Abstract
First, a brief state of the art on the role of values in science is presented. The main points of the critique of the ideal of a free-value science are depicted (Sec. 2), followed by a framework of four phases in the development of scientific activity that allows us to better assess the influence of values in science. The basic thesis of the present text criticizes the conception close to Heather Douglas’ thesis, according to which values, including cognitive values, can only play an indirect role in science (Sec. 3). In order to show that, at certain phases of science, the explanatory power (a cognitive value) can play a direct role, we propose an examination of structural explanation, as distinguished from mechanistic explanation, in a case of experimental linguistics related to language acquisition (Sec. 4). The conclusion is presented in the last section.