First, ranking functions are argued to be superior to AGM belief revision theory in two crucial respects. Second, it is shown how ranking functions are uniquely reflected in iterated belief change. More precisely, conditions on threefold contractions are specified which suffice for representing contractions by a ranking function uniquely up to multiplication by a positive integer. Thus, an important advantage AGM theory seemed to have over ranking functions proves to be spurious.

This is a position paper concerning the role of empirical studies of human default reasoning in the formalization of AI theories of default reasoning. We note that AI motivates its theoretical enterprise by reference to human skill at default reasoning, but that the actual research does not make any use of this sort of information and instead relies on intuitions of individual investigators. We discuss two reasons theorists might not consider human performance relevant to formalizing default reasoning: (a) that intuitions (...) are sufficient to describe a model, and (b) that human performance in this arena is irrelevant to a competence model of the phenomenon. We provide arguments against both these reasons. We then bring forward three further considerations against the use of intuitions in this arena: (a) it leads to an unawareness of predicate ambiguity, (b) it presumes an understanding of ordinary language statements of typicality, and (c) it is similar to discredited views in other fields. We advocate empirical investigation of the range of human phenomena that intuitively embody default reasoning. Gathering such information would provide data with which to generate formal default theories and against which to test the claims of proposed theories. Our position is that such data are the very phenomena that default theories are supposed to explain. (shrink)

Adams famously suggested that the acceptability of any indicative conditional whose antecedent and consequent are both factive sentences amounts to the subjective conditional probability of the consequent given the antecedent. The received view has it that this thesis offers an adequate partial explication of Ramsey’s test, which characterizes graded acceptability for conditionals in terms of hypothetical updates on the antecedent. Some results in van Fraassen may raise hope that this explicatory approach to Ramsey’s test is extendible to left-nested conditionals, that (...) is, conditionals whose antecedent is itself conditional in form. We argue that this interpretation of van Fraassen’s results is to be rejected. Specifically, we provide an argument from material inadequacy against a generalization of Adams’ thesis for left-nested conditionals. (shrink)

It is a pleasure for me to give this opening address to the Royal Institute of Philosophy Conference on ‘Explanation’ for two reasons. The first is that it is succeeded by exciting symposia and other papers concerned with various special aspects of the topic of explanation. The second is that the conference is being held in my old alma mater, the University of Glasgow, where I did my first degree. Especially due to C. A. Campbell and George Brown there was (...) in the Logic Department a big emphasis on absolute idealism, especially F. H. Bradley. My inclinations were to oppose this line of thought and to espouse the empiricism and realism of Russell, Broad and the like. Empiricism was represented in the department by D. R. Cousin, a modest man who published relatively little, but who was of quite extraordinary philosophical acumen and lucidity, and by Miss M. J. Levett, whose translation of Plato's Theaetetus formed an important part of the philosophy syllabus. (shrink)

The theory of forms makes a very poor theory of universals. It-or at least the "phaedo's" version of it-makes excellent sense as a theory of the elemental stuffs from which everything is made. This is shown by a detailed examination of all that this "phaedo" has to say about forms.

David Hull's (1988c) model of science as a selection process suffers from a two-fold inability: (a) to ascertain when a lineage of theories has been established; i.e., when theories are descendants of older theories or are novelties, and what counts as a distinct lineage; and (b) to specify what the scientific analogue is of genotype and phenotype. This paper seeks to clarify these issues and to propose an abstract model of theories analogous to particulate genetic structure, in order to reconstruct (...) relationships of descent and identity. (shrink)

The paper examines the role played by the notion of truth in the version of scientific realism known as scientific entity realism. Scientific entity realism is the thesis that the unobservable entities postulated by scientific theories are real. As such, it is an ontological thesis about the existence of certain entities. By contrast, scientific realism is often characterised as a thesis primarily involving the truth of theories. Sometimes scientific realism is expressed as the thesis that theoretical statements are intended as (...) true descriptions of reality. Another favoured theme is that theoretical statements are objectively true or false in virtue of the way the world is independently of us. To such formulations it is usually added that the sense of 'true' required by scientific realism is the correspondence sense. To mark the contrast with scientific entity realism, I shall say that a formulation of scientific realism in terms of truth is a semantic version of scientific realism. [For footnotes, see The Semantic Stance of Scientific Entity Realism Corrigenda in Philosophia 25 3-4 1997 481-482]. (shrink)

These are the footnotes for the article which was published in Philosophia Vol 24 1995, pp. 405-415.

I will discuss those epistemic accounts of truth that say, roughly and at least, that the truth is what all ideally rational people, with maximum evidence, would in the long run come to believe. They have been defended on the grounds that they can solve sceptical problems that traditional accounts cannot surmount, and that they explain the value of truth in ways that traditional (and particularly, minimal) accounts cannot; they have been attacked on the grounds that they collapse into idealism. (...) I show that all these claims are mistaken. The system of statements accepted by an adherent of an epistemic account who also accepts the equivalence scheme is the same as that accepted by an adherent of a traditional account who also accepts a remarkably strong thesis of epistemic optimism. The singling out of one rather than another claim within this system as defining 'true' cannot make as much difference as to imply idealism or refute scepticism. However, it can make all the difference when it is a matter of explaining the value of truth. For a crucial point in such explanation depends on what can be soundly substituted for what in intensional contexts; above all those governed by such verbs as 'know', 'hope', 'believe', 'value'. That is, it depends on what expressions are intensionally equivalent. And one point of singling out one formulation as definitional can be to settle just this. But though some epistemic theorists have deemed ability to explain the value of truth a merit of their account (and lack of this ability a fatal defect of traditional accounts, of minimal accounts in particular), it turns out that minimal accounts of 'true' fit a sound account of our valuing of truth in a way that epistemic accounts do not. In the course of this argument I rebut related positions: e.g. Dummett's, that minimal definitions fail because they cannot account for the point of having a notion of truth, and that an account of the practice of assertion is what would fill this lacuna. I argue to the contrary that if the point of the notion could not be explained on the basis of a traditional definition, it could not be explained at all. (shrink)