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NTU Philosophical Review

Issue 12, January 1989

Fu-Tseng Liu
Pages 283-312

The Need for a Possible World in the Tractatus Philosophy

Tractatus exponents have only occasionally used the expression 'possible world', and seem never to give prominence to the concept and theory of possible vvorld in the Tractatus philosophy. I here point out that the Tractatus philosophy not only intrinsically involves a possible world and has its own original and distinctive theory of possible world, but also that it at many points implicitly appeals to a possible world or somethings analogous-even though the expression 'possible world' never appears and the expression ‘imagined world' only appears once in the Tractatus text. First we show that the core of the theory of the structure of world in the Tractatus is itself a distinctive theory of possible world. Next we show that the following elements in the Tractatus conception appeal to possible world: the theory of the meaning of a proposition, the sense of a picture and the truth theory in the picture theory, the truth theory of propositions, and the concepts of tautology and contradiction. This is because, without appealing to a possible world, there could not be any false proposition, not could the definition of the falsehood of pictures and propositions be sustained. Moreover, the Tractatus semantics of tautology and contradiction depends completely on the concept of a possible world. Wittgenstein should be the first major discoverer of a possible world conception since Leibniz.

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