On Uncertainty of Mental Concepts: From the Viewpoint of Wittgenstein’s Philosophy of Psychology

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 di-mension 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.