aristotle's demonstrative logic

Demonstrative logic, the study of demonstration as opposed to persuasion, is the subject of Aristotle's two-volume Analytics. Many examples are geometrical. Demonstration produces knowledge (of the truth of propositions). Persuasion merely produces opinion. Aristotle presented a general truth-and-consequence conception of demonstration meant to apply to all demonstrations. According to him, a demonstration, which normally proves a conclusion not previously known to be true, is an extended argumentation beginning with premises known to be truths and containing a chain of reasoning showing by deductively evident steps that its conclusion is a consequence of its premises. In particular, a demonstration is a deduction whose premises are known to be true. Aristotle's general theory of demonstration required a prior general theory of deduction presented in the Prior Analytics. His general immediate-deduction-chaining conception of deduction was meant to apply to all deductions. According to him, any deduction that is not immediately evident is an extended argumentation that involves a chaining of intermediate immediately evident steps that shows its final conclusion to follow logically from its premises. To illustrate his general theory of deduction, he presented an ingeniously simple and mathematically precise special case traditionally known as the categorical syllogisti

On the Dramatic Stage in the Development of Kotarbiński's Pansomatism

As the author sees it, Tadeusz Kotarbiński's reism is an ontology with semantical ramifications. Contrary to Kazimierz Ajdukiewicz's view the reist is not commited to any particular categorially determined language; he has to use, and is at liberty to do so, the language of whoever happens to be his opponent always provide that it is a categorially determined language. Contrary to Ajdukiewicz's opinion, the positive ontological thesis of resim (i.e. the thesis that for all a and b, if a is a b, then a is bulky and lasting) is not a tautology; it is a denial of the thesis held by unicategorial Platonism. Contrary to Ajdukiewicz's insistence, the negative ontological thesis of reism (i.e. the thesis that there are no properties, there are no relations, there are no events, etc.) consists of propositions which, in the light of multicategorial idealization of ordinary language, are meaningful and syntactically well constructed. They deny equally meaningful and syntactically well constructed assertions of multicategorial Platonism