Abstract
In this paper, we will reconsider the history of dualistic idealism (i.e., the main stream of western philosophy: chiefly, Plato, Descartes, Kant, Wittgenstein, etc.) under the quantum mechanical worldview. Recall that quantum mechanics also has the aspect of being a scientifically complete form of dualistic idealism. Therefore, it is reasonable to expect that almost all unsolved problems of philosophy (i.e., dualistic idealism) can be clarified under the linguistic Copenhagen interpretation. In this paper, we will show that the expectation is completely realized.