Takashi Yagisawa

This paper aims to construct a logic of alternative-I that provides a proper conceptual framework for talk of possible-I in decision-making context, and thereby solves what we call the paradox of possible-I. The model of our logic, Alt-I model, is an adaptation of N. Belnap’s branching-time model, and the STIT (see to it that) operator defined on the model serves to represent choices and decisions made by actual and counterfactual agents. We conclude this paper by discussing the application of Alt-I model to the case of digital twins, digital copies of a person.

In my book, Worlds and Individuals, Possible and Otherwise , I use the novel idea of modal tense to respond to a number of arguments against modal realism. Peter van Inwagen’s million-carat-diamond objection is one of them. It targets the version of modal realism by David Lewis and exploits the fact that Lewis accepts absolutely unrestricted quantification. The crux of my response is to use modal tense to neutralize absolutely unrestricted quantification. Seahwa Kim says that even when equipped with modal tense, I am unsuccessful, given my view of reality and the proper use of modal tense in speaking of reality. I counter her attempt at resurrecting van Inwagen’s objection and clarify how we should use modal tense and how we should talk about reality

Meaning Solipsism says that it is possible for there to be a meaningful state without any other meaningful state. The meaning of such a solo meaningful state should be non-natural. The best strategy for establishing Meaning Solipsism is to argue for the determination of the meaning of a possible solo meaningful state via the set of entities the meaning of the state fits. Embracing merely possible and impossible entities is the most straightforward way to do so. Also, a good way to honor analayticities the meaning of a solo meaningful state gives rise to is to insist on certain facts about impossible entities as non-negotiable brute facts.

Call a sentential context semantically transparent if and only if all synonymous expressions are substitutable for one another in it salva veritate. Nathan Salmon has boldly advanced a refreshingly crisp semantic theory according to which belief contexts are semantically transparent. If he is right, belief contexts are much better behaved than widely suspected. Impressive as it is, this author does not believe that Salmon’s theory is completely satisfactory. This article tries to show that Salmon’s theory, in conjunction with a number of auxiliary but important claims he makes to buttress the theory, seems to lead to failure of semantic transparency of belief contexts.

Let us call a sentential context semantically transparent if and only if all synonymous expressions are substitutable for one another in it salva veritate. A sentential context is semantically opaque if and only if it is not semantically transparent. Nathan Salmon has boldly advanced a refreshingly crisp theory according to which belief contexts are semantically transparent.1 If he is right, belief contexts are much better behaved than widely suspected.2 Impressive as it is, I do not believe that Salmon's theory is completely satisfactory. I shall not try to refute his theory, however. My aim is more modest. It is to show that his theory, in conjunction with a number of auxiliary but important claims he makes to buttress the theory, seems to lead to semantic opacity of belief contexts.

Meaning Solipsism says that it is possible for there to be a meaningful state without any other meaningful state. The meaning of such a solo meaningful state should be non-natural. The best strategy for establishing Meaning Solipsism is to argue for the determination of the meaning of a possible solo meaningful state via the set of entities the meaning of the state fits. Embracing merely possible and impossible entities is the most straightforward way to do so. Also, a good way to honor analayticities the meaning of a solo meaningful state gives rise to is to insist on certain facts about impossible entities as non-negotiable brute facts

Meaning Solipsism says that it is possible for there to be a meaningful state without any other meaningful state. The meaning of such a solo meaningful state should be non-natural. The best strategy for establishing Meaning Solipsism is to argue for the determination of the meaning of a possible solo meaningful state via the set of entities the meaning of the state fits. Embracing merely possible and impossible entities is the most straightforward way to do so. Also, a good way to honor analayticities the meaning of a solo meaningful state gives rise to is to insist on certain facts about impossible entities as non-negotiable brute facts.

Deep theorizing about possibility requires theorizing about possible objects. One popular approach regards the notion of a possible object as intertwined with the notion of a possible world. There are two widely discussed types of theory concerning the nature of possible worlds: actualist representationism and possibilist realism. They support two opposing views about possible objects. Examination of the ways in which they do so reveals difficulties on both sides. There is another popular approach, which has been influenced by the philosophy of Alexius Meinong. The Meinongian approach is relevant to theorizing about possible objects because it attempts to construct a general theory of objects other than ordinary concrete existing objects. Independently of the debate about the nature of possible worlds or about Meinongianism, it is not always as straightforward as it may at first appear to determine whether putative possible objects are indeed possible. Another category of object similar to that of a possible object is the category of a fictional object. Although initially attractive, the idea that fictional objects are possible objects should not be accepted blindly. An important instance of theoretical usefulness of possible objects is their central role in the validation of two controversial theorems of a simple quantified modal logic.

When I assertively utter the sentence `Spot is a cat', the sentence I utter expresses a proposition. The truth condition of the proposition so expressed is determined by the semantic values of the singular term, `Spot', and the predicate, `is a cat'. If `Spot' refers to a certain particular entity E and `is a cat' expresses a certain particular property P, then the proposition in question is true if and only if E has P. Such is the theoretical cash value of reference. The referent of a given singular term generally figures in this manner in the truth condition of the proposition expressed by any sentence containing the singular term outside direct quotations and other referentially opaque contexts.1 Given this understanding of the notion of reference, I wish to address an important question: How is the reference of a proper name determined?

Those who object to David Lewis' modal realism express qualms about philosophical respectability of the Lewisian notion of a possible world and its correlate notion of an inhabitant of a possible world. The resulting impression is that these two notions either stand together or fall together. I argue that the Lewisian notion of a possible world is otiose even for a good Lewisian modal realist, and that one can carry out a good Lewisian semantics for modal discourse without Lewisian possible worls. I do so by generalizing Lewis' own idea that restrictions on quantification come and go with the pragmatic wind and relativizing possible worlds as shifting domains of discourse. I then suggest a way to soften the infamous incredulous stare.

Modal Dimensionalism is a metaphysical theory about possible worlds that is naturally suggested by the often-noted parallelism between modal logic and tense logic. It says that the universe spreads out not only in spatiotemporal dimensions but also in a modal dimension. It regards worlds as nothing more or less than indices in the modal dimension in the way analogous to the way in which Temporal Dimensionalism regards temporal points and intervals as indices in the temporal dimension. Despite its naturalness and intuitive appeal. Modal Dimensionalism has been largely ignored while the debates between David Lewis and his critics have dominated the discourse on the nature of possible worlds. It is high time that we took Modal Dimensionalism seriously as a viable alternative

On the first day of the class for Introduction to Philosophy, your professor tells you that if you keep perfect attendance, complete every homework satisfactorily, participate in class discussion actively, and score 100% in every examination, you will certainly get an A+ for the course. You work hard and by the end of the semester, you think you have accomplished all these things. You are pleased. Why? Because you think as follows: “I have kept perfect attendance, completed every homework satisfactorily, participated in class discussion actively, and scored 100% in every exam. This means I get an A+ for the course because, as the professor said, if I keep perfect attendance, complete every homework satisfactorily, participate in class discussion actively, and score 100% in every exam, I get an A+ for the course.”.