The Long First Infinitive: tehdäkseni

To say "in order to" — to express the purpose behind an action — Finnish has an elegant, compact construction built entirely on the first infinitive: the long first infinitive, also called the translatiivi-infinitiivi. You take the dictionary form, add the translative -kse-, and finish with an obligatory possessive suffix that agrees with the subject of the main clause: tehdäkseni "so that I do," mennäkseen "so that he/she goes."

It is one of the most characteristic features of good written Finnish, and it hides one strict grammatical rule that English speakers routinely break. Master both the shape and the rule and your Finnish will jump a register.

How to build it

Take the first infinitive whole and add -kse- plus the possessive suffix. Nothing is removed:

puhua + -kse- + -ni → puhuakseni tehdä + -kse- + -ni → tehdäkseni mennä + -kse- + -en → mennäkseen

The full possessive set:

The third-person form ends in -kseen (the -Vn possessive, where the vowel copies the e of -kse-): ostaakseen, mennäkseen, tehdäkseen. A literary variant -ksensa/-ksensä also exists (tehdäksensä), but -kseen is the everyday written form. Note there is one form for both hän and he.

Two watch-points in the spelling

The -kse- vowel is fixed. It is always -kse-, with e — it does not harmonise, because e is a neutral vowel. Only the infinitive body ahead of it carries harmony. So it is puhuakseni (back-vowel body) and tehdäkseni (front-vowel body), but the -kse- itself is identical in both.

The possessive suffix is fixed too. -ni, -si, -kseen, -mme, -nne never change their vowels. The single most common misspelling — *tehdaksemi — makes three errors at once: it drops the front vowel ä of the infinitive, wrongly harmonises -kse-, and mangles -ni into -mi. The correct form is tehdäkseni, full stop.

What it means: purpose

The long first infinitive answers "what for?" — the goal that motivates the main action. English uses "(in order) to," "so as to," or a "so that I could…" clause.

The rule English speakers break: same subject

Here is the constraint that makes or breaks this construction. The possessive suffix must agree with the subject of the main clause, and the person who carries out the purpose must be that same subject. The long first infinitive is a shared-subject form: one actor does the main action and the intended action.

In Menin kauppaan ostaakseni maitoa, it is I who went and I who buys — one subject, so -kseni is legal. You cannot use this construction when the purpose has a different actor. English lets you say "I gave him the key so that he could get in," but Finnish cannot pour that into a long infinitive, because he ≠ I. There you must switch to a finaali clause with jotta (or että) and a finite verb:

Compare the minimal pair directly. When the subject is shared, both are available, but the infinitive is tighter:

Two more limits

It is affirmative only. You cannot negate the long first infinitive. "In order not to be late" is expressed with a jotta en / ettei clause: Lähdin ajoissa, jotta en myöhästyisi "I left in time so as not to be late," or the set adverbial ollakseni rehellinen "to be honest" resists negation entirely.

It is written and formal in tone. In casual speech many Finns replace it with a purpose clause or the postposition construction sitä varten että…. Recognise it everywhere in the news and literature; use it when you want your Finnish to read as educated and precise. This is part of the broader register split covered on the genitive-infinitive and non-finite constructions page.

Common Mistakes

Key Takeaways

• The long first infinitive = first infinitive + -kse- + possessive suffix and means "in order to."
• Forms: -kseni, -ksesi, -kseen, -ksemme, -ksenne; the 3rd person is -kseen (for both hän and he).
• Build off the infinitive, not the present stem (tehdäkseni, not *teenkseni); -kse- and the possessive never harmonise.
• Strict rule: the purpose-doer must be the same as the main-clause subject. Different subject → use a jotta clause instead.
• It is affirmative-only and formal/written in register.