The volume edited by Joël Biard and Fosca Mariani Zini investigates the philosophical profiles of Dante, Petrarch, and Boccaccio. Three recurring themes emerge: the implicit claim to elevate poetry to a scientific status among the arts through a continuous dialogue in imitation and competition with philosophy, the defense of poetry as the true language of knowledge, and the preeminence attributed to poetry in the field of moral philosophy as a consequence of the thirteenth-century turn toward practical philosophy.

Five articles concentrate on Dante. Irène Rosier-Catach sets Dante's linguistic theory in the De Vulgari Eloquentia within the medieval philosophical debate on language. Unlike Aquinas, Albert the Great, and Ockham, Dante defined locutio as expression of the will to communicate through sensible means, thus specific to human beings. Laurent Gerbier returns to the question of language from a historical perspective, presenting Machiavelli's (attributed) Discorso as a political reading of Dante's theory of illustrious vernacular as “mixed” language. Machiavelli saw in the linguistic mixtio a mirror image of the Italian political situation, where diversity was a strength rather than a weakness. Christophe Grellard's brilliant essay compares Dante and Nicola Oresme's political philosophies and argumentative methodologies. Whereas Dante exemplarily used historical and literary sources to defend universal monarchy and the providential character of the Roman Empire, Oresme used them to defend his idea of a national state, and Charles V's national sovereignity. Oresme's pragmatic approach left unanswered Dante's main questions on universal peace and international policy. Investigating Dante's philosophical formation, Sylvain Piron suggests evidence of Dante's presence as auditor at the Franciscan Studium at Santa Croce in spring 1295, when he possibly posed two questions on the legitimacy of the study of literature in view of intellectual perfection and earthly beatitude to the Franciscan teacher Peter of Trabibus. Joël Biard contributes to the debate about the discrepancies between the Divine Comedy and the Quaestio de acqua et terra. According to Biard, the Quaestio followed the systematic methodology of the quaestiones disputates as developed by Paris teachers such as Albert the Great, centered on the natural explanation of physical phenomena. As fiction, the Comedy instead accommodated philosophical and theological argumentations. Graziella Federici Vescovini valuably contributes to the reconstructing and updating of Dante's astronomical knowledge. Focusing on the Convivio, she suggests that Campano da Novara's Theorica planetarum and Peter of Abanus's Lucidator dubitabilum astronomiae are relevant to Dante for their adaptation of Ptolemaic astronomy to religious needs.

The section on Petrarch stresses the humanistic traits of his thought. Eckhard Kessler reads Petrarch's philology in the light of his orientation toward practical philosophy. Placed between the classical union of wisdom and eloquence and a purely formal approach to texts, philology must be directed to practical life as determined by historical circumstances. Rhetoric and ethics form the two pillars of what Kessler calls Petrarch's “moral philology.” Petrarch's critique of Aristotelian Scholasticism in the De sui ipsius et multorum ignorantia illustrates another aspect of his philosophical turn toward ethics. Christian Trottman shows that in this invective Petrarch affirmed the preeminence of poetry over philosophy as it teaches to love — more than to know — virtue. Both essays seem in line with Eugenio Garin and Charles Trinkaus's philosophical interpretation of humanism, and show the difficulty of interpreting Petrarch's thought within its restrictive definition as “philological” recovery of classical antiquity.

Thomas Ricklin convincingly shows that, by mediating an ideal dialogue between Dante and Petrarch, Boccaccio elaborated an original idea of poetry as no longer dealing with truth but with meaning. Centered on the Genealogie deorum gentilium, the essay shows Boccaccio's independent and provocative thought. Kurt Flasch adds new reflections to his interpretation of Boccaccio as moral philosopher. He argues that the Decameron displays a “lay” ethics adapted to the practical needs of a society shaken by the plague. Fosca Mariani Zini further explores the moral dimension of the Decameron by placing Boccaccio in dialogue with Greek ethics as reinterpreted through Roman Stoicism. While for Cicero earthly goods were desirable in view of moral progress and common good, in a mercantile society they become desirable by themselves. The first nine days of the Decameron delineate an ethics of “surplus” based on self-interest and pleasure. In a sort of palinody, the tenth day illustrates an antithesis to mercantile ethics, and reaches a climax with Griselda's dispossession of the self.

The volume shows the relevance of philosophical inquiry for Dante, Petrarch, and Boccaccio and provides a valuable contribution to the study of their philosophical profiles. Following a humanistic point of view, where ethics acquires preeminence over metaphysics, and rhetoric over logic, the three “crowns” indeed deserve the appellative of poet-philosophers.