In this paper, we discuss an uncertainty of mental concepts. In the application of mental concepts, we often face disagreement. For example, observing a behavior, some person judges he/she is sad, but others do not. Surprisingly, in his Last Writings on the Philosophy of Psychology, Wittgenstein says that there is an uncertainty of criteria in the mental concepts. In other words, he thinks disagreement in judgements about other’s mental state originates from conceptual dimension rather than empirical dimension. (e.g., differences in context and information quantity) The goal of our study is to clarify why mental concepts have this kind of uncertainty.

The ensemble interpretation (EI) of quantum mechanics has been proposed by physicists and philosophers (e.g., A. Einstein, K. R. Popper, and A. Lande). However, it is not accepted widely among modern scientists. This is because the EI is regarded as a kind of the hidden variable theories. The scientists believe that the EI is inconsistent with violation of Bell's inequalities. The present paper points out that there are various types of the EI. Several of them can be consistent with the violation. The non-local type of the EI proposed by Shirai in 1998 is also consistent. We call it “holistic ensemble interpretation (HEI).” The non-locality in the HEI includes a temporal non-locality (i.e., a future dependence), implying that the present distributions depend on the future conditions. The concept of the future dependence would be so controversial that we discuss it deeply in the latter half of the paper. Many scientists may think of it as a doubtful concept, because it disagrees with the concept of “free will.” However, there are several reasons why we should consider the future dependence.

In the process of presenting his theory of conversational implicature, Paul Grice (1975) segmented cases of conversational implicature into three groups: Group A, where no maxims are violated; Group B, where the violation of a maxim is to be explained by the supposition of a clash with another maxim; and Group C, which involves the exploitation of a maxim. Yukiko Kawaguchi, however, claimed in her 2001 article that this categorization is ill-grounded. This paper proposes, in opposition to Kawaguchi, an interpretation of Grice’s theory of conversational implicature which accords with his treatment of conversational implicature and provides reasonable evidence in support of his categorization of it.

This paper is about the status of compositionality in our linguistic communication and its theorizing. The principle of compositionality has been regarded as an essential precondition under which semantic theories are built since the principle seems to properly explain some important facts about natural language, such as learnability and novelty. According to recent discussions, however, the precise understanding of compositionality casts doubt on its necessity. In this paper, I take a closer look at how we have started and improved our semantic investigations, and present a new argument for compositionality which is based on our linguistic intuition about the notion of un-synonymy and substitution. My point of the argument is that compositionality can serve as a useful tool for theorizing natural language semantics even if semantic rules themselves are described non-compositionally.