The Conditional Perfect
To talk about what would have happened in the past, use the conditional perfect.
Form it using the conditional form of the auxiliary verb olla (olisi-) plus the past active participle of the main verb (ending in -nut/-nyt, -lut/-lyt, etc.). Plural subjects take the plural participle (ending in -neet, -leet, etc.).
| Pronoun | Auxiliary | Participle (estää) | Meaning |
|---|---|---|---|
| minä | olisin | estänyt | I would have prevented |
| sinä | olisit | estänyt | you would have prevented |
| hän / se | olisi | estänyt | he/she/it would have prevented |
| me | olisimme | estäneet | we would have prevented |
| te | olisitte | estäneet | you (pl.) would have prevented |
| he | olisivat | estäneet | they would have prevented |
| The emperor would have avoided the revolution. | Keisari olisi välttänyt vallankumouksen. |
| The empire would have attacked the republic. | Imperiumi olisi hyökännyt tasavaltaan. |
| The allies would have attacked immediately. | Liittolaiset olisivat hyökänneet heti. |
Hypothetical Conditions with "Jos"
When creating "what if" scenarios, you will often use the word jos (if). Unlike English, which uses the past perfect for the "if" clause (e.g., "If he had lived"), Finnish uses the conditional perfect in both halves of the sentence.
| If the president had answered, we would have prevented the war. | Jos presidentti olisi vastannut, me olisimme estäneet sodan. |
| The empire would have won if the emperor had lived. | Imperiumi olisi voittanut, jos keisari olisi elänyt. |
"Would Have Had To"
To say someone "would have had to" do something, use the conditional perfect of the verb täytyä (olisi täytynyt). Because täytyä expresses necessity, the auxiliary is always the third-person singular olisi, and the subject is placed in the genitive case (ending in -n).
| The emperor would have had to escape. | Keisarin olisi täytynyt paeta. |