ISSN: 1308-6200 | Publisher: Kültür Ajans 

Karadeniz International Scientific Journal

This is an internationally refereed social science journal that is published every three months (quarterly) in electronic-based and print-based since 2009. The journal publishes four issues each year (March, June, September, and December).

The publication language of this journal is Turkish, English, or Russian.

This is an open-access journal. Therefore, all issues and articles published so far can be accessed free of charge from the journal's website.

 

Issue 40
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RULES PROPOSAL THAT DETERMINING VALIDITY OF EXISTENTIAL MOODS OF CATEGORICAL SYLLOGISMS BY VENN DIAGRAMS

Caner ÇİÇEKDAĞI

Some difficulties on formal logic arise in the validity control of syllogisms by Venn diagrams. While it is quite easy to understand and determine strong valid syllogisms by Venn diagrams, the difference between the weak valid conditions and invalid conditions cannot be easily understood. Although the formation of a categorical syllogism as weak valid is accepted to be true by Aristotle, it is called existential fallacy by Boole because such syllogisms which we can call “subalternate mood” reach a particular conclusion from two universals and, thus, reach a particular proposition with an existential import from universal propositions with no existential import and make an existential supposition. This of course will be the focus of another study because this study accepts from the beginning that existentially supposed syllogisms are valid and the presence of rules related to the validity while controlling with Venn diagrams is researched. In this study which can be considered to be very technical, it is aimed to guide academicians and educators as well. The basic problem is to find comprehensive rules related to the validity of syllogisms in weak or existential mood. The invalid moods of these syllogisms are studied by Venn diagrams. Specifically the fourth figure includes some problems due to the presence of syllogisms in existential mood and forms the focal point of this study. The basic method is to interpret the control and results by means of Venn diagrams. Through some informations which can be considered as introduction, it is aimed that the reader who is not familiar to logic can understand the problem easily. Then, thirty two existential moods belonging to the four figures of categorical syllogisms are analyses by Venn diagrams in order to present the problem. Since he main area of problem is how weak valid syllogisms and invalid syllogism are separated from each other, the suggestions about rules that can solve this problem are made in the present study.

Keywords: Venn diagram, weak validity, particular conclusion, existential mood, fourth figure, syllogism

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