Logical Studies

Abstract The main problem of this article is logical validity analysis. According to Field, the necessary condition for intertheoretic logical validity of an argument is normative restrictions on belief in the premises and conclusion of that argument. However, the traditional view is that lexically valid arguments are not logically valid, despite applying such restrictions on beliefs, and therefore the said condition cannot be considered sufficient for logical validity. A large part of this article is devoted to examining this traditional view. It is believed that the distinctive feature of logical arguments from arguments made in other scientific branches is the formality of logical arguments. In this article, we examine what the formality of logic means and show that the belief in the logical invalidity of lexical arguments can be something of a dogma. we show that the belief in the logical invalidity of such arguments is something of a dogma. In this case, the acceptance of normative restrictions on the belief in the premises and conclusion of an argument can be considered a necessary and sufficient condition for intertheoretical logical validity.

Abstract The definition of proof means "definitely coherent analogy" indicates that it is important that the secret of the rise and greatness of this art in the science of logic must be understood on the one hand in relation to its purpose with the purpose of developing logic and on the other hand in the secret of truth for the purpose of the art of proof in case of compliance The rules contained in it searched. In this article, with the analytical-argumentative method, the conclusion is reached that firstly, the science of "logic" was compiled with the purpose of summarizing the rules of avoiding errors in thinking, and the art of "argument" was included in this knowledge with the purpose of summarizing the rules of the method of acquiring error-free knowledge. and secondly, since the acquisition of "certainty" depends on the two principles of "thinking on the basis of reality" and "using the element of necessity in thinking" and the law of causality is the only law that provides these two principles, the importance of "proof" depends on the law "Causality" returns.

Abstract Moore’s paradox is a proposition that can be true if it is not stated, but if it is stated, makes a paradox. This paradox has been raised in two forms, omission and commission, and since it was raised, many articles have been written about it, among them the contributions of John Williams has been more than others, and the confrontation of his view with Hamid Vahid’s view on this issue has provided a good reflection of the conflict and the different opinions on it. Williams believes in two approaches: the epistemic approach and the conscious belief approach. According to the first approach, since uttering the Moorean proposition is unjustified, it requires epistemic defect, and according to the second approach, when it is uttered consciously, it makes a paradox. Hamid Vahid believes in the theory of incomplete interpretation approach, according to which the expression of Moore’s proposition defeats the principle of charity, which says that the speaker’s words should always be considered true, unless there is an evidence against it. In this article, the critique and counter-critique of these two contemporary philosophers about Moore’s Paradox is analyzed and examined.

Abstract Abstract: Kit Fine developed a logic for different concepts of ground: weak full ground, weak partial ground, strict full ground, and strict partial ground. He claimed that one can define all other concepts of ground in terms of weak full or strict full ground. Particularly, he claimed that weak and strict full ground are inter-definable. He proposed the definitions as follows: strict full ground is irreversible weak full and weak full ground is nothing but preservation of strict full ground. Here, I argue that this interdefinability claim has problems. I first discriminate between two non-equivalent criteria for interdefinability: that some appropriate biconditionals are theorems of certain formal systems and that there are two formal systems for the two concepts in each of which the logical behavior of the other concept can be manifested. Then, I argue that based on these interdefinability criteria at least one of Fine’s proposed definitions fails. The conclusion is disjunctive: either there are other unknown definitions for these two concepts of ground in terms of each other or these two concepts are primitive.

Abstract In this research, we firstly reconstruct the Aristotelian categorical syllogism using the concept of inclusion(=subset). Then, we prove the soundness of the equation “Aristotelian syllogism= Inclusion properties + Proof by contradiction + Existential import”.  The proof of this equation will be formed by reconstructing the Aristotelian syllogism. There is a consensus view among the old logicians in favor of the usage of existential import as an assumption. Also, the proof by contradiction is considered as a general logical principle. Consequently, it can be concluded that the inclusion and its properties are the core important elements of the Aristotelian categorical syllogism. In the end, after introducing the concept of complexity of syllogism based on the properties of inclusion, we point out the concepts of self-evidency and groundability and their relationship in the Aristotelian categorical syllogism setting. We clarify that the relation of being self-evident and groundability is not equality and the groundability is a more general concept with respect to being self-evident.

