This paper presents a representational theory of derived physical measurements. The theory proceeds from a formal definition of a class of similar systems. It is shown that such a class of systems possesses a natural proportionality structure. A derived measure of a class of systems is defined to be a proportionality-preserving representation whose values are n-tuples of positive real numbers. Therefore, the derived measures are measures of entire physical systems. The theory provides an interpretation of the dimensional parameters in a (...) large class of physical laws, and it accounts for the monomial dimensions of these parameters. It is also shown that a class of similar systems obeys a dimensionally invariant law, which one may safely subject to a dimensional analysis. (shrink)

This article begins with an introduction to defeasible (nonmonotonic) reasoning and a brief description of a computer program, EVID, which can perform such reasoning. I then explain, and illustrate with examples, how this program can be applied in computational representations of ordinary dialogic argumentation. The program represents the beliefs and doubts of the dialoguers, and uses these propositional attitudes, which can include commonsense defeasible inference rules, to infer various changing conclusions as a dialogue progresses. It is proposed that computational representations (...) of this kind are a useful tool in the analysis of dialogic argumentation, and, in particular, demonstrate the important role of defeasible reasoning in everyday arguments using commonsense reasoning. (shrink)

This article argues that: (i) Defeasible reasoning is the use of distinctive procedures for belief revision when new evidence or new authoritative judgment is interpolated into a system of beliefs about an application domain. (ii) These procedures can be explicated and implemented using standard higher-order logic combined with epistemic assumptions about the system of beliefs. The procedures mentioned in (i) depend on the explication in (ii), which is largely described in terms of a Prolog program, EVID, which implements a system (...) for interactive, defeasible reasoning when combined with an application knowledge base. It is shown that defeasible reasoning depends on a meta-level Closed World Assumption applied to the relationship between supporting evidence and a defeasible conclusion based on this evidence. Thesis (i) is then further defended by showing that the EVID explication of defeasible reasoning has sufficient representational power to cover a wide variety of practical applications of defeasible reasoning, especially in the context of decision making. (shrink)

In Structures in Science, Theo A. F. Kuipers presents a detailed analysis of reductive, including microreductive, explanations. One goal of a microreduction is to explain the laws governing a structured object in terms of laws about its parts, plus a description of its structure. Kuipers refers to structures in his book, and uses the idea of a "structure representation function," but does not characterize the relevant concept of structure. To characterize microreductions fully, we need an adequate characterization of the relevant (...) sense of "structure." After discussing examples, I present general analyses of bonds and of structured wholes. My analyses apply from physics to the social sciences, the latter illustrated by a hypothetical robotic social structure. Since Kuipers' philosophical position appears to be generally compatible with my own, I do not critique of any part of his work. Instead, this article is intended to fill in a gap in his presentation. (shrink)

Discussions of unified science frequently suppose that the various scientific theories should be combined into one unified theory, and it is usually supposed that this should be done by successive reductions of the various theories to some fundamental theory. Yet, there has been little systematic study of the characteristics of unified theories, and little foundational support for the use of reductions as a unifying procedure. In this paper I: (a) briefly review some of my previous work on microreductions, (b) state (...) some conditions which are necessary in order for a theory to be unified, (c) argue that when certain identities exist between the elements in the domains of two theories, then the only satisfactory way to combine these two theories into one unified theory is by a micro-reduction, and (d) indicate briefly some further applications and consequences of this work. (shrink)