Language/French/Grammar/L’on-VS-on

Use of l’on and on in French

We often find, instead of the pronoun on, the variant l’on. Where does this apostrophe come from and in what context should it be used?

You should know that our indefinite pronoun on, which often behaves like a real personal pronoun, is originally a common noun, of the same origin as the name man. The Latin name homo ("man, human being") and its accusative form hominem were transformed into on and man respectively in Old French. Note that a similar phenomenon has occurred in other languages: in German, the words Mann ("man") and man ("on") have a common origin.

The apostrophe L of on is not originally a euphonic consonant, but the definite article: L’ON was synonymous with humans in general. Over the centuries, this name has evolved into a true indefinite pronoun (denoting an undetermined individual) and its definite article has become optional. This development could be schematized with these three examples:

• L’homme est bien peu de chose.

Man is very little.

• L’on est bien peu de chose.

We are very little.

• On est bien peu de chose.

We are so little.

By the seventeenth century, the form on was no more than an optional variant of on. Today, this survival of the old French is maintained especially in contexts where it plays a euphonic role.

Here is what modern grammars recommend.

L’ON is better than ON

When it avoids a hiatus (sequence of two phonetic vowels)

The case arises in particular after these words: et, ou, où, qui, quoi, si.

• C’est un retour aux sources, si on veut. (It's a homecoming, if you will)

hiatus

• C’est un retour aux sources, si l’on veut.

better

After the word that, to avoid syllable “qu’on” which sounds bad.

• Il faut assumer ce qu’on dit (You have to take responsibility for what you say)

Qu’on: sounds bad

• Il faut assumer ce que l’on dit.

better

This recommendation is especially valid when this syllable is itself followed by a verb starting with co- or com-.

• Ce qu’on conçoit bien s’énonce clairement. (What is well understood is clearly stated.)

qu’on con  : sounds bad

• Ce que l’on conçoit bien s’énonce clairement.

Better

Conversely, L’ON is better than ON

When followed by a word starting with l, to avoid alliteration (repetition of the same consonant).

• On se cultive quand l’on lit beaucoup (We cultivate ourselves when we read a lot.)

l’on lit : alliteration

• On se cultive quand on lit beaucoup.

better

This remains true in cases with a hiatus. This hiatus is better than alliteration, though.

• C’est une famille où l’on lit beaucoup. (It's a family where you read a lot.)

l’on lit : alliteration

• C’est une famille où on lit beaucoup.

où on : hiatus, but better

After DONT. The sequence of which one (the t is pronounced by making the connection) is preferable to L’ON.

• C’est un roman dont l’on dit beaucoup de bien. (It’s a well-spoken novel.)

dont l’on : to avoid

• C’est un roman dont on dit beaucoup de bien.

better

These rules are more or less well respected and are by no means compulsory, but they are recommended in careful French.

Several authors use one in other contexts, contexts where euphony is not at issue, especially at the beginning of a sentence: L’on ne saurait mieux dire.. These uses, which are found especially in a sophisticated, literary or archaic style, may seem affected depending on the context. It is a matter of judgment and good taste.

Source

https://www.antidote.info/fr/blogue/enquetes/et-lon