cases. In one of these cases the proposition is true for all the truth-
possibilities of the elementary propositions. We say that the truth-
conditions are tautological. In the second case the proposition is false
for all the truth-possibilities: the truth-conditions are contradictory .
In the first case we call the proposition a tautology; in the second, a
contradiction.


4.461 Propositions show what they say; tautologies and contradictions show
that they say nothing. A tautology has no truth-conditions, since it is
unconditionally true: and a contradiction is true on no condition.
Tautologies and contradictions lack sense. (Like a point from which two
arrows go out in opposite directions to one another.) (For example, I know
nothing about the weather when I know that it is either raining or not
raining.)


4.46211 Tautologies and contradictions are not, however, nonsensical. They
are part of the symbolism, much as '0' is part of the symbolism of
arithmetic.


4.462 Tautologies and contradictions are not pictures of reality. They do
not represent any possible situations. For the former admit all possible
situations, and latter none . In a tautology the conditions of agreement
with the world--the representational relations--cancel one another, so that
it does not stand in any representational relation to reality.


4.463 The truth-conditions of a proposition determine the range that it