Tractatus Logico-Philosophicus · Chapter
4.241 explained
Wittgenstein explains that using two signs with the same meaning is expressed by the sign '=', indicating replaceability.
What happens
Wittgenstein explains that using two signs with the same meaning is expressed by the sign '=', indicating replaceability. He also describes definitions as symbolic rules, referencing Russell's notation.
Themes in this chapter
Picture Theory of Language
The discussion of signs and replaceability relates to how language pictures reality through symbolic rules.
Characters to notice
- Bertrand Russell
Referenced for his use of the definition form 'a = b Def.'
Key passages
“If I use two signs with one and the same meaning, I express this by putting between them the sign “ = ”. “ a = b ” means then, that the sign “ a ” is replaceable by the sign “ b ”.”
When two signs have identical meanings, we use '=' to show that one can be substituted for the other.
Clarifies the role of identity in symbolic logic.
“A definition is a symbolic rule.”
A definition functions as a rule for manipulating symbols.
Emphasizes the formal nature of definitions.