Propositions

Eric Pacuit

Philosophy

University of Maryland

The statements or claims used in an argument
(the premises and conclusion) are called propositions.  

  • propositions can be true or false
  • propositions are expressed by declarative sentences

A sentence is declarative if it makes a statement, that is, if it asserts something.

When a sentence contains an indexical, the truth or falsity of the sentence depends on who is uttering the sentence

  • Amsterdam is in The Netherlands. 
  • Textbooks are free in all of my courses.
  • I have been in the Skinner Building before.  
  • My computer was stolen.  
  • The dog ate the steak yesterday. 
  • There is a cat in the teapot.
  • Hay un gato en la tetera.
  • Er is een kat in de theepot

Many sentences can express the same proposition.

  • I have taken logic before.
  • I took logic.
  • This is not the first time I have taken logic.

A single sentence can express many propositions.

  • We saw the man with the telescope.
  1. Using a telescope, we saw the man.
  2. We saw a man who had a  telescope.
  1. There was no student who solved exactly two problems.
  2. There were exactly two problems that no student solved.
  • No student solved exactly two problems.

Propositions

By Eric Pacuit

Propositions

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