Realtà, contraddizione, identità. La teoria delle opposizioni in Kant e Aristotele

The Thesis proposes the theoretical comparison of the positions of Kant and Aristotle on the concepts of “reality”, “contradiction” and “identity”. The analysis starts therefore from the respective formulations of the principle of (non) contradiction, of the notion and of the formula of identity, and of the oppositions between terms and statements that the first principle of thought makes possible. The aim of the Thesis is therefore to show, despite the temporal distance that separates the two philosophies, and despite the different and fundamental ‘speculative’ intentions of the two authors (which, too, we have tried to restore in their respective, intrinsic peculiarities), how Aristotle and Kant share a very similar basic epistemological position, that is, they provide an analogous, general determination of the cognitive relationship between thought and reality. Both, in fact – one by virtue of his own ‘metaphysical realism’, the other by reason instead of his first ‘metaphysical-empirical’ realism (‘pre-critical’ period) then instead ‘critical-transcendental’ (‘critical’ period) –, are concerned with contesting the sophisms and idealisms of their time, which in various ways and from different theoretical angles had tried to invert the “non-reciprocally convertible” relationship of actuality and power of the determinations of being or, more simply, of existence and essence of entities and substances. In Kant, above all, the maintenance of the correct relationship between the first formal principles and the first material principles of knowledge (1755-1768) or between intuitions and concepts (starting from 1770), is in fact achieved (also and above all) through the substantial reproposition of the Aristotelian theory of oppositions between terms and propositions, which the “Moses of the German Nation” uses to order in the correct categorical determination the simply logical opposition between concepts and propositions (analytical opposition or logical contradiction), the real opposition between truly existing forces (opposition between contrary terms and yet effective and real, and therefore perceptible) and the dialectical opposition of thesis and antithesis (opposition between contrary propositions, only apparently opposed as contradictory). Furthermore, as in Aristotle, the theory of the “conflict of realities” is earned by Kant through the polemical comparison with the major and most important physical theories of his time. Whereas in Aristotle the relationship between contrary terms – against the positions of Parmenides, Melissus of Samo, Anaxagoras, Empedocles, Plato, and the Platonists – is the one from which the properly physical phenomenon of movement arises, in Kant the concept of “real opposition” is definitively fixed by means of the fourfold critique of the geometric-mathematical conception of Cartesian space, Newton’s theory of “change of place”, Leibniz’s ‘epiphenomenal’ dynamics and the “conceptualist” definition of the contradictory conflict of Lambert’s realities. The Thesis is divided into three parts. The first, dedicated to the philosophy of Aristotle, is divided into two chapters. The first chapter analyzes the different formulations of the principle of non-contradiction, procured by Stagirite in his work: one ontological, the second logical, and the third psychological. The ontological formulation, preeminent with respect to the others, is in turn examined in its three different variants, of which the first abstracts from both the conditions of simultaneous time and sameness of point of view, the second from that of the same respect, while the third instead represents the complete and canonical one. In the central part of the chapter, the metaphysical relationship of belonging implied by the first principle of metaphysics and its logical-conditional value with regard to cognitive contents are then established. The indemonstrable character of the principle of non-contradiction is then equally determined, its legal irrefutability surfacing only mediately, that is, from the two kinds of indirect demonstration that Aristotle considers possible, namely the elenctic refutation and the apagogic proof. Finally, at the end of the chapter, the conceptual relationships are established between the principle of non-contradiction – as mentioned, the first principle of metaphysics –, the principle of the excluded middle (estimated as its fundamental corollary), and the notion of identity, which in Aristotle it does not rise to a real formula or principle but vice versa represents a subordinate notion, which is in any case implied in all the variants of the principle of non-contradiction that the Stagyrite offers in his work, according to a growing qualitative display of its conceptual prerogatives. The second chapter instead deals with the Aristotelian oppositions between terms and between propositions. As for the former, the chapter first focuses on the dual, reciprocal, and complementary exposition of oppositions: from contradiction to relative terms and from correlatives to contradictories. Then, it determines in detail the peculiar characteristics of each kind of opposition: that is, from top to bottom, contradictory terms, possession and privation, contrary terms, and relative ones. As far as the opposition between propositions is concerned, the chapter establishes the prerogatives of each typology and the reciprocal relationships within the so-called “Aristotelian logical framework”, concluding with an equal and opposite summary, with respect to the expository order adopted, of the results obtained. The first chapter of the second part of the Thesis addresses instead ‘tetradically’ both the Porphyrian positions on the true, the identical, and individuals and the medieval disputes on the onto-logical priority between