Changes

===Propositions===

===Propositions===

Classical logic is based on propositions. It is often said that a proposition is a sentence that asks whether the proposition is true or false. Indeed, a proposition in mathematics is usually either true or false, but this is obviously a little too vague to be a definition. It can be taken, at best, as a warning: if a sentence, expressed in common language, makes no sense to ask whether it is true or false, it will not be a proposition but something else.

La logique classique est basée sur des propositions. On dit souvent qu'une proposition est une phrase qui demande si la proposition est vraie ou fausse. En effet, une proposition en mathématiques est généralement soit vraie, soit fausse, mais c'est évidemment un peu trop vague pour être une définition.... It can be taken, at best, as a warning: if a sentence, expressed in common language, makes no sense to ask whether it is true or false, it will not be a proposition but something else.

It can be argued whether or not common language sentences are propositions as in many cases it is not often evident if a certain statement is true or false.  

It can be argued whether or not common language sentences are propositions as in many cases it is not often evident if a certain statement is true or false.