Consonant gradation in the conditional

The Conditional and the Strong Grade

In the present tense, many verbs undergo consonant gradation, taking the weak grade when adding personal endings like -n (I) or -t (you).

In the conditional mood, however, the verb stem always uses the strong grade before the -isi- marker, regardless of the person acting.

If you know the third-person singular (hän) present tense of a verb, you already know its strong stem. Take that stem, adjust the final vowel if necessary, and add -isi-.

InfinitivePresent (minä)Conditional (minä)
kertoakerronkertoisin
ymmärtääymmärränymmärtäisin
antaaannanantaisin
rakentaarakennanrakentaisin
I would understand that this is my mistake.
Minä ymmärtäisin, että tämä on minun virheeni.
I would tell the truth if I were guilty.
Minä kertoisin totuuden, jos olisin syyllinen.
How would I build trust?
Miten minä rakentaisin luottamusta?

Other Verb Types

This rule applies consistently across verb types. For Type 3 verbs like riidellä and Type 4 verbs like loukata, the infinitive is weak, but the present and conditional stems both take the strong grade.

We would not argue every day.
Me emme riitelisi joka päivä.
I would not offend you on purpose.
Minä en loukkaisi sinua tahallaan.
How would you solve this argument?
Miten sinä selvittäisit tämän riidan?
I would know that you are lying.
Minä tietäisin, että sinä valehtelet.
The boss would find the guilty person if he saw the bad behavior.
Pomo löytäisi syyllisen, jos hän näkisi huonon käytöksen.