# 5.121 explained — Tractatus Logico-Philosophicus

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

## What happens

This proposition states that if the truth-grounds of q are contained within those of p, then p follows from q, establishing a fundamental relationship of logical consequence.

## Themes in this chapter

### Logic and Tautology

The containment of truth-grounds directly relates to the logical structure of propositions and the nature of logical consequence.

## Key lines

> The truth-grounds of q are contained in those of p ; p follows from q .

If every situation that makes q true also makes p true, then p is a logical consequence of q.

_This defines logical consequence in terms of truth-ground containment._

## Links

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