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Abstract R.M. Hare is the founder of moral prescriptivism school of thought in the twentieth century. The basis of this school is strongly connected to the actions of moral agents. In his first intellectual procedure, Hare expresses moral statements in the form of imperative sentences. According to him, as indicative statements have logical form, imperative sentences, also, get logicalized by the help of phrastic (descriptor) aspect, and as a result, they possess the principle of consistency (lack of contradiction), logical connectives, and inference. As such, by making moral sentences imperative, Hare’s prescriptivism school of thought eliminates shortcoming of the lack of practical aspect in morality in which naturalists and intuitionists were captive. On the other hand, by the logicalizing imperative sentences, he refuses unreasoned views of sentimentalists. . . . . . . . . . . . . . . . . . . . . .. . . . . .

Abstract In conditional propositions, it is said that these propositions are formed from the second combination of single elements. So, every conditional proposition is composed of at least two categorical propositions, which are considered as their components. According to the opinion of logicians, these components lose the property of being a proposition and to be news after entering conditional letters on their heads; and for this reason, they are no longer truth and falsity; because these two descriptions are essentials accident of being news. But the accuracy in the components of conditional propositions shows that these components, when they are considered as part of conditional propositions, still have the characteristic of being news and being attributed to truth and falsity and with this criterion and the way of relationship between them, the truth and falsity of conditional propositions are determined. This article, with the approach of propositional analysis, comes to the conclusion that the components of conditional propositions, have the description of truth and falsity and that's why there are still news and propositions.

Abstract The assumption of the unity of mind is the basic foundation for most kinds of epistemic logic, decision theories, and theories of rationality. According to this hypothesis, at any given time t, the two principles of consistency and closure govern the set of beliefs of each person. On the other hand, both at the level of daily life and some kinds of logic as well, these two principles are repeatedly violated. The doctrine of fragmented mind seeks to explain how the mind can reason, judge, and draw conclusions in many cases relying on the two principles while allowing the violation of consistency and closure in some other cases. In this article, after mentioning the motivations of people to accept the hypothesis of unity, the doctrine of fragmented mind is introduced and clarified, and then it is explained how this doctrine can solve the problems of inconsistency and closure for one of the most important theories of content, namely the theory possible worlds. In the end, the doctrine of the fragmented mind is criticized on two levels. In the first level, it is shown that the doctrine of the fragmented mind is not a new idea and so it can be replaced by some known concepts in the epistemology of belief. In the second level, it is argued that some implausible consequences concerning the relationship between epistemology and philosophy of action result from the doctrine of the fragmented mind.

Abstract According to Priest’s Modal Meinongianism, every condition expressible in language, characterizes some object(s) satisfying the very condition, either in the actual world or in some other world(s). Similar commitments of other Meinongians, to such an unrestricted principle of characterization (CP), provokes the emergence of the Clark paradox. We argue that the inter-world bleed of information within Priest’s system of logic may ground similar complications. We demonstrate how to secure the possibility of world-shift by employing internal resources of the noneist semantics. This results in triviality; far beyond contradiction. Priest has to put restrictions on the CP.
According to Priest’s Modal Meinongianism, every condition expressible in language, characterizes some object(s) satisfying the very condition, either in the actual world or in some other world(s). Similar commitments of other Meinongians, to such an unrestricted principle of characterization (CP), provokes the emergence of the Clark paradox. We argue that the inter-world bleed of information within Priest’s system of logic may ground similar complications. We demonstrate how to secure the possibility of world-shift by employing internal resources of the noneist semantics. This results in triviality; far beyond contradiction. Priest has to put restrictions on the CP.

Abstract Alfred Tarski is one of the principal founders of logical semantics. He founded representational approach in 30s and this approach is dominant in the logical semantics nowadays. But if we return to Tarski’s 20s works it seems in first glance there is no semantical approach in his 20s works. Current commentary of Tarski’s the 20s works is that he regarded logic with syntactical and proof theoretic approach in this periods. But one of Tarski’s commentators, Douglas Patterson, has showed in details that in Tarski’s the 20s works is seen a kind of semantical approach which can regard it as expressive approach. Tarski called this approach intuitionistic formalism, following his teacher Stanisław Leśniewski. In this article we are intend to address, according to Patterson’s interpretation, what is Tarski’s the expressive approach. we will attempt to establish two claims: (a) intuitionistic formalism, according to Tarski, is an approach about function of language not an articulated semantical theory in which the central concepts of expressive approach are defined and analyzed; (b) intuitionistic formalism has no conflict with representational approach about language and the former is present in background of Tarski’s works, even several years after establishment of representational approach by him.