This interdisciplinary PhD project investigates the significance of the Italian Renaissance humanist Isotta Nogarola (1418–1466) who was one of the first female thinkers to present a defence of the female sex in the dialogue De pari aut impari Evae atque Adae peccato (1451). The philosophical-theological relevance of her literary work for the so-called “Querelle des femmes”, the gender debate that emerged in the 15th century, has not yet been thoroughly highlighted in research. As part of the reappraisal of female thinkers, which has been neglected for many years, this work aims to contribute to anchoring Isotta Nogarola as a woman philosopher and theologian in the history of philosophy and theology. In order to reveal the significance of her philosophical-theological contribution to the gender debate in the context of her time, a re-lecture of the dialogue “Of the Equal or Unequal Sin of Adam and Eve” through the method of Close Reading, which is a detailed textual analysis, is necessary. Here, one the one hand, the investigation of the argumentation, which is characterised by a way of thinking that is progressive for its time and challenges medieval tradition, is of particular interest. On the other hand, the multi-layered intention of the dialogue, which is controversially discussed in research, must be disclosed. Regarding form and mode of argumentation, the historical, cultural, and intellectual context, from whose boundaries her philosophising cannot be detached, must be considered. Furthermore, some focus will be on Isotta Nogarola’s reception during and after her period of writing, which has received little attention in previous research. However, this can provide decisive clues on her pioneering work for the development of the gender debate. This PhD project aims to restore Isotta Nogarola’s significance, which has been largely forgotten in the history of philosophy and theology.