Ehsan Javadi

This article delves into Dudley Shapere’s approach to addressing semantic incommensurability, focusing on the “chain of reasoning connection.” We will start by reviewing the concept of incommensurability and its various types. Then, we will take a closer look at semantic incommensurability. Before examining Shapere’s solution, we will explore his thoughts on the history and philosophy of science. To understand the chain of reasoning connection, we introduce the traditional theory of meaning and the causal theory of reference and Shapere’s criticisms of them. We will investigate how reasoning chains originating from existing theories can create a connection between them and alternative theories, potentially bridging the gap between their terms. Shapere suggests that two distinct usages of a term in existing and new theories are linked through a chain of reasoning. While some or all descriptions may alter in this process, all changes are traceable through reasons. Lastly, we will present two historical examples that illustrate the challenges faced by the chain of reasoning solution. Shapere emphasizes that a chain of reasoning links existing and new theories to prevent incommensurability. However, issues arise when a new theory emerges from a rejected one. We will present a case in the history of optics. Also, we will demonstrate that the “chain of reasoning” solution to semantic incommensurability relies on scientific consensus and challenges its efficiency by presenting a case in the history of chemistry. Finally, we will highlight how Shapere’s argument is an obstacle to identifying concept relations in a theory or paradigm. Introduction In this paper, we will discuss Thomas Kuhn’s idea about the incommensurability of scientific theories. There are three types of incommensurability: observational, methodological, and meaning or semantic incommensurability. We will focus more on the meaning or semantic incommensurability in this article because of its significance in Kuhn’s latest work. Meaning or semantic incommensurability occurs when a change in scientific paradigm leads to alterations in the language and meaning of scientific terms. Terms and concepts that have specific meanings within one paradigm may acquire new, potentially incommensurable meanings in another. We will introduce the later works of Thomas Kuhn. In his latest work, Kuhn stated that meaning incommensurability arises among certain terms in competing theories or paradigms. Philosophers and historians of science have extensively responded to Kuhn’s theory in The Structure of Scientific Revolutions and the controversial issue of the incommensurability of scientific paradigms. Among them, American philosopher Dudley Shapere has endeavored to find a resolution to this issue. This article presents his perspectives on these subjects and then discusses his proposed solution for the issue of meaning or semantic incommensurability. Shapere suggests that by tracing the “chain of reasoning” that leads to changes in the meaning of vocabularies in scientific theories, the problem of meaning incommensurability could be resolved. In this paper, we present three critiques of his argument or solution for the problem of meaning incommensurability. We provide two historical cases in science that demonstrate how the chain of reasoning in some instances cannot hinder the issue of meaning or semantic incommensurability. The third critique challenges the argument against essentialism, emphasizing that Shapere’s position overlooks the vital role of structural or essential properties in influencing the connections between scientific concepts within a specific theory or paradigm. Body In the introduction, we examine Dudley Shapere’s views on the philosophy of science, particularly his solution to the problem of meaning or semantic incommensurability. Shapere’s philosophy of science is based on two principles from the history of science: ”rejecting the possibility of predicting nature” and “principle of scientific internalization.” According to Shapere, scientific development is unpredictable, and he rejects any presuppositions about the evolution of scientific research. He emphasizes the internalization and autonomy within the scientific enterprise, suggesting that science gradually modifies its methods and concepts. This process allows for the revision, modification, and abandonment of methodological and substantive concepts within science. Shapere avoids presenting a general presupposition for the scientific activity that impedes explaining changes and developments in science. He considers changing or abandoning theories as a gradual process rather than a revolutionary one. Shapere argues that reasons create a link between the concepts and structures of existing and alternative theories, allowing for commensurability between the concepts of both. He criticizes both the traditional theory of meaning and the causal theory of reference. Shapere posits that supposing essential properties for concepts is the key factor in the emergence of the problem of incommensurability. He advocates a view that focuses on descriptions rather than on the reference, but none of these descriptions are essential or distinguished. Shapere suggests that two distinct usages of a term in existing and new theories are linked through a chain of reasoning. While some or all descriptions may alter in this process, all changes are traceable through reasons. This enables commensurability in meaning. Discussion As noted in the previous section, two critiques are historical case studies, and the third critique addresses Shapere’s arguments against essentialism. Shapere’s argument emphasizes that a chain of reasoning links existing and new theories to prevent incommensurability. However, issues arise when a new theory emerges from a rejected one, leading to disconnected chains of reasoning and incommensurability. For instance, in the 17th century, Newton’s particle theory clashed with Huygens’s wave theory in explaining light’s nature. Newton’s theory became dominant in the 18th century, but a paradigm shift occurred in the 19th century with Thomas Young’s experiments, leading to the acceptance of Huygens’s wave theory. Notably, the alternative theory did not originate from the existing dominant theory but from a previously rejected theory. The “chain of reasoning” solution to semantic incommensurability relies on scientific consensus. When scientists accept a new theory, it bridges the gap between old and new concepts. However, disagreements within the scientific community can lead to the rejection of the “chain of reasoning,” hindering the transition to new theories. This is illustrated by the contrasting views of Joseph Priestley and Antoine Lavoisier on a newly discovered gas. Priestley saw it as “dephlogisticated air,” while Lavoisier identified it as oxygen. This difference in reasoning led to semantic incommensurability between their theories. Shapere proposes that the meaning of a concept is composed of a set of characteristics or properties. Changing the meaning of a concept involves adding or dropping one or more properties based on a reasoning process relevant to the problem at hand. These properties are not essential or necessary. Shapere acknowledges that some properties (structural properties) of natural entities are more prominent than others, but this does not mean they are essential or necessary. However, even though these properties can change, it is done through a chain of reasoning. Therefore, the change in the meaning of concepts by adding or removing a property is not considered a revolutionary change in meaning. Consequently, changes in the meaning of both new and old concepts will not cause semantic incommensurability. However, structural or essential properties are crucial as they establish hierarchical relationships among concepts and related examples. Change of core properties or inherent features can lead to semantic incommensurability, even if there is assumed continuity through a reasoning chain. Conclusion In this paper, we reviewed the meaning or semantic incommensurability problem in Thomas Kuhn’s works and then surveyed Dudley Shapere’s response to this issue, specifically his work The Chain of Reasoning, which is based on his perspective on the philosophy and history of science. As demonstrated in the final section, certain historical scientific cases do not align with Shapere’s framework regarding scientific evolution and his proposed resolution for the meaning or semantic incommensurability problem, leading to a resurgence of this issue. Furthermore, our analysis indicates that the refusal to acknowledge the existence of essential and intrinsic characteristics for concepts does not impede semantic incommensurability.

