# 6.23 explained — Tractatus Logico-Philosophicus

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

## What happens

Wittgenstein discusses the meaning of the equality sign, stating that it indicates substitutability between expressions, and that this substitutability must be evident from the logical form of the expressions themselves.

## Themes in this chapter

### Logic and Tautology

The equality sign and substitutability are treated as logical features inherent to the expressions.

## Character check-ins

### Mr. Wittgenstein

Author of the proposition

## Key lines

> If two expressions are connected by the sign of equality, this means that they can be substituted for one another. But whether this is the case must show itself in the two expressions themselves. It characterizes the logical form of two expressions, that they can be substituted for one another.

The equality sign indicates that two expressions are interchangeable, but this interchangeability must be evident from the expressions themselves, revealing their logical form.

_Clarifies the role of equality as a marker of logical form._

## Links

- HTML: https://www.betterreads.online/discover/tractatus_logico_philosophicus_se/chapters/6-23
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