Sometimes the French use nous (we) to designate one person,
instead of je (the pronoun I). This practice is known as
nous de majesté, nous de modestie or
nounoiement. These names (majesty and modesty) have almost
opposite meanings because the singular nous can be used in very
different ways :
- when you represent the authority. The kings of France used it, hence
the sentence nous de majesté. Officials still use it in decrees:
"nous, maire de Paris, décidons de fournir des appartements
pas cher à nos enfants..."
- when you write a book or an article, and you want to say something
about you without being too personal. To express a personal belief, you
may say: "nous croyons fermement que les résultats macro-économiques
de la Politique Agricole Commune, etc". You will use "nous" in an academic
thesis, in a newspaper editorial, but certainly not in a Usenet post
or an Everything2 writeup.
In short, usage of nous de majesté is very restricted, and most
people have never used it in their life. A foreigner should really not
bother studying it.
The grammatical problem described in tu versus vous also arises with
nous: if there is an adjective, it should remain singular. Therefore the
following clause is correct although it may look strange even to
French eyes: "Nous sommes persuadé (or persuadée if a woman is speaking) de
la validité de notre point de vue".
Remember: if it's simple, it's not French.
Nounoiement was used by the Roman Emperors to give more authority to
their decisions. The first Emperor who said nos was Gallienus III.