11.9 Referring to something indefinite - celui / celle / ceux / celles
There are pronouns that refer to something unknown. Now we have two forms of this unknown.
1) The referred object / subject is unknown, but existent.
The one who has told you that is a liar.
2) The referred object / subject is unknonw and possibly inexistent. Whoever may say so, is a liar. Whatever he may say, it is not true.
In English we see,
the structure changes. The same patterns we find in French. Celui / celle / ceux / celles qui / que is used, when there is an existent (but possibly unknown) person referred to. A construction with qui que ce soit (whoever it may be) is always possible. The second pattern is a bit more complex as we will see shortly.