The II infinitive is formed as follows:
Examples: tulla : tullen : tullessa : tullessani : tullessasi : tullessaan : tullessamme : tullessanne and kulkea : kulkien : kulkiessa : kulkiessani etc.
In addition, the inessive of the II infinitive has a 4th person form, constructed in a different way: change the iin ending in the 4th person past tense form to e, then append the inessive suffix. Examples: sanoa : sanottiin : sanottaessa; tulla : tultiin : tultaessa; kulkea : kuljettiin : kuljettaessa.
The II infinitive has only the two case forms mentioned, the inessive and the instructive, but it is frequently used in written language. However, the actual usage often violates the rules of standard Finnish.
In principle, the inessive of the II infinitive indicates the time of an action only, e.g. sanoessa means “while saying, when saying, during saying”. Thus, it is used to construct a temporal clause equivalent. However, in written language, this form often has other, nonstandard uses.
The following is correct use: Tämä tapahtui Kekkosen eläessä (This happened when Kekkonen was still alive). However, the form is often misused as in Paavo voitti Pekan tullessa toiseksi, instead of the more correct Paavo voitti ja Pekka tuli toiseksi (Paavo won and Pekka was the second); this statement does not actually mean that the things happened at the same time. It also misused to express a condition, e.g. Sateen sattuessa menemme sisälle, which formally means “During an event of rain, we go inside”, but in practice “If there will be rain, we will go inside”.
The possessive suffix in the inessive form specifies the agent of the action expressed by the form. Thus, tullessani means “during my coming”, i.e. “when I was coming/came/will come”. The 3rd person has special rules. In Ville toi lahjan tullessaan (Ville brought a present when he came), the possessive suffix an refers to the subject of the sentence. A possessive suffix is not used in an expression like Täällä satoi Villen tullessa (It was raining here when Ville came), where the agent is not the subject of the sentence but expressed by an attribute, a noun in the genitive, here Villen. When the attribute is a 3rd person pronoun, hänen or heidän, a possessive suffix is used: Täällä satoi hänen tullessaan (It was raining here when he/she came),
The 4th person form of the inessive means that the agent of the action is unspecified, as in 4th person in general. Compare:
It is very common to use the 3rd person form without a possessive suffix instead of the 4th person form, e.g. Olin nuori tätä taloa rakentaessa, but this may leave it to the reader to guess which of the above alternatives is meant. However, a 3rd person form is correct when it refers to a generic person the same way as the predicate of the sentence, e.g. Nyt näkee paljon sieniä metsässä kävellessä (Now you see a lot of mushrooms when you walk in the woods). Debatably, a 3rd person form, used in a generic meaning, can be regarded as correct in some other contexts, too, e.g. in Näillä seuduilla liikkuessa on hyvä kartta tarpeen (When moving around these areas, a good map is needed); here the 4th person form liikuttaessa is another possibility and undeniably standard.
The expression of the agent in II infinitive inessive forms in standard Finnish can be summarized as follows:
Some inessives of the II infinitive are used as adverbials or postpositions that are no longer governed by the rules above. For example, tullessa can be used as an adverbial meaning “on the journey here” in Tullessa pysähdyimme