In the following exercises, the students were asked to if each sentence is a proposition or not, and then to explain their answers.  I have provided for you some sample answers and instructor's comments for each.

1. The batter hit the baseball 502 feet into the center field bleachers.

Adrian's answer:

This is a proposition. It is either true or false that the ball went 502 feet.

Instructors comments: Correct, good.

2. The teacher exclaimed, "Don't come into class late again!"

Adrian's answer:

This is not a proposition, it is a command and an exclamation.

Instructor's comment:

This is a proposition. It is either true or false that the teacher made the statement.

3. Blue is my favorite color.

Adrian's answer:

This is not a proposition, it is just an opinion.

Instructor comments: Be careful about what you say is just an opinion. Can it be true or false that the person's favorite color is blue? I think so. It may be that we have no other means of checking the truth of the proposition than by person's own word, and, for all I know, the person could be lying about their favorite color. None of those considerations change the fact that the statement is either true or false.

4. Scientists have discovered the remains of a lost civilization on the floor of the Atlantic Ocean.

Adrian's answer:

This is not a proposition, because I know it is not true.

Instructor's comments: This is a proposition. It's a false  proposition (as far as I know). A sentence does not have to be true to be a proposition.

5. Wow! Did you see that baseball sail out of the park?

Adrian's answer: This is not a proposition. It is an exclamation and a question

Instructor's comment: Correct, good.

6. The Fuehrer is independent of all groups, associations, and interests, but is bound by laws which are inherent in the nature of the people.

Adrian's comment: I don't know what this means, so it is difficult to say if it can be true or false.

Instructor's comments: Very good. Sometimes sentences can be so fuzzy and confusing that the best response is to admit that you can't make a judgment about it.

7. I now pronounce you man and wife.

Karla: I don't know, it sounds like a command.

Instructor's comments: This is not a proposition, but is a very special kind of sentence. It is like blessing or a toast, it is designed to help establish, and confirm a specific reality.  Specific individuals are granted certain authority to confer specific titles, rights, and responsibilities on others.  For example, when you graduate, the Chancellor, by the authority given to him by the UNC system and the government of North Carolina, will confer upon you your degree with "all the rights and responsibilities appertaining there unto."  (Please note that philosophers have disputed frequently about sentences such as this.

Are you ready to complete an exercise on your own?  If so, click here.