Logical Studies

Abstract We in this article beside of explaining Quine’s most well-known criticisms of modal logic, try to show that Quine’s rejection of modal logic, and his opposition with essentialism, which he maintains that results from modal logic, could be founded on his epistemology and his treatment of objects. Meanwhile, we have mentioned Kripke’s point of view, as one of the most important defenders of modal logic. We are to show that Quine’s rejection of modal logic could be realized better if we consider it as opposing to Kripke’s ideas.

Abstract In this paper I first explain the fuzzy system and its roots in language speakers’ intuition, as claimed by its champions. I then introduce a quasi-formal interpretation of the standard logical system of fuzzy. After that I criticize the theory in two ways: first, I argue that its proponent's responses to the problem of Exact Truth-values are irrelevant or insufficient. Second, I show the theory does not have a uniform solution to the Sorites Paradox; especially the psychological parts of proposed solutions are not persuasive.

Abstract In 1970, Gödel showed his ontological argument to Dana Scott and discussed it with him. Afterwards, Scott presented a slightly different version of the argument at Princeton University. The logical system of the argument is a second-order quantified S5-modal logic with identity and an abstraction operator. Granted the acceptability of the underlying logical system, Gödel’s conclusion that necessarily there exists a God-like being ) ) can be derived from the premises-with Gödel and Scott on the scene, who can say otherwise? Sobel, however, proved that the system faces modal collapse-i.e. P↔□P is derivable from the system. Responding to Sobel, Anderson tried to block this by weakening some axioms and definitions.
In this paper, I will be trying to consider Gödel’s ontological argument (Scott’s version) from a logical point of view, along with Sobel’s criticism and Anderson’s emendations.

Abstract In this paper, after criticizing Sadra’s solution which is the distinction between Primitive and Common Predications, we will suggest a new solution based on analyzing the concept of ‘informing’ and show that ‘our inability of informing from absolute unknown’ is a feature of our cognitive state, not absolute unknown itself.

Abstract Quine's theory of meaning can be studied through several aspects. This article concentrates on one of the most important ones, i.e. ''Indeterminacy of translation''. In the thesis, several sides of Quine's philosophy are combined, so that studying and interpreting it seem to be a difficult task. ''Indeterminacy of translation'' says that there is no fact of the matter to choose between two or more inconsistent translation manuals that each of them conforms to all of the native's behavioral criteria. After illustrating the asymmetry between ''indeterminacy of translation'' and ''under-determination of theory of nature'', we can conclude that the certain content of ''Indeterminacy of translation'' is an ontological claim about meaning. Therefore, at first, Quine's understanding of meaning, his preferred ontology, and the relation between these two, must be explained and described, and then the asymmetry between these two theses can be discussed. An attitude toward these subjects from this point of view, not only is perceived an original apprehension of theory of meaning, but also can originate a new method in order to study abstract objects, propositional attitudes and mental states.

Abstract This essay studies Nisab Arba` or the relationships between universal concepts from historical aspect. The great pre-Avicennian logicians as like as Aristotle and Farabi, and also Avicenna himself didn’t pay attention to the issue of the four relationships between universal concepts with respect to their extensionality and comparability. Ghazali was the first philosopher who raised the above issue with intellectual restriction, without contrast relation. Afzal al-din khunaji and siraj al-din Urmawi–following him– were the first post-Ghazali logicians that explained the four relationships in the current forms, and the relations between their contraries.