This article is from the Atheism FAQ, by mathew email@example.com with numerous contributions by others.
The building blocks of a logical argument are propositions, also
called statements. A proposition is a statement which is either true
or false. For example:
"The first programmable computer was built in Cambridge."
"Dogs cannot see colour."
"Berlin is the capital of Germany."
Propositions may be either asserted (said to be true) or denied (said
to be false).
Note: This is a technical meaning of the word "deny", not the everyday
When a proposition has been asserted based on some argument, we
usually say that it has been affirmed.
The proposition is generally viewed as the meaning of the statement,
and not the particular arrangement of words used. So "An even prime
number greater than two exists" and "There exists an even prime number
greater than two" both express the same (false) proposition.
Sometimes, however, it is better to consider the wording of the
proposition as significant, and use linguistic rules to derive
equivalent statements if necessary.