So far, I explained to myself that the sentences starting with On... like this one:

On ne sait jamais.

can be viewed like starting with One... in English.

One never knows. One has to do something. One never forgets. etc.

But I also came across the use of Il faut... with the verb falloir, which to my understanding serves a similar purpose. Like the sentence from the well known song:

Il faut oublier.

Can this sentence be also translated: One has to forget? Does this construction with Il faut... has the same meaning as the constructions with On...?

And, most importantly, when to use each?

  • 2
    Dur dur. Lorsque quelqu'un pose une telle question, on ne sait pas ce qu'il faut répondre… Comment dire… Il faut d'abord qu'on comprenne l'origine du problème… ;-) Nov 3, 2016 at 23:24

1 Answer 1


On ne sait jamais.

This is more like "you never know", and "on" refers to the generalised/indefinite you, as opposed to a specific you, "tu/vous".

Il faut oublier.

The impersonal "il faut" is used neutrally when the idea of "who does something" does not particularly matter, or when it is obvious. It can be "we/you/I need to forget", depending on context.

If you need to specify the who, on the other hand, it can take the form of "il nous/me faut oublier" or "Il faut que je/tu oublie/oublies".

In my experience: As overwhelming as it may seem at first, it will all start falling into place without the need to dwell on the minutiae and to translate them into English as you come across a variety of sentences with these expressions.

  • 1
    Good answer, I'll add two things: 1) in some cases, you can use "tu" in French too as in "you never know", instead of "on", but it's less formal ; 2) "il faut" uses an impersonal form of the pronoun "il", the same as in "il pleut", "il est important de bien manger", "quelle heure est-il ?", so it's basically an "it"/"there" and can be replaced sometimes by "ce"/"ça".
    – Destal
    Nov 4, 2016 at 8:33

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