Modal Logic's theorems and rules are valid in POSSIBLE WORLDS but Relevant Logic's theorems and rules are valid, respectively, in logical WORLDS and situations. Robert Meyer in 1974 removed this asymmetry between the theorems and the rules of Relevant Logic by establishing a logical system, whose theorems and rules are valid in all situations. Introducing a new kind of truth and falsity operators, the authors in this article sketch a logical system defined on the basis of Relevant Logic. Such a system can not only preserve symmetry, but also remove some inconsistency between Modern Classical Logic and Relevant Logic, because the latter, like the former, puts POSSIBLE WORLDS as a criterion for validity.

Fictionalism about a region of discourse can provisionally be characterized as the view that claims made within that discourse are not best seen as aiming at literal truth but are better regarded as a sort of ‘ fiction’ . As we will see, this first characterization of fictionalism is in several ways rough. But it is a useful point of departure. In this paper, a general introduction of fictionalism is, preliminarily, provided. Then we briefly consider Yablo’ s classification, along with his very own reading of it. After a quick review over the notion of “ POSSIBLE WORLDS” throughout the history of the idea, we will come to show that how ontological problems rise against the POSSIBLE WORLDS semantics in contemporary methodology of philosophy, and that how Yablo’ s version of fictionalism (i. e. figuralism) helps to solve those problems. As a reading of fictionalism, (Yablo’ s) figuralism can lead to answer various other questions about ontology, reference, truth, etc, questions that are related to specific propositions such as mathematical or modal ones.

The notion of "POSSIBLE WORLDS" apparently raised by Leibnitz for the first time, is recently put into account for the role it plays in the semantics of modal logic. The most significant theories on POSSIBLE WORLDS are categorized into two general types,i.e.actualism and possiblilism about each of which there are various versions. In this survey, the versions of D.Lewis and kripke on possiblilismm and those of R.Stalnaker, R.Chisolm, R.Adams, and A.Plantinga on actualism are examined and criticized.

In the third part of his magnificent work, On the Plurality of WORLDS, David Lewis strives to argue against what he takes to be three seemingly POSSIBLE versions of abstractionist accounts of POSSIBLE WORLDS. As always, Lewis’s critical assessments are much clear and highly sophisticated. However, there are some complications in his discussion of the third kind of abstractionism, that is, what he calls the magical ersatzism. In this paper, I will attempt to clarify and defend Lewis’s objections against this third kind of abstractionism. As I will argue, the core of Lewis’s arguments against magical abstractionism (ersatzism) recognizes a sort of theoretical and methodological deficiency in such theories. Magical abstractionism does not fulfil our expectations about a sufficient account of POSSIBLE WORLDS and modality. Unlike linguistic and pictorial abstractionism, magical abstractionism does not provide us with a clear and explanatorily sufficient account of how POSSIBLE WORLDS represent the possibilities that we are inclined to accept. Magical abstractionists have a wrong conception of what is a sufficient metaphysical theory about modality. A true metaphysical theory about POSSIBLE WORLDS must have something positive to say about the nature of the abstract entities that are going to play the metaphysical role of those POSSIBLE WORLDS.

At first glance, it seems that we can find similarities between the POSSIBLE WORLDS proposed by Lewis and the theory of parallel WORLDS in physics. Both of these theories point to the possibility of the existence of WORLDS other than the one we live in. After Everett's theory, physicists’ attention was drawn to the notions of the multiverse and parallel universes. Parallel WORLDS are one of the theories that scientists and researchers in the field of physics are interested in. David Lewis, relying on physicalism and modal realism, is one of the supporters of the theory of POSSIBLE WORLDS. In this paper, the foundations of the two theories are explained using the analytical-descriptive method, and then, using the comparative method, Lewis's POSSIBLE WORLDS theory and parallel WORLDS are scrutinized. Both theories accept the existence of other WORLDS. Lewis's theory has six main features: 1- the existence and reality of POSSIBLE WORLDS; 2- the absence of a causal relationship between POSSIBLE WORLDS; 3- the similarity of POSSIBLE WORLDS to our world and the difference in the content of POSSIBLE WORLDS; 4- the impossibility of reducing POSSIBLE WORLDS; 5- indexical reality; and 6- the space-time unity of branches in a world and incoherency in time-space relations among WORLDS. The results of this research show that if parallel universes are confirmed as a scientific fact, then the second, third, and sixth features of Lewis's theory may conflict with physical reality. If there is a contradiction due to the fundamental nature of these features, Lewis's theory of POSSIBLE WORLDS will suffer a lot.

The theory of POSSIBLE WORLDS presents a model for narrative semantics. This essay focuses on the use of POSSIBLE WORLDS’ theory in narrative semantics with interdisciplinary approach. Conception of narration based on POSSIBLE WORLDS’ perspective is the main purpose of this paper. Based on this perspective, plot is not only textual actual WORLDS which some events occur in it, but also include POSSIBLE WORLDS which without regarding them, narrative semantics will remain incomplete. Such perspective is derived of semantics of modal logic; therefore, for explanation of this perspective attention to modal logic is necessary. Contemporary semantic theories have three main branches: philosophical, formal and linguistic semantics. Linguistic semantics uses formal semantics as a semantic logic in order to make clear how the study of meaning is. In this essay it will be illustrated that logical semantics can be applied in narrative semantics. Consequently, if the readers include private WORLDS of characters or fictional minds’ WORLDS and various POSSIBLE WORLDS in their reading, they will get more complete and more profound conception in reading narrative text, because a fiction is considered as a complete modal system and the mental representations of characters is equal with the PWs of a modal system. Some of accomplishments got, through foreshadowing to meaning of narrative text on the basis of this model, are the redefinition of plot and conflict notion. In order to apply this model in a narrative text, the binary Wandering Island and Wandering Cameleer novels by Simin Daneshvar has been chosen.

Conditional sentence is a compound sentence consisting of two clauses: protasis and apodosis. The purpose of this paper is investigating the conditional sentences in contemporary Persian language based on the Declerck and Reed typology (2001). According to this semantic typology, POSSIBLE world of protasis is divided in to two factual and theoretical classes. Theoretical POSSIBLE world can be neutral or nonneutral and the nonneutral is divided in to four types: closed, open, tentative and counterfactual. In the present study, we try to examine these types with respect to the corpus of 286 conditional sentences extracted from ten contemporary story books and the frequency of occurrence of each one to be determined separately. The analysis of Persian conditional sentences shows that the Persian conditional construction is compatible with mentioned typology and open POSSIBLE world has the highest occurrence frequency, and the neutral, closed, factual, tentative and counterfactual POSSIBLE WORLDS respectively dedicated the highest frequency of the open POSSIBLE world. The higher frequency of occurrence of the open POSSIBLE world arises from the fact that in this POSSIBLE world a probabilistic situation is considered and there is no certainty about its occurrence and this interpretation is most consistent with the operation of the conditional construction. This study also shows that in addition to the common conditional conjunctions such as “ agar, be shartike, vaella, vagarna, . . . ” other conjunctions are also used as conditional conjunctions like: “ valo, farzan, hamin ke, be mojarade inke, vaghti, cheo… che, hala ke, ta, ke … . ” .