Probability in the past (estaría, sería...)

Wondering About the Past

In English, we guess about past events using phrases like "It must have been..." or "...was probably." In Spanish, you can express this same probability or conjecture simply by using the conditional tense.

For example, if you missed a party, you can use verbs like sería or estaría (must have been / was probably) to speculate about how it went.

The party must have been lively and the snacks very good.
La fiesta estaría animada y los bocadillos muy buenos.
The decoration was probably an incredible failure.
La decoración sería un fracaso increíble.
The event was probably packed and ended in the early morning.
El evento estaría repleto y terminaría en la madrugada.

"I wonder if..."

When you use the conditional tense to ask a question, it translates naturally to "I wonder if..." or "I wonder who / what...".

I wonder if the host was sad because we were absent.
¿Estaría triste el anfitrión porque estuvimos ausentes?
I wonder who arrived in the early morning while I was absent.
¿Quién llegaría en la madrugada mientras estuve ausente?
I wonder, were there seven or eight guests at the party?
¿Habría siete u ocho invitados en la fiesta?

Adding Context with "Seguramente"

If you are fairly confident in your guess, pair the conditional tense with an adverb like seguramente (surely / probably).

I wonder what they did; surely they were extremely happy.
¿Qué harían? Seguramente estarían felicísimos.