Mohamed Elsamahi

A Critique of Localized Realism Abstract In an attempt to avert Laudan’s pessimistic induction, Worrall and Psillos introduce a narrower version of scientific realism. According to this version, which can be referred to as “localized realism”, realists need not accept every component in a successful theory. They are supposed only to accept those components that led to the theory’s empirical success. Consequently, realists can avoid believing in dubious entities like the caloric and ether. This paper examines and critiques localized realism. It also scrutinizes Psillos’s historical study of the caloric theory of heat, which is intended to support localized realism.

Hacking and other entity realists suggest a strategy to build scientific realism on a stronger foundation than inference to the best explanation. They argue that if beliefs in the existence of theoretical entities are derived from experimentation rather than theories, they can escape the antirealist's criticism and provide a stronger ground for realism. In this paper, an outline and a critique of entity realism are presented. It will be argued that entity realism cannot stand as a separate position from classical realism. Thus, entity realism cannot avoid the problems facing classical realism.

This paper argues that conceptual factors are as important as empirical factors in theory acceptance. Coherence between a new theory that is assessed for acceptance and the existing (established) theories in the same domain is among such conceptual factors. For example, a new theory about spectroscopy that does not cohere with established theories of spectroscopy is unlikely to be accepted, even if it was supported by empirical considerations. It is argued that a new theory coheres with a group of established theories when it shares important elements with these theories and contains no items that conflict with their central concepts and assumptions.

Conceptual merits of a theory are important for its acceptance. According to the traditionally held view, theory acceptance depends mainly on empirical support or confirmation. This paper argues that a new theory has also to cohere with already accepted theories to be accepted. In other words, confirmation alone is insufficient for acceptance. Coherence, like simplicity and internal consistency, is a conceptual merit. Coherence between theories, according to this paper, consists in agreement on the main concepts and mutual support. That is, two theories cohere with each other when they do not differ on the principal notions and assumptions and also provide support for each other.

Hacking and other entity realists suggest a strategy to build scientific realism on a stronger foundation than inference to the best explanation. They argue that if beliefs in the existence of theoretical entities are derived from experimentation rather than theories, they can escape the antirealist's criticism and provide a stronger ground for realism. In this paper, an outline and a critique of entity realism are presented. It will be argued that entity realism cannot stand as a separate position from classical realism. Thus, entity realism cannot avoid the problems facing classical realism..

If scientific theories could be known to be true, theory acceptance would be based on the truth of theories: we would accept only true theories. But no theory can be known to be true, as will be argued in chapter 4. I argue that the main determinant of acceptance is the ability of a theory to cohere with other accepted theories. Yet intertheoretic coherence is not the only determinant of acceptance. Accepted theories should be well-constructed and have an explanatory capability to be accepted. Intertheoretic coherence also constrains theory change, as will be argued in chapter 6. The widely accepted view that the principal aim of science is to provide adequate explanations is defended in this dissertation. However, adequate explanations do not have to be true, it will be argued. This, nonetheless, does not undermine the rationality of science. Science is rational as long as it gives us the best possible explanation with the help of the best available theories. ;The plan of the dissertation is as follows. In first two chapters, a review and critique of scientific realism is offered, because its basic theses are at variance with the coherentist view. It is shown that the realist view of theory acceptance and change is untenable. In chapter 3, Hacking's attempt to defend realism by founding its basic tenets on experimentation, will be criticized. Chapter 4 is concerned with the applicability of theories of truth to scientific theories. It is argued that no theory of truth can enable us to know whether a scientific theory is true. As an introduction to the view that the aim of science is to explain, I argue that predictions are special forms of explanation in chapter 5. In chapter 6, the main arguments for the coherentist view, which are supported by historical case studies, are presented. Also, it is argued that science is objective. Chapter 7 advocates the view that science aims primarily to produce explanations. The traditional view science can be rational only if its explanations are known to be true, not merely adequate, will be criticized