Learning French: when and why do we say enfoncer une porte ouverte?

Have you ever tried teaching the sun to shine? Said that rain is wet? If so, you might have been met with the phrase: tu enfonces une porte ouverte. 

This casual 18th Century expression points out a futile action or statement.

We will look at how to use this phrase in everyday French so you can sound like a native in no time. 

What does enfoncer une porte ouverte mean?

Enfoncer une porte ouverte literally translates as: to break down an open door.

Do not panic - this popular phrase is not encouraging forced entry or trespassing. It is actually used when someone explains something evident, does something useless, or puts effort into a problem which has already been solved. 

In English, the closest expressions are:

• To state the obvious 

• Thanks Captain Obvious!

Related expressions include:

• Dire une évidence - To state the obvious

• Porter de l’eau à la rivière - To beat a dead horse (literal translation: to bring water to a river)

• Prêcher des convaincus - To preach to the choir

• Enseigner à un poisson à nager - To teach a fish to swim

Read also: Understanding 'dis donc': the versatile French expression

What are the origins of enfoncer une porte ouverte?

The visual nature of this metaphor makes it easy to understand. 

Some historians argue it comes from the time of knights and castles, around the end of the 18th Century, when attacking armies broke down castle doors to claim a kingdom.

However, if the defenders left the doors open then there would be no resistance, making the attack useless or at least suggesting an obvious win. 

Hence today’s interpretation of the phrase: just as there is nothing glorious about attacking an open door, it is pointless to say or do something which has already been covered.

Read also: Understanding 'les doigts dans le nez': origins and usage of a quirky French expression

When do you say enfoncer une porte ouverte?

It is often used to mock someone or bring humour to a conversation. Depending on your tone of voice, this phrase can be delivered as an affectionate tease or a sarcastic dig. 

You can say enfoncer une porte ouverte in response to an obvious statement: 

• Statement: Je suis sorti sous la pluie et je suis revenu trempé. - I went out in the rain and came back soaked.

• Response: Tu enfonces une porte ouverte. - What did you expect?

It can be used to refer to a futile action or argument:

• Expliquer les règles du tennis à Andy Murray revient à enfoncer une porte ouverte. - Explaining the rules of tennis to Andy Murray is like teaching a fish to swim. 

This expression can also be used when someone repeats an idea:

• Je sais que je l'ai déjà dit dix fois, j'enfonce une porte ouverte, mais on ne peut pas être en retard pour le vol. - I know I have already said it ten times, I’m stating the obvious, but we cannot be late for the flight.

Read also: Understanding 'j'en ai marre': a deep dive into a common French expression

To whom do you say enfoncer une porte ouverte?

It is considered informal language which should be reserved for casual conversations with friends and family.

Be careful as this phrase could offend some people if a sarcastic or mocking tone is used.