This paper examines commonly offered arguments to show that human behavior is not deterministic because it is not predictable. These arguments turn out to rest on the assumption that deterministic systems must be governed by deterministic laws, and that these give rise to predictability “in principle” of determined events. A positive account of determinism is advanced and it is shown that neither of these assumptions is true. The relation between determinism, laws, and prediction in practice is discussed as a question in scientific epistemology.

Several philosophers of science have claimed that the conceptual difficulties of quantum mechanics can be resolved by appealing to a particular interpretation of probability theory. For example, Popper bases his treatment of quantum mechanics on the propensity interpretation of probability, and Margenau bases his treatment of quantum mechanics on the frequency interpretation of probability. The purpose of this paper is (i) to consider and reject such claims, and (ii) to discuss the question of whether the ψ-function refers to an individual system or to an ensemble of systems.

In the first part of this paper, two arguments, one by Chomsky, and one by Bar-Hillel and Shamir, are examined in detail and rejected. Both arguments purport to show that the structure of English precludes its having a finite state grammar which correctly enumerates just the well formed sentences of English.

In the latter part of the paper I consider the problem of supporting claims about the structure and properties of a natural language when no grammar for the language has yet been accepted.

Recent discussion of the problem of the conclusive falsification of scientific hypotheses has generally regarded the Duhemian Thesis (D-Thesis) as both true and interesting [10] but has dismissed the claim that disconfirmed hypotheses can be retained in explanations of the disconfirming evidence as either trivial [3] or unargued [12]. This paper rejects these positions. First, the status, in the argument for the D-Thesis, of the claim that auxiliary assumptions are necessary for the derivation of evidential propositions from hypotheses is examined. It is concluded that depending on this status, the D-Thesis is either trivially true or unargued. Then the retention of contextually disconfirmed hypotheses is discussed. It is found that the use of such hypotheses in explanations of the disconfirming evidence is mediated by principles of scientific methodology. A new thesis is presented connecting the problem of conclusive falsification with changes in methodology. The argument for this thesis introduces a new analysis of methodological principles as inductive generalizations from scientific practice. Finally, the contribution of this analysis to the understanding of scientific change is described.

A belief common among philosophers and biologists alike is that Mendelian genetics has been or is in the process of being reduced to molecular genetics, in the sense of formal theory reduction current in the literature. The purpose of this paper is to show that there are numerous empirical and conceptual difficulties which stand in the way of establishing a systematic inferential relation between Mendelian and molecular genetics. These difficulties, however, have little to do with the traditional objections which have been raised to reduction.

Wesley Salmon has advanced a new model of explanations of particular facts which requires that the explanans contain laws. The laws used in explanations (according to this model) are of the form P(A · C1, B) = p1 ... P(A · Cn, B) = pn. A condition imposed by Salmon on these laws is that the reference classes, i.e. A · C1 ... A · Cn, be homogenous with reference to the property B. A reference class A is homogenous with reference to a property B if every property which determines a place selection with reference to B within A is statistically irrelevant to B in A. It is argued here that the concept of homogeneity cannot in general be satisfied in scientific explanations and that even a weaker requirement, “epistemic homogeneity,” may be too strong.

Building on two nonproblematic claims, I argue for a qualified endorsement of Hume's intuition that there must be a time-difference between cause and effect. Those claims are: (i) that the statement ‘A caused B’ is meaningful only if we have a criterion for saying ‘A’ and ‘B’ refer to distinct events; and (ii) that an adequate view of what it is to be an event must illuminate the enterprise of seeking to establish a singular causal statement. Specifically, I argue there must be a time-difference when cause and effect are modifications of the same physical object.

Michael Ruse has offered an interesting and insightful analysis of function statements in biology. The analysis he gives of statements of the form ‘The function of x in z is to do y‘ is :

1. (i) z does y by using x.

2. (ii) y is an adaptation ([4], p. 91).

The first thing to notice about this formulation is the peculiarity of step (ii). There are many cases in which we would naturally say that x was the adaptation, instead of y; or perhaps we might say that everything asserted in step (i) constituted the adaptation. For example, the function of the duck's webbed feet is to enable it to swim. But we would commonly and naturally say that the adaptation was the webbing, not the swimming. It seems to me that Ruse's insistence on the formulation in (ii) points to the major difficulty of his analysis : and understanding what drives him to this unnatural formulation suggests the way out of those difficulties.

Professor Stevenson's valuable paper [5] calls attention to a number of discrepancies between ‘if’ in English and its usual translation into the horseshoe of material implication. “This is not a reason for distrusting the horseshoe,” he notes, “which is useful so long as it is taken to mean just what it is defined to mean; and it is not a reason for distrusting our English if's, which in spite of their ambiguities are indispensable to our daily discourse” ([5], p. 27). Accordingly, Stevenson proposes to develop a “richer logic” than the ordinary one, by adding as primitives certain sentential connectives. He speaks throughout in the old terminology of “propositions” rather than in that of the sentences or statements used to express them. Thus he speaks of atomic and molecular propositions, somehow no doubt as real entities in the world, where talk of atomic and molecular sentences would save him from implicit involvement in the notorious difficulties connected with atomic facts. Finally, the inner structure of atomic sentences, and therewith of molecular ones, is never considered. Many molecular sentences contain quantifiers in interesting ways, the clarification of which would seem essential in getting at their structure. Stevenson, however, has no concern with quantifiers, and does not exhibit the quantificational structure of the English sentences considered.

(1) The probability of some generalizations can be lowered by positive instances.

(2) The change in probability (both degree and direction) can depend on factors other than the new evidence, the statement, and the probability of the statement given the old evidence.

Professor Copi provides us with the following example:

In successive issues of this journal Ronald Munson [2] and I [4] have made, quite independently, conflicting claims about the relationship between biological adaptation and biological function. I state, admittedly without proof, that “a functional statement in biology draws attention to the fact that what is under consideration is an adaptation or something which confers an ‘adaptive advantage’ on its possessor” ([4], p. 89). This was an identity claim. Munson claims, with proof, that “adaptation and function are not identical” ([2], p. 205). In this discussion note I want to examine the three arguments Munson gives in support of his claim, and I shall try to show that they do not hold.

Michael Ruse [3] has criticized the distinction between biological function and evolutionary adaptation that I argued for in my article “Biological Adaptation” [2]. I shall show below that Ruse's criticisms are not, for the most part, well taken and that the distinction remains as I made it.

The problem of idealization in empirical sciences is very rarely taken up in works concerned with the methodology of those sciences. It seems to be common knowledge that in advanced natural sciences references are made to concepts such as “perfectly rigid body,” “material point,” “perfect gas,” etc., but it remains a fact that the most important methodological concepts, concepts which have determined the present-day form of the philosophy of science, have been advanced without regard to the peculiarities of the procedure mentioned above. And yet a moment's consideration suffices to raise doubts as to Carnap's physicalism and/or Popper's falsificationism if we just realize the trivial and commonly known truth that empirical sciences resort to idealizationism. For how are we to imagine a reduction of idealizational concepts to observation terms? And how are we to imagine that theorems which include idealizational concepts imply observation statements which refute, or at least are at variance with, those theorems? But it is a fact that such doubts have neither been raised by the authors of the conceptions mentioned above, nor have they been raised (as far as the present writer is informed) against them.