1 Marcin Trybulec RATIONALITY IN THE MATERIAL WORLD ABSTRACT: Modeling the relationship between cognitive artifacts and rationality is the central issue with which this paper is concerned. In the research on cognitive artifacts, two models of the relationship between cognition and artifacts can be identified: the amplification model and the transformation model. It is argued that the amplification model leads to trivial conclusions about the role of artifacts for cognition. The transformation model provides an insightful perspective on cognitive artifacts, but needs to be submitted to careful scrutiny. Research on problem solving is used in order to make the advantages of the transformation model explicit. Key words: cognitive artifact, transformation model, amplification model, problem solving, rationality, task environment, problem space, physical constraints for problem solving. 1. Introduction The idea of the significance of material tools for cognition seems to be deeply rooted in the tradition of Western thought. Bacon (Bacon [1620] 2012) aptly expressed the importance of tools and artifacts in Novum Organum: Neither the naked hand nor the understanding left to itself can effect much. It is by instruments and helps that the work is done, which are as much wanted for the understanding as for the hand. And as the instruments of the hand either give motion or guide it, so the instruments of the mind supply either suggestions for the understanding or cautions (book I, section 2, p. 9) Daniel Dennett recently made the same point: "A naked human mind – without paper and pencil, without speaking, comparing notes, making sketches – is first of all something we have never seen" (1997 p. 153). The claim that technology is an indispensable aspect of human thought and action is also a core principle of twentieth century philosophical anthropology. This claim stems from the fact that, when viewed from a biological and evolutionary perspective, the human species is imperfect and incapable of surviving without external props, tools and symbolic systems (Herder 2002; Gehlen 1988). Despite that, the role that material artifacts play in rationality is in large part underestimated by mainstream humanities and social sciences. Penultimate version of the paper published in: Poznań Studies in the Philosophy of the Sciences and the Humanities, Brill, Leiden 2018, s. 296 – 313, ISSN: 03038157