The present paper analyzes Edna Ullman-Margalit's contribution for the development of a philosophical concept of presumption (assume from the occurrence of a known fact the occurrence of an unknown fact in order to act on its basis). Ullman-Margalit takes the legal context as a departure point for her theory because she believes that technical legal language is more precise than ordinary language in relation to the concept of "presumption" and its terminological cousins. Given that her 1983 paper has been a reference to those who attempt to understand what it means to "presume", this paper will offer two objections to Ullman-Margalit's contributionEl presente paper analiza la contribución de Edna Ullmann-Margalit al desarrollo del concepto ...