Combining Texts

Ideas for 'On the Question of Absolute Undecidability', 'Tractatus Logico-Philosophicus' and 'W.V. Quine'

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6 ideas

12. Knowledge Sources / A. A Priori Knowledge / 2. Self-Evidence
If the truth doesn't follow from self-evidence, then self-evidence cannot justify a truth [Wittgenstein]
     Full Idea: If the truth of a proposition does not follow from the fact that it is self-evident to us, then its self-evidence in no way justifies our belief in its truth.
     From: Ludwig Wittgenstein (Tractatus Logico-Philosophicus [1921], 5.1363), quoted by Robin Jeshion - Frege's Notion of Self-Evidence 4
     A reaction: Frege seems to have taken self-evidence as intrinsic justification, but Wittgenstein seems to demand a supporting inference. But what is it all based on? Stipulative definitions?
12. Knowledge Sources / A. A Priori Knowledge / 5. A Priori Synthetic
The Tractatus aims to reveal the necessities, without appealing to synthetic a priori truths [Wittgenstein, by Morris,M]
     Full Idea: We can see the 'Tractatus' as an attempt to make sense of what is necessarily true of the world - in general, and not just in the mathematical case - without appealing to synthetic a priori truths.
     From: report of Ludwig Wittgenstein (Tractatus Logico-Philosophicus [1921]) by Michael Morris - Guidebook to Wittgenstein's Tractatus 2H
     A reaction: Morris sees the Tractatus as firmly in the Kantian tradition, and exploring Kant's main project in the first Critique.
There is no a priori order of things [Wittgenstein]
     Full Idea: Whatever we can describe at all could be other than it is. There is no a priori order of things.
     From: Ludwig Wittgenstein (Tractatus Logico-Philosophicus [1921], 5.634)
     A reaction: This is his rejection of Kant's dream, of inferring truths about the world by self-examination. However, compare Idea 23495. He clings to the faith that logic reveals 'something' about reality.
12. Knowledge Sources / A. A Priori Knowledge / 8. A Priori as Analytic
Logic and maths can't say anything about the world, since, as tautologies, they are consistent with all realities [Wittgenstein, by Grayling]
     Full Idea: Neither logical nor mathematical propositions say anything about the world, because in virtue of their always being true they are consistent with any way the world could happen to be.
     From: report of Ludwig Wittgenstein (Tractatus Logico-Philosophicus [1921]) by A.C. Grayling - Wittgenstein Ch.2
     A reaction: This became the standard view for twentieth century empiricists, and appeared to rule out a priori synthetic knowledge forever. Kripke's proposal that there are a posteriori necessities, however, changes the picture.
12. Knowledge Sources / A. A Priori Knowledge / 10. A Priori as Subjective
Logic is a priori because we cannot think illogically [Wittgenstein]
     Full Idea: That logic is a priori consists in the fact that we cannot think illogically.
     From: Ludwig Wittgenstein (Tractatus Logico-Philosophicus [1921], 5.4731), quoted by Robin Jeshion - Frege's Notion of Self-Evidence 4
     A reaction: A rather startling claim. Presumably we have to say that when we draw a stupid inference, then we weren't really 'thinking'?
12. Knowledge Sources / A. A Priori Knowledge / 11. Denying the A Priori
No pictures are true a priori [Wittgenstein]
     Full Idea: There are no pictures that are true a priori.
     From: Ludwig Wittgenstein (Tractatus Logico-Philosophicus [1921], 2.225)
     A reaction: This is part of the growing modern doubts about the scope or possibility of a priori knowledge. A 'picture' here is the mental model which is the meaning of a proposition.