Calcoli simbolici e metodi inventivi. L'incidenza dei sensi della vista e dell'udito nei rapporti della logica con la retorica fra il XVII e il XVIII secolo

The paper examines the relation between logic and rhetoric in the seventeenth and eighteenth centuries by taking into account the logical calculi of Leibniz, Segner, Ploucquet, Holland and Lambert. These calculi give evidence of the tendency of logic to abandon the oral and aural dimension of rhetoric and to adopt, by analogy with algebra, the visual dimension of written signs. At the same time, the paper shows that some of these authors (Leibniz and Lambert in particular) wanted to establish a heuristic methodology as part of logic and, to this end, looked at the inventive techniques used in rhetoric, in particular topics, and at the inventive function of rhetorical figures, such as metaphor.