The demonstrative aims of the Art explain some of the changes that Llull progressively introduced in its successive versions. In this sense, the change in title given to the Art from the time of its first version (Ars compendiosa inveniendi veritatem) to that of its second version (Art demostrativa), is significant. The Art demostrativa seems to reflect, even in its very title, Llull’s desire to present his epistemological device as a science which could be framed in terms set by the Aristotelian schema of the Posterior Analytics, the work of Aristotle which, according to the scholastic tradition, dealt with ‘demonstration’, with ‘necessary reasons’ that is, as opposed to the ars inventiva or Dialectic, which dealt with ‘probable reasons’. This desire seems even more clear when one considers this new title of the Art in tandem with another of the innovations offered by the Art demostrativa with respect to the Ars compendiosa inveniendi veritatem: namely, Llull’s claim that his Art operated, not by means of mere ‘signs’ alone, but by means of three types of demonstration, demonstration propter quid (by the cause), demonstration quia (by the effect) and demonstration per aequiparantiam (which, in his view, was the most demonstrative of all, being even more so than demonstration propter quid to which the scholastics, in accordance with Aristotle, reserved this privilege). Leaving aside this third type of demonstration, which Llull claimed to have discovered himself, the two other types situated the Art within the realm of the epistemological theorisations of the Posterior Analytics.

The Arts composed by Llull after the Art demostrativa never stepped outside this realm. On the contrary, in each of them, the Illuminated Doctor endeavoured progressively to extend his desire (already expressed in this work) to re-structure the traditional relations between inventio and demonstratio, with the aim of eradicating, in accordance with the directives regarding scientific knowledge stipulated in the Posterior Analytics, the demonstrative deficiencies inherent in Dialectic, while conserving, at the same time, the ‘inventive’ capacity which characterised this latter discipline and which he had mechanised by means of a combinatorial system. Paradoxically, this desire led Llull to create an Art which was simultaneously demonstrative (like the sciences described in the Posterior Analytics) and universal (like Dialectic) and which broke with the Aristotelian scientific model that only accepted particular demonstrative sciences. This break made Llull’s works an unavoidable reference point for all those thinkers who, like Descartes or Leibniz, wished, centuries later, to carry out similar enterprises.

Source: Josep Maria Ruiz Simon, “«Quomodo est haec ars inventiva?» (l’Art de Llull i la dialèctica escolàstica)”, Studia Lulliana, 33 (1993 [1995]), pp. 97-98.