# Can you use futur antérieur tense to make a guess about a past event?

• Ça les aura peut-être fait hésiter un peu. Et elle a pu en profiter pour les manipuler.

I thought that futur antérieur tense is equal to will have done in English and means future perfect.

But in this sentence, it does not make sense to think of this futur antérieur tense as meaning a future event, because in the next sentence a pu means a past event.

So maybe, futur antérieur tense (perhaps, when used with peut-être) is used in this example to make a guess about a past event?

• It is: might have made them hesitate a bit. Aug 5, 2017 at 15:13

The futur antérieur can have two different uses:

• Temporal function to express a completed future action:

Je t'appellerai quand je serai arrivé:

• Modal function to express probability or supposition in the past:

Il n'est pas encore arrivé, il lui sera arrivé quelque chose.

This is what is expressed in the sentence in your question.*

The use of the futur antérieur is enough to express probability, using an adverb to reinforce the degree of probability (peut-être, certainement, sans (aucun) doute...) is only optional.

If we compare with the use with the passé composé:

• Ça les a peut-être fait hésiter un peu. → peut-être is used to show the event is hypothetical.

• Ça les aura fait hésiter un peu. → the futur antérieur is used to the event is hypothetical.

We would use the conditionnel passé to show an even greater degree of uncertainty:

• Ça les aurait fait hésiter un peu.

in these last two sentences peut-être maybe just adding a little more doubts, maybe!

Further reference Le futur antérieur de l’indicatif, niveau B2

*In English, this probability is expressed by a modal verb ("must" "might"...) (It must/might have made them hesitate).