The rules of grammar tell us how to put words together, just as a
blueprint tells us how to assemble a building. A mastery of
grammar allows us to formulate a thought clearly, no matter how
complex or subtle it is, and to express the thought in a way that
allows other people to share and appreciate it.
The grammatical structure of a sentence affects the proposition
that this sentence conveys.
1. Two different grammatical structures can be equivalent, just
as two words can be synonymous.
Jane did better than Tom on the test.
Tom did worse than Jane on the test.
Logically, these two propositions are equivalent; they assert the
2. A single sentence can assert more than a single proposition.
The statement "We live in a red house near the lake" contains the
We live in a house.
The house is red.
The house is near the lake.
Each of these is a proposition asserted by the sentence, and the
speaker is saying that each proposition is true.
3. A sentence does not always assert every proposition that it
The statement "The re-election of the president depends on whether
the economy improves by November" expesses, but does not
assert, the proposition that the economy will improve by November.
It is only saying that the president's re-election depends on
whether it turns out to be true.