A phrase that functions as a noun, either in the subject or the
predicate of a sentence, is called a noun clause.
Noun clauses can be either asserted or not asserted within a
Compare these two sentences:
1. The president knows that war is imminent.
2. The president believes that war is imminent.
In both cases we are making an assertion about the president.
In both cases we use a noun clause, "that war is imminent,"
to convey what it is that the president knows or believes. And in
both cases the noun clause expresses a proposition. The
difference is that sentence 1 asserts the proposition, whereas
sentence 2 does not.
The English language contains a large class of verbs that we use
to describe what people say and think. We can classify these
verbs on the basis of whether or not they imply the endorsement
of what is said or thought.
The following verbs do not assert what is said or thought: believes,
says, argues, is convinced, and suspects.
The following verbs do assert what is said or thought: knows,
acknowledges, proves, is aware, and realizes.
In the study of argument, it is crucial to know whether a speaker
is endorsing a given proposition as one of his or her own premises or
merely reporting that someone else accepts that proposition.