PROPOSITION

The parts of arguments are declarative sentences. For the purposes of logic, a declarative sentence makes an assertion.

• Examples:
  • My father mailed a present to his grandson.
  • My father mailed to his grandson a present.
  • A present was mailed by my father to his grandson.

The three declarative sentences above are three distinct sentences, each having a unique word order. However, roughly, all three express the same proposition. The proposition is the thought expressed by the declarative sentence.

• Proposition differ from:
  • questions: "Did you pass logic?"
  • commands: "Shut the window."
  • exclamations: "Holy cow Batman!"

Questions, commands, and exclamations are not propositions because they do not assert something that is either true or false. Only of propositions can one say that they are true or false. For example, it is true or false that my father mailed a present to his grandson. But it makes no sense to say it is true or false that holy cow Batman.