Propositions and Sentences

A concept identifies a certain class of things; a proposition asserts something about that class. Concepts give us indispensable tools for thought and speech by grouping together similar objects, actions, properties, and relationships. However, a concept by itself is not a complete thought, and a word by itself doesn't say anything.

Words need to be put together into sentences that express propositions. One essential feature of a proposition is that it is either true or false.

To assert a proposition, we need a complete declarative sentence, with a subject and a predicate.

Example:
The following are propositions:

Jack is a Baptist.
Some birds fly south for the winter.
I would like a Jaguar XJ-S for Christmas.

The following are fragments:

Game
The Pillsbury Dough Boy
Ran too fast for me to catch him
Was two blocks south of the library


Comprehension Questions
1 One essential feature of a proposition is
a) It asks a question.
b) It is either true or false.
c) It issues a command.
2 Does the following express a proposition or a fragment?

While waiting for the bus to come.

a) Proposition
b) Fragment
3 Does the following express a proposition or a fragment?

While waiting for the bus to come, I read the newspaper.

a) Proposition
b) Fragment
4 Does the following express a proposition or a fragment?

The tallest building in the world.

a) Proposition
b) Fragment
5 Does the following express a proposition or a fragment?

The Sears Tower is the tallest building in the world.

a) Proposition
b) Fragment

Words in Propositions

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