4.023 A proposition must restrict reality to two alternatives: yes or no.
In order to do that, it must describe reality completely. A proposition is
a description of a state of affairs. Just as a description of an object
describes it by giving its external properties, so a proposition describes
reality by its internal properties. A proposition constructs a world with
the help of a logical scaffolding, so that one can actually see from the
proposition how everything stands logically if it is true. One can draw
inferences from a false proposition.


4.024 To understand a proposition means to know what is the case if it is
true. (One can understand it, therefore, without knowing whether it is
true.) It is understood by anyone who understands its constituents.


4.025 When translating one language into another, we do not proceed by
translating each proposition of the one into a proposition of the other,
but merely by translating the constituents of propositions. (And the
dictionary translates not only substantives, but also verbs, adjectives,
and conjunctions, etc.; and it treats them all in the same way.)


4.026 The meanings of simple signs (words) must be explained to us if we
are to understand them. With propositions, however, we make ourselves
understood.


4.027 It belongs to the essence of a proposition that it should be able to