Introduction The Publication of Kuhn’s influential book The Structure of Scientific Revolutions is one of the most important points in the history and philosophy of science studies and has raised many debates among philosophers and historians of science. One of the most interesting implications of Kuhn’s thesis is the incommensurability of scientific paradigms and its related concepts. Paul Thagard is one of the philosophers who reacted to Kuhn’s incommensurability thesis and tried to show how, by appealing to cognitive computational theories, the incommensurability problem could be resolved. In this essay, after introducing Thagard’s Conceptual Change Theory and review of one case study, we will survey the implications of Thagard’s theory on scientific growth and the history of science and present two critiques. Summary In this essay, in the first part, we have tried, by the introduction of concept constituents and representation based on Thagard’s Computational Philosophy of Science to show how he explains conceptual changes and revolutions in the history of science. Thagard considered concepts as complex structures like neurons in neural networks which are organized in kind and part hierarchies and relating to each other by relevant weight. Thagard described four types of relations between replacement and substituent theories: incorporation, sublation, supplantation, and disregard. Sublation and supplantation are the important types of theory change processes that have been introduced by Thagard to describe scientific revolution. If T1 partially incorporates T1 while rejecting aspects of T1, then T2 sublatesTl and if T2 involves the near-total rejection of TI, then T2 supplants T1. As Thagard claimed, other than disregard, all of the other three types of scientific theory change accept some degree of cumulating in substituent theory. As we have reviewed in Thagard’s case studies, which he referred to as radical conceptual revolutions; such as Lavasiour and Darwin’s revolution, there is at least some amount of evidence and method cumulating in substituent theory. On the other hand, it could be interpreted that Thagard somehow accepted the semantic holism theory. In this paper, an argument has been posed which shows that these two claims are contradicted. The premises and conclusions of the argument are shown as below: 1. According to the holism theory of meaning, the meanings of concepts are determined by their relation in a conceptual web or hierarchy. 2. It could be interpreted that Thagard confirmed the holism theory of meaning. 3. Scientific Revolutions –either occurring as sublation or supplantation way – make dramatic changes in the conceptual hierarchy of existing theory in comparison with substituent theory. 4. Thagard declared that in the dramatic scientific revolution, there are at least some method and concepts 5. Thagard stated that evidence could be evaluated independently. In other words, he denies the theory dependency of evidence. 6. Premises1, 2 and 3 are contradicted by 4 and 5. Because, by accepting the holism theory of meaning, there is no way to evaluate apparent common evidence of rival theories independently without considering their relation to existing and substituent theories. Thagard and some other philosophers like Nancy Nersissian claimed that Thomas Kuhn’s mistake is that he has not considered the gradual nature of conceptual changes which has been revealed with the help of cognitive science. They believe that in the theory change stage a gestalt shift is not occurring as Thomas Kuhn thought, for practitioners and advocates of existing and substituent theories or paradigm’s, so there is not a sharp and clear boundary between rival theories and advocates of each theory could realize each other’s experiments. As a final point, we will show by review of a historical case – the Quantum Mechanic revolution- that the gradual nature of scientific change would not imply that there is not a boundary at all and in principle it could be conceived a final point -albeit not clear- existing theory totally replaced by substituent theory and practitioners of new theory conform their mind by the exemplar, method and tradition of a new theory. Conclusion In this paper, we study Thagard’s theory concerning concept structure, representation, and conceptual change. After review of an important case study, we reviewed four types of possible relations between existing and substitute theories. As it has been shown, Thagard believed that at least evidence and methods accumulation take place even in radical revolutionary theory change. By providing an argument, we have tried to show that the holism theory of meaning, which seems to be accepted by Thagard, is contradicted by evidence accumulation. On the other hand, by reviewing a historical case-study we have tried to show that Thagard’s argument against the gestalt shift theory of Kuhn, is confronted by a problem.