(I'm posting this here so I can explain it one time in one place.)
The Italian future tense is often used where English uses the present tense with modifiers like "I guess" "I suppose" "I wonder" etc.
Saranno le otto means "It must be eight" or "It's probably eight" etc. It could mean "It will be eight" in the right context, of course, but context should make this easy to figure out.
"A Reference Grammar of Modern Italian, Second Edition" (Maiden and Robusttelli, 2007, section 15.5)
In the Duolingo Italian "V. Future" skill we see this example:
She will know how to swim.
She must know how to swim. (Rejected as of 2014-8-14)
The first line is the Italian prompt. The second line is Duolingo's suggested translation. The third line is my translation assuming conjectural future. The Duolingo translation is a bit odd, but if we're creative we can imagine a context where it could work. (E.g a father talking about his daugher's plans to go to a camp that requires you know how to swim.) The conjectural one, however, is a lot more natural.
The problem is much more serious in the "Fut. Per." skill. The conjectural Italian future perfect corresponds to the English present perfect, and we get examples like this:
Dove avrai vissuto primo di allora
Where will you have lived before that?
I wonder where you lived before that?
Naturally the results are terribly confusing to people. Duolingo accepts at least some of the more natural translations, but the ones it offers are often highly unnatural English. Here are a few more examples:
Lui sarà stato il tuo nemico peggiore.
He will have been your worst enemy.
He must have been your worst enemy. (Confirmed that Duo accepts this.)
Che cosa avrà potuto fare lui?
What will he have been able to do?
I wonder what he managed to do?
Tu sarai stato già all’estero.
You will have already been abroad.
You must have already been abroad.
Avrete potuto nuotare in piscine.
You will have been able to swim in the pool.
You must have managed to swim in the pool.
Avrai potuto capire meglio il sentimento.
You will have been able to understand the feeling better.
You must have managed to understand the feeling better.
I'll update this to correct errors or to improve the explanation.
This commenter is apparently unfamiliar or uncomfortable with the English future perfect tense, which is also a valid choice when there is no context to indicate otherwise. The Italian future perfect tense can function in exactly the same way that the English future perfect tense does. You don't have to take my word for it. You have access to the same Internet that I do. The above dissertation sounds very authoritative, but it is biased and only tells half the story.
Spero che per quando arriviamo sarà stato aperto
I hope that by the time we arrive it will have been opened
Avrai lavorato tutto il giorno
You will have worked all day
You must have worked all day
Una volta che ci saremo conosciuti, lei capirà
Once we have met, she will understand
Once we will have met, she will understand
Mio figlio mi avrà chiesto mille volte
My son will have asked me a thousand times
My son must have asked me a thousand times
Sarà stata chiamata così in onore della zia
Deve essere stata chiamata così in onore di sua zia
She must have been named so in honor of her aunt
She will have been named so in honor of her aunt
L'avrai conosciuta da/per non più di tre ore
You will have known her for no more than three hours
*Perché avrà lasciato suo/il marito?
Why will she have left her husband?
Quando arriverò/arrivo non avrò ancora fatto colazione
When I arrive I will not have had breakfast yet
Dopo tre giorni non avrai creduto a̶l̶la verità
After three days you will not have believed the truth
Avrò guardato tutti i treni prima del tuo arrivo
I will have watched all the trains before your arrival
Lui non (ci) avrà pensato due volte
He will not have thought twice
Si sarà chiesta perché
She will have asked herself why
Forse (lui) avrà parlato di me
Maybe he will have talked about me
Loro due si saranno lasciati già
The two of them will have left each other already
Sarà stata/o usata/o per qualcos'altro
It will have been used for something else
La partita ti sarà piaciuta
You must have liked the match
You will have liked the match
Saprete quando sarà venuta l'ora
You will know when the time has come
You will know when the hour comes
You will know when the time will have come
A quel punto saranno andati via da qui
At that point they will have gone away from here
Chi avrà preso il mio dentifricio?
Who can have taken my toothpaste?
Who will have taken my toothpaste?
Per la settimana prossima la strada sarà stata aperta al pubblico
By next week the road will have (been) opend to the public
Tra un mese la decisione sarà sicuramente stata presa
In a month the decision will definitely have been taken/made
I struggled through this skill. It's very hard to grasp what is going on when you can't even make sense of the English 'answers'. This is one of those sections where an introduction to explain what on earth is going on would be really helpful.
Your answers above certainly make it a lot clearer, thank you.
"I will have known the same thing" is so weird I have trouble imagining anyone ever using it--and I have a pretty good imagination.
It's hard but not impossible to invent a context where either of the last two works in English. I'm visualizing a old person trying to explain something he/she wrote many decades ago. "Today we know X. I must have known the same thing back when I wrote this." For the other one, "I probably knew the same thing, once; I just don't remember anymore."
