper derives a mathematical expression giving the development of the probability of a scientific hypothesis with the number of confirming tests, as determined by Bayes's theorem, in a special case in which all the tests are “independent” of one another. The simple expression obtained shows clearly how the various factors influence the growth of the probability. The result is used to set a numerical lower bound on the probabilities representing the a priori beliefs of humans in generalizations that become accepted. By making a comparison with the predictions of a “logical atomic” model in the case of physical laws, it is argued that humans have significant a priori “knowledge” in a weak sense.

Microphysical realism is the position that the only real entities and properties are found at the most fundamental level of nature. In this article, I challenge microphysical realism concerning properties and natural kinds. One argument for microphysical realism about entities, the “nothing-but argument,” does not apply to properties and kinds. Another argument, the “causal exclusion argument,” cannot be sustained in light of modern physics. Moreover, this argument leads to an objection against microphysical realism, based on the “illusoriness of macroproperties.” Another objection is based on the possibility that there is no fundamental level but a “bottomless pit.”

Comments on Professor Feigl's very comprehensive review of the problem of existential hypotheses may take one of two forms. One may accept the problem in Feigl's own terms and either sympathize or criticize the realistic empiricism to which he subscribes. Or, one may feel that the entire approach is ill-founded, and hence that the distinctions in viewpoints which he draws are comparable to splits in a political party whose basic tenets are incompatible with one's own. This comment takes the second course, and as a commentary can do little more than point out the more serious of the differences which separate Feigl's views from those of the writer.

Recently Albert and Hemmo and Shenker have argued that, contrary to what is sometimes suggested, Liouville's theorem does not prohibit a Maxwellian demon from operating but merely places certain restrictions on its ability to operate. There are two main claims made in this article. First, that the restrictions Liouville's theorem places on Maxwell's demon's ability to operate depend on which notion of entropy one adopts. Second, that when one operates with the definition of entropy that is usual in this debate, the restrictions put on Maxwell's demon are not even as severe as Albert and Hemmo and Shenker argue.

Recent advances in quantum physics have led to a renewal of interest in the problem of human freedom and in the wider problem of indeterminism. It is important to recognize, however, that if every denial of determinism is to be called indeterminism, the latter term covers a wide range of logically distinguishable positions. We should perhaps speak in the plural number of indeterminisms rather than of indeterminism. For determinism may be defined, simply, as the doctrine that every event has a cause; or we may add that the effect is always uniquely determined; or that when the effect is complex it can always be exhaustively analyzed into components each of which is the effect of a component of the cause; or that every cause directly or indirectly includes the entire universe. And in the case of each of these, or of still other interpretations of determinism, the denial would be a form of indeterminism.

The naive misunderstanding among economists of the relationship between economics and philosophy is as profound as it is prevalent. To be sure, economists have concerned themselves with the philosophy of economics only so much as to familiarize themselves with methodology and its application to economic inquiry. Since economics is the oldest and perhaps the most “respectable” of the social sciences its scholars have developed a phobia for anything they might suspect to be even remotely unscientific. Consequently, they have erroneously narrowed their understanding of the nature of economics. This narrowness prevails largely because most economists possess little or no training in general philosophy and especially in the philosophy of science. As a result of this apparent deficiency there exists in the minds of these economists confusion and inability to distinguish between teleology, axiology, and ethics as they do or do not apply to economics.

The import of Hodgkin and Huxley’s classic model of the action potential has been hotly debated in recent years, with particular controversy surrounding claims by prominent proponents of mechanistic explanation. For these authors, the Hodgkin-Huxley model is an excellent predictive tool but ultimately lacks causal/explanatory import. What is more, they claim that this is how Hodgkin and Huxley themselves saw the model. I argue that these claims rest on a problematic reading of the work. Hodgkin and Huxley’s model is both causal and, in an important sense, explanatory.

I consider a way the concept of causation could be excised from chemical practice, suggested by Kitcher's view that causes are just a subset of unifying patterns which play a particular psychological role for us. Kitcherian chemistry is at first blush well equipped to handle explanatory tasks. However, it would force chemists to accept certain unifying patterns as explanatory, which they do not think are at all explanatory. This might head off some descriptive lines of enquiry and damage prospects for the identification of potentially larger-scale explanations. More important than this, to chemists, it could put them off from finding the explanatory patterns that are true—true because they get at the real structure of the chemical phenomena in the world.