The official model of explanation proposed by the logical empiricists, the covering law model, is subject to familiar objections. The goal of the present paper is to explore an unofficial view of explanation which logical empiricists have sometimes suggested, the view of explanation as unification. I try to show that this view can be developed so as to provide insight into major episodes in the history of science, and that it can overcome some of the most serious difficulties besetting the covering law model.

The article responds to some of the points raised by B. van Fraassen concerning probability kinematics and direct inference within the framework of the approach to the revision of probability judgment proposed by Levi in The Enterprise of Knowledge. In particular, the critical importance of the question of direct inference is emphasized and explained.

The present trend towards an atheoretical statistical method of psychiatric classification has prompted many psychiatrists to conceive of “mental disorder”, or for that matter any other psychopathological designation, as an indexical cluster of properties and events more than a distinct psychological impairment. By employing different combinations of inclusion and exclusion criteria, the current American Psychiatric Association's scheme (called DSM-III) hopes to avoid the over-selectivity of more metaphysical systems and thereby provide the clinician with a flexible means of dealing with a wide diversity of cases. In the hope of redirecting future inquiry, the paper will argue: (1) that this recent trend might appear to be clinically beneficial, but in point of fact it is riddled by unsound theoretical conclusions which leave the field without a deeply reaching base for understanding and treating mental disorder, and (2) that, a fortiori, “mental disorder” is best conceived as not a cluster of properties and events, nor a metaphorical reaction to a breakdown in social interpersonal relations, but as a deeply laid condition characterized by the absence of an imaginally integrated system.

Hobbes' philosophy of geometry was eccentric to contemporary movements and worsted in specific controversy. But he laid down stipulations defining geometry and its method which might provide a significant and workable alternative “meta-geometry”. Some of these are isolated and reinterpreted here, especially those concerned with describing magnitudes, motions and quantities, and with his use of proportions. Rather than refutation of commentaries and historical rehash, the effort here is to isolate definitive texts and to offer a reinterpretation of their arguments in succinct form showing their coherence and their interdependence with his other philosophic principles.

A previous paper of mine, that criticized Suppes' probabilistic theory of causality, was in turn criticized by Deborah Rosen. This paper is a development of my argument and an answer to Rosen. It is argued that the concept of causation is used in contemporary science in a way that presupposes determinism. It is shown that deterministic assumptions are necessary for inferences from generic to individual causal relations and for various kinds of eliminative arguments.

In this paper I show that Goodman's theory of projectibility, although partly successful, is inadequate since it fails to take into consideration the “approximate” nature of certain scientific hypotheses.

Barker and Achinstein misread Goodman's definitions of ‘grue’ and ‘bleen’. If we stick to Goodman's definition of ‘grue’ as applying “to all things examined before t just in case they are green but to other things just in case they are blue” (my italics), and his parallel definition of ‘bleen’, then Barker and Achinstein's arguments are seen to be irrelevant. The result is to by-pass the question whether Mr. Grue sees things as grue rather than as green while showing that it is possible for human conceptual schemes to employ different sensory terms. These two issues are separate.