A Study of Paul Thagard’s Conceptual Change Theory and its Results on Scientific Progress

Conceptual change and its effects of the history of science has always been one of the challenges issues in historical and philosophical discussions of science. In this paper, we will first introduce Paul Thagard, one of the advocates of Philosophy of Computational Science regarding the essence and circumstances of conceptual change; based on this, we will indicate his approach to the history of philosophy in respect to its being accumulative or revolutionary. According to Thagard, evidence and methods are the least common things which are common in scientific revolutions between an existing and replacement theory. In this article, we will show that this claim does not seem to be compatible with Thagard’s semantic holistic approach. Similarly, through historical case studies regarding Quantum Mechanics scientific revolutions in the history of physics, we will show that contrary to Thagard’s theory, gradualness and overlap of an existing and substituent theory is not proof of cohesion between the two because even though one cannot find a precise boundary between them; this, however, does not mean that there is none and principally, the existing theory has been set aside and the replacement theory has been established.