Aristotle axiomatically divides the 28 syllogisms of necessity of Anal, prior. I 9-11 into two classes: those with a necessary conclusion and those with a non-necessary conclusion. The fact that Aristotle axiomatically comprehends only 24 syllogisms of necessity, however, raises two questions: 1. What method does he use to decide about the remaining four syllogisms? 2. Is this method consistent with the initial one? This essay pursues the answers to these questions first by means of semantic analysis, showing that Aristotle (...) ultimately considers assertoric propositions to be possible and therewith non-necessary propositions. Aristotle employs this approach, developed within the axiomatic, to the four syllogisms in question, thereby integrating them into the axiomatic. Finally, this essay answers the question of consistency by way of a formalization of the syllogisms of necessity. (shrink)

Aristotle axiomatically divides the 28 syllogisms of necessity of Anal, prior. I 9-11 into two classes: those with a necessary conclusion and those with a non-necessary conclusion. The fact that Aristotle axiomatically comprehends only 24 syllogisms of necessity, however, raises two questions: 1. What method does he use to decide about the remaining four syllogisms? 2. Is this method consistent with the initial one? This essay pursues the answers to these questions first by means of semantic analysis, showing that Aristotle (...) ultimately considers assertoric propositions to be possible and therewith non-necessary propositions. Aristotle employs this approach, developed within the axiomatic, to the four syllogisms in question, thereby integrating them into the axiomatic. Finally, this essay answers the question of consistency by way of a formalization of the syllogisms of necessity. (shrink)

This study gives an arithmetic calculus to determine tautologies, contradictions and satisfiable formulas of the first order logic. The presented calculus may easily be extended on modal and deontic logic. The mathematical foundation of this arithmetic calculus is a Boolean ring.

Summary This study continues in calculating formulas of the first order logic. Whereas the preceding part delt with monadic predicates, the present part treats polyadic predicates. The presumptions were supplied analogously.

The goal of this paper is an interpretation of Aristotle's modal syllogistics closely oriented on the text using the resources of modern modal predicate logic. Modern predicate logic was successfully able to interpret Aristotle's assertoric syllogistics uniformly , that is, with one formula for universal premises. A corresponding uniform interpretation of modal syllogistics by means of modal predicate logic is not possible. This thesis does not imply that a uniform view is abandoned. However, it replaces the simple unity of the (...) assertoric by the complex unity of the modal. The complexity results from the fact that though one formula for universal premises is used as the basis, it must be moderated if the text requires . Aristotle introduces his modal syllogistics by expanding his assertoric syllogistics with an axiom that links two apodictic premises to yield a single apodictic sentence . He thus defines a regular modern modal logic. By means of the regular modal logic that is thus defined, he is able to reduce the purely apodictic syllogistics to assertoric syllogistics. However, he goes beyond this simple structure when he looks at complicated inferences. In order to be able to link not only premises of the same modality, but also premises with different modalities, he introduces a second axiom, the T-axiom, which infers from necessity to reality or - equivalently - from reality to possibility. Together, the two axioms, the axiom of regularity and the T-axiom, define a regular T-logic. It plays an important role in modern logic. In order to be able to account for modal syllogistics adequately as a whole, another modern axiom is also required, the so-called B-axiom. It is very difficult to decide whether Aristotle had the B-axiom. The two last named axioms are sufficient to achieve the required contextual moderation of the basic formula for universal propositions. (shrink)

On the unity of modal syllogistics in Aristotle. The goal of this paper is an interpretation of Aristotle’s modal syllogistics closely oriented on the text using the resources of modern modal predicate logic. Modern predicate logic was successfully able to interpret Aristotle’s assertoric syllogistics uniformly, that is, with one formula for universal premises. A corresponding uniform interpretation of modal syllogistics by means of modal predicate logic is not possible. This thesis does not imply that a uniform view is abandoned. However, (...) it replaces the simple unity of the assertoric by the complex unity of the modal. The complexity results from the fact that though one formula for universal premises is used as the basis, it must be moderated if the text requires.Aristotle introduces his modal syllogistics by expanding his assertoric syllogistics with an axiom that links two apodictic premises to yield a single apodictic sentence. He thus defines a regular modern modal logic. By means of the regular modal logic that is thus defined, he is able to reduce the purely apodictic syllogistics to assertoric syllogistics. However, he goes beyond this simple structure when he looks at complicated inferences.In order to be able to link not only premises of the same modality, but also premises with different modalities, he introduces a second axiom, the T-axiom, which infers from necessity to reality or – equivalently – from reality to possibility. Together, the two axioms, the axiom of regularity and the T-axiom, define a regular T-logic. It plays an important role in modern logic. In order to be able to account for modal syllogistics adequately as a whole, another modern axiom is also required, the so-called B-axiom. It is very difficult to decide whether Aristotle had the B-axiom. Each of the two last named axioms is sufficient to achieve the required contextual moderation of the basic formula for universal propositions. (shrink)