# 5.143 explained — Tractatus Logico-Philosophicus

> Chapter companion for Tractatus Logico-Philosophicus by Ludwig Wittgenstein.

## What happens

Wittgenstein distinguishes contradiction and tautology as extreme cases of propositions: contradiction is the external limit shared by no two propositions, while tautology is the substanceless center shared by all propositions.

## Themes in this chapter

### Logic and Tautology

Tautology is described as the substanceless center shared by all propositions, highlighting its role in logical truth.

### Nonsense and Meaning

Contradiction and tautology are shown as limiting cases that lack factual content, bordering on nonsense.

## Character check-ins

### Mr. Wittgenstein

Author of the Tractatus; presents the logical distinction between contradiction and tautology.

## Key lines

> Contradiction is something shared by propositions, which no proposition has in common with another.

Contradiction is a property that belongs to propositions only when they are compared, but no single proposition contains it inherently.

_Clarifies the relational nature of contradiction._

> Tautology is that which is shared by all propositions, which have nothing in common with one another.

Tautology is the common logical form present in every proposition, even though propositions otherwise differ completely.

_Emphasizes tautology as a universal logical feature._

> Contradiction vanishes so to speak outside, tautology inside all propositions.

Contradiction is like an outer boundary that propositions cannot cross, while tautology is an empty core within each proposition.

_Metaphor for the spatial limits of logical space._

## Links

- HTML: https://www.betterreads.online/discover/tractatus_logico_philosophicus_se/chapters/5-143
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- All chapters: https://www.betterreads.online/discover/tractatus_logico_philosophicus_se/chapters