Document Type : Research

Author

• Asadollah Fallahi

Iranian Institute of Philosophy

Abstract

Aristotle defined a proposition as to be either true or false (ṣādiq aw kāẓib). But Avicenna, who mentioned the Aristotelian definition in all his books, except in his latest book, Pointers and Reminders, deviated from Aristotle’s and defined a proposition according to the truthfulness and lying of his “utterer.” (The compoisition which yields an assertion and which is one whose utterer is called “truthful” in what he says, or “a liar”). (Avicenna 1984, Inati’s translation, p. 77, ll. 222-223). This means that “ṣādiq” and “kāẓib” are the description of the utterer and not of the propostion itself, and this is contrary to the definition of Aristotle and of Avicenna himself in all previous works, which consider “ṣādiq” and “kāẓib” to be the description of the utterer and not the propostion. Some contemporaries have proposed reasons for Avicenna's shift from the first definition to the second one, and while reporting them, I show that the attribution of none of them to Avicenna is documented. On the contrary, I present a new reason that the probability of referring to Avicenna is not less, if not more, and that is that the words “ṣādiq” and “kāẓib” in ancient Arabic (before the Graeco-Arabic translation movement) did not mean what “true” and “false” and their equivalents mean in English and other languages, but that they meant “truthful” and “liar” and their equivalents mean in English and other languages.

Keywords

• true
• false
• truthful
• liar
• proposition
• utterer

Main Subjects

• Traditional Logic