Again, saupto usually works better as "found out" or "learned" rather than "knew."
"I probably learned the same thing, back when I was your age, but, of course, I don't remember any of it now."
Helpful comments. Thanks, Greg. I think all of DL's Italian prompts also can be translated using "would have", plus the verb. Using some of your DL examples: where would you have lived before that; what would he have been able to do; you would already have been abroad. At least, that's likely how I would say it in English!
This section makes sense if I think about it like George Clooney is explaining the plan in Ocean's Eleven:
"Brad Pitt will distract the attorney, and by the time he is done, Julia Roberts will have befriended the mayor"
"By the time they get home, we will have already robbed the casino"
Hey, that's great. From your explanation I just figured out, that we have the same structure in German.(At least for the Simple Future) I had never occurred to me before. Saprà nuotare She will know how to swim. Sie wird (schon) schwimmen können. Saranno le otto means "It must be eight" Es wird acht Uhr sein. Thanks a lot for this explanation!
All these suggestions are so great! Thanks! But... I don't understand one thing: The Italian future perfect tense is not about the future?? In the example below by gmcolletti, "Avro saputo la stessa cosa" (s)he suggest two translations that mean two very different things in English. "I will have known the same thing", while awkward is about the future, while "I must have known the same thing" is referring to the past. So, if the second is the correct translation, then the Italian fut.perf. is actually referring to the past, not the future. Is this correct??
Same with your example here. Which of these two answers is correct? Because they can't both be (I don't think! hahaha!)
"Dove avrai vissuto primo di allora?"
-- "Where will you have lived before that?" -- referring to the future
-- "I wonder where you lived before that?" -- referring to the past
My understanding is that future perfect in Italian is used either when an action will be completed in the future / out of two future actions one happened earlier, or when you want to express uncertainty about a past action, similarly to simple future. So basically it can refer both to the future and the past.
I think the fact that it's in second person makes it more confusing.
It might be easier to understand in a context where we're using third person and talking about someone who isn't there. For example, looking at a family history. Say you're reading your great-aunt's diary from when she was 30 years old and living in Florence, but you don't know anything about her life before then. You might say to yourself
'Dove avrà vissuto primo di allora'? -- 'I wonder where she lived before that?' or maybe 'Where would she have lived before that?'
I just tried this on Google Translate, with interesting results. The three Italian sentences: "Dove avrai vissuto prima di allora?" "Dove hai vissuto prima di allora?" and "Dove avevi vissuto prima di allora?" all translate as "Where did you live before?" At least Google Translate was able to see that "Dove avresti vissuto prima di allora?" has a different meaning: "Where would you have lived before then?" Not that Google Translate is at all authoritative, but I was surprised that it cannot help us at all with something as elemental and distinguishing between these different perfect tenses. But, it suggests that locating the future perfect in the past isn't a completely wacky thing to do.
E lo stesso in Greco. I guess (as I'm only a beginner) it SOMETIMES helps to think of it as will + imperfect i.e. there will be a point in time when you will ALREADY have been in the process of the action of the verb for a continuous amount of time/or as a habit (You - the OP - translate it with "have managed to", I express it with quite a few more words). If you think of it as a future imperfect and a future perfect it will make sense.
This happens because I guess italian rolls "will have" (future perfect) and "would have" tense (conditional FUTURE TENSE) into one tense. So there is a dual use for it that goes beyond English. Maybe it will become more intuitive if I deconstruct the greek tenses for you in an english/italian way -> (Θα έχω μιλήσει) You will + have + spoken -> avrai parlato (future perfect), will + had + spoken (θα είχα μιλήσει) (transitions to would have in English)-> avrai parlato (future perfect conditional). The "would have" then transitions to your "must have" as a logical assumption. This is not a very good explanation but I'm sure that if one goes deeply into Greek verb grammar, they will understand the way Italian is with this thing here. The problem is that English have mixed everything up with modals while in Greek (therefore Latin?) there are more extensively constructed tenses with various aspects and modalities.
Very interesting! Great work! You must have given this a lot of thought and analysis. Μπραβο! (Θα εχω μιλησει = I will have spoken = avrò parlato. Θα ειχα μιλησει = I would have spoken = avrEI parlato. Θα εχεις μιλησει = you will have spoken = avrai parlato. Θα ειχες μιλησει = you would have spoken = avresti parlato)
I think this example really lays bare the fact that DL is not a comprehensive way to learn a language. I think it's great, not least because it so motivates you to do some every day, but you can never learn a language fully by pulling sentences out of context. Languages are always in context. You have to immerse yourself!