Unreal past conditions
To talk about how things could have been different in the past, we use unreal past conditional sentences. These describe a hypothetical past situation and its hypothetical past result—perfect for discussing how historic accidents or catastrophes could have been avoided.
To form these sentences, use si (if) followed by the past perfect subjunctive, and then state the result using the conditional perfect.
You already know that the conditional perfect uses habría + a past participle. The past perfect subjunctive uses the imperfect subjunctive of haber + a past participle.
| Pronoun | Form of haber (past perfect subjunctive) |
|---|---|
| yo / él / ella / usted | hubiera |
| tú | hubieras |
| nosotros / nosotras | hubiéramos |
| ellos / ellas / ustedes | hubieran |
| If they had investigated, they would have prevented the tragedy. | Si hubieran investigado, habrían prevenido la tragedia. |
| If the ship had had radar, it wouldn't have crashed into the iceberg. | Si el barco hubiera tenido radar, no habría chocado contra el iceberg. |
| If the radar had worked, it would have warned the captain. | Si el radar hubiera funcionado, habría advertido al capitán. |
Changing the clause order
Just like in English, you can flip the order of the sentence. You can state the hypothetical result first (conditional perfect), followed by the si clause (past perfect subjunctive).
When the si clause comes second, you usually do not need a comma to separate the two halves of the sentence.
| We would have prevented the explosion if there hadn't been negligence. | Habríamos prevenido la explosión si no hubiera habido negligencia. |
| The tragedy wouldn't have happened if they had seen the iceberg in time. | La tragedia no habría sucedido si hubieran visto el iceberg a tiempo. |
"There would have been"
To say "there had been" or "there would have been" (referring to the existence of something, like victims or an explosion), use the impersonal forms of haber combined with its own past participle, habido.
- hubiera habido = there had been
- habría habido = there would have been
| If the government had helped, there wouldn't have been victims in the tragedy. | Si el gobierno hubiera ayudado, no habría habido víctimas en la tragedia. |
| The important thing is that, if he hadn't smoked, there wouldn't have been an explosion. | Lo importante es que, si no hubiera fumado, no habría habido una explosión. |