Zur Zeit des Hl. Thomas von Aquin war es nicht leicht andere Religionen zu verstehen. Besonders auch deswegen nicht, weil die Verbreitung der Religion mit Macht und Krieg verbunden war. Aber gerade Thomas hat die sogenannte „Heidnische Lehre“ des Aristoteles in das Christentum eingeführt. In den Augen vieler orthodoxen Christen war dies ein unverzeihlicher Fehler. Mit dieser Lehre ist auch das Naturrecht (moralisch natürliche Gesetz) in die katholische Theologie eingeführt worden. Aber die Aristotelische Wiedereinführung (wenn nicht Revolution) in die christliche Philosophie ist bis heute nicht ohne Hindernisse geschehen. Chesterton meint, dass Thomas korrigiert Platon mit Aristoteles, der die Dinge so genommen hat, wie er sie vorgefunden hat. Thomas nimmt die Dinge so, wie sie Gott geschaff en hat. Trotz allem ist es sehr wertvoll zu denken, dass die Wahrheit und der Glaube nicht im Widerspruch stehen können, und alles was die Wissenschaft ans Licht der Welt bringt, kann nicht im Widerspruch gegenüber dem Glauben sein. In den Werken des Hl. Thomas ist immer die Welt der positiven Schöpfung gegenwärtig. In dieser Arbeit möchten wir die Bedingungen der Zeit des Dialogs mit dem Islam und dem Judentum als Hintergrund für die Zusammenfassung der Summa contra Gentiles analysieren nach den Gedanken von M.-D. Chenu, O. H. Pesch, J. Weisheipl, K. G. Chesterton und anderen, die uns ein Bild über die nicht einfache aber trotzdem erreichbare Begegnung mit anderen Religionen zeigen und auch die Gefahr aufzeigen, die sich in einer nicht konsequenten Philosophie birgt.

This paper attempts to show that if we carefully distinguish between the biological and metaphysical assumptions of Thomas Aquinas, it is possible, with the help of contemporary systems biology, to find good reasons for the thesis that the animation of a human individual takes place at conception. Systems biology is able to identify crucial events on the molecular level. The same would hold also for the possible human clone. In the paper I try to show that it is possible to maintain the notion of simultaneous animation along with the metaphysical assumptions of Thomas Aquinas, despite the fact that Thomas Aquinas himself advocated successive animation, due to his biological knowledge and the common opinions held in his times.

In this essay, an attempt is made to formalize the idea of analogy in a way which is as faithful as possible to Thomas Aquinas’ theory of analogy. To accomplish this, we must first present Aquinas’ theory of analogy as it appears in his main works; we then express the contents of Aquinas’ theory of analogy using Leśniewski’s Ontology, a symbolic language which is both rigorous and true to the spirit of Aquinas’ philosophy. In doing this we present definitions and theorems lying outside the scope of Leśniewski’s Elementary Ontology and we demostrate that the notion of “to be the definition of” is not an extensional functor.

Aristotle’s subtle distinction between the forms of friendship and his concept of loving friend as one’s other self propose a solution to the fundamental objection to any eudaimonian theory of slavery, namely that friendship – as basically non-moral phenomenon – is but an egoistic device of one’s happy life. Aristotelian theorems are based on his concept of analogy and on a philosophically specific notion of “self”. Since both of these are rooted in Platonism, Aristotle has toevolve them dialectically in a critical distance to Plato. Still, his dialectical theory of friendship needs to be rooted not in metaphysics but in political theory after all. Political friendship as a utopian perspective taken by each of the citizens in their pursuit of a close relationship with any other indicates a notion of “infinity as perfection” which presents the decisive step beyond Plato and toward the later course of the history of philosophy.

Modern philosophy of mathematics has been dominated by Platonism and nominalism, to the neglect of the Aristotelian realist option. Aristotelianism holds that mathematics studies certain real properties of the world – mathematics is neither about a disembodied world of “abstract objects”, as Platonism holds, nor it is merely a language of science, as nominalism holds. Aristotle’s theory that mathematics is the “science of quantity” is a good account of at least elementarymathematics: the ratio of two heights, for example, is a perceivable and measurable real relation between properties of physical things, a relation that can be shared by the ratio of two weights or two time intervals. Ratios are an example of continuous quantity; discrete quantities, such as whole numbers, are also realised as relations between a heap and a unit-making universal. For example, the relation between foliage and being-a-leaf is the number of leaves on a tree,a relation that may equal the relation between a heap of shoes and being-a-shoe. Modern higher mathematics, however, deals with some real properties that are not naturally seen as quantity, so that the “science of quantity” theory of mathematics needs supplementation. Symmetry, topology and similar structural properties are studied by mathematics, but are about pattern, structure or arrangement rather than quantity.

The present paper deals with the notion of essence in Thomas Aquinas. Part 1 focuses on the main points of Aquinas’s doctrine of essence set out in his De ente et essentia, and especially on the concept of essence as the “form of the whole” and the concept of the “nature considered absolutely”. The comparison with the teaching of Aristotle and Aquinas’s Arabic predecessors in Part 2 shows that Thomas’s notion of essence is an innovative re-interpretation, which he largely owes to Avicenna, of the original Peripatetic doctrine. Nevertheless, it is shown that this re-interpretation is to be understood as a result of Avicenna’s and Aquinas’s effort to provide a consistent explanation of various statements in Aristotle’s writings, not always compatible with each other.

In this paper I examine Aquinas’s commentary on a text of Aristotle in which the type of order between substance and accidents is discussed. I claim that Aquinas maintains that there cannot be any reference to sensibility, despite any prima facie interpretation of Aristotle’s texts, according to which it could be thought that substance is temporally prior to accidents and, hence, that we must presuppose a perceivable change in the world on the basis of which it is possible to consider something temporally prior to something else. This interpretation – which is possible on the basis of Aristotle’s texts – would be a misinterpretation, according to Aquinas. Aquinas’s assumption is philosophically worthwhile because it confi rms that every metaphysical proposition must abstract from sensibility.

John Mair (1467–1550) was an influential post-medieval scholar. This paper focuses on his Tractatus insolubilium, in which he proposed semantic analysis of self-referential phenomena, in particular on his solution to alethic and correspondence paradoxes and his treatment of their general semantic aspects as well as particular applications. His solution to paradoxes is based on the so-called “network evaluation”, i.e. on a semantics which defines the concepts of truth and correspondence with reality in contextual terms. Consequently, the relation between semantic valuation, synonymy and contradiction must be redefined.