the principle of contradiction and the formula of identity and the involvement of the notion and of the formula of identity in the problem, typical of the Middle Ages, of the multiplication of essences in individuals both to the relationships that contradiction and identity entertained with the ideas in the intellect of God. It, therefore, deals with the positions that Porphyry in late antiquity and Augustine, Boethius, Bonaventure of Bagnoregio, Thomas Aquinas, Henry of Ghent, Duns Scotus, and William of Ockham in the Middle Ages had to take on these questions, in an attempt to obtain a first theoretical-historical mediation between the philosophies of Kant and Aristotle regarding the topics mentioned above. The second chapter instead focuses on modern philosophies which, starting from Cartesian speculation, grappled with the principle of contradiction, the formula of identity, the principle of the excluded middle, and the problem of individuation. In addition to Descartes’ positions, also analyzed for what concerns the demonstration of the existence of God (on the basis of the methodological rule of evidence), the chapter, therefore, reviews the Lockean critique of the innateness of the first principles of thought and the contextual physicalization (or desubstantialization) of individuals; Leibnizian gnoseology, founded on the principles of contradiction and sufficient reason; the foundation of Wolffian philosophia prima on the principle of contradiction and the ontological priority of possibility over reality asserted by Baumgarten’s Metaphysica. Finally, the third part of the Thesis deals with Kant’s philosophy. The first chapter provides an analytical investigation of the first two Sectiones of the Nova dilucidatio of 1755. It first tries to account for the historical-philosophical context in which Schrift fits (§ 1). Then he moves on to the ‘critique’ contained therein of the presumed logico-metaphysical priority of the principle of contradiction over the principle of identity, as supported by both Wolff and Baumgarten in their respective ontologies (§ 2). It then proceeds to show the Kantian determination of the primacy of the principium identitatis over the principium contradictionis, emphasizing at the same time how Kant himself begins to become theoretician of the prominence – now above all metaphysical (or not yet completely empirical) – of existence with regard to possibility (§ 3). He then goes on to underline the Kantian deduction of the possibility (of things) from the contingent existence of entities and, ultimately, from the necessary existence of God, rather than from the contradiction and logical impossibility of entities, as instead happens in the metaphysics of the contemporaries (§ 4). Finally, it considers Kant’s demonstration of the antecedently determining principle of reason, which he presents in terms of an anti-Cartesian reformulation of the traditional ontological argument (§ 5). The second chapter instead proposes an analysis of the first three Betrachtungen of the Beweisgrund of 1763. It then presents the comparison of the respective concepts of existence in Kant, Wolff, Baumgarten, and Crusius, underlining the accusation of intellectualism that Kant addresses to his philosophical opponents (§ 1), thereby reaffirming how it is the existence of objects that is the foundation of the intrinsic possibility of concepts and not the other way around (§ 2). Finally, Kant’s brief introduction to the concept of real opposition (§ 3) is considered, which is analyzed in more detail in the following chapter. In fact, the third chapter deals with the analysis of the Kantian positions of Versuch of 1763. In the first paragraph, the critique of the Wolffian matrix of mathematice philosophari is presented. In the second, the accusation of logicism against the rationalistic metaphysics of his time is explored, of which the concept of Realrepugnanz represents the keystone. Finally, the third paragraph of the chapter presents real opposition as a concept whose matrix is clearly Newtonian, as can already be seen from some considerations in the Physical Monadology of 1756. In the final chapter of the work, the positions of the ‘mature’ Kant are analyzed, expressed in the Kritik der reinen Vernunft and in the Metaphysische Anfangsgründe der Naturwissenschaft. The first paragraph considers the definition of the principle of contradiction, established in Pure Reason as the sufficient condition of analytic judgments and as the sine qua non (or simply necessary) condition of synthetic judgments a priori. The second paragraph instead deals with the notion of “identity” and the realer Widerstreit in the ‘almost-dialectical’ framework of the Amphibolia of the concepts of reflection. The third paragraph instead concerns the conflict between realities, as it is thematized and explored in the metaphysical principles of natural science, i.e. through the polemical comparison with some of the major physical-mathematical positions of Modernity, including those of Descartes, Leibniz, Newton, and Lambert. The fourth paragraph instead examines the dialectical opposition of the first two cosmological antinomies, established as an opposition between contrary and therefore only apparently contradictory propositions. Finally, the fifth deals with the apagogical proof, which Kant, unlike Aristotle, does not deem too useful for the epistemological purposes of transcendental philosophy, since it fails to make the cognitive foundations of the truth fully understandable, which it (only) logically succeeds in to demonstrate. Naturally, his conclusions complete the Thesis, which try to restore the results of the comparative analysis – theoretical and epistemological, even before historical – of the positions of Kant and Aristotle on the relative theories of reality, contradiction, identity, and oppositions between terms and propositions.