Reciprocal pronouns (toinen toistaan)

Reciprocal Pronouns: Each Other

To express that people do something to "each other," Finnish formally uses a distributive structure that repeats the word toinen.

This structure has two parts:

1. toinen (always in the basic nominative form)
2. toinen declined into the case required by the sentence, plus a possessive suffix matching the subject.

The possessive suffix changes depending on who is acting:

• me (we) adds -mme
• te (you plural) adds -nne
• he / plural nouns (they) add -nsa / -nsä or -Vn (a lengthened vowel + n)

The Partitive Form

If the verb takes a partitive object, or if it is used with a postposition that requires the partitive (like vastaan, meaning "against"), the second toinen becomes toista plus the suffix.

For third-person plural subjects (like miekkailijat, the fencers), the form is toinen toistaan (toista + an).

Adapting to Other Cases

If the verb or context requires a different case, the second toinen takes that case ending before the possessive suffix.

Illative (into): Verbs like luottaa (to trust) require the illative case (toiseen).

Ablative (from): Used when learning from someone (toiselta). If the subject is me, we add -mme.

Genitive (Possession): When expressing "each other's", the second toinen takes the genitive form (toisen). The genitive -n drops before possessive suffixes (e.g., toisen + mme becomes toisemme).

Allative (to): Used when bowing or speaking to someone (toiselle). For a third-person plural subject, it becomes toiselleen (toiselle + en).

Matching Other Persons

As seen in the ablative and genitive examples above, the possessive suffix always matches the subject. This rule naturally applies to the partitive case as well. For a subject like te (you plural), toista takes the suffix -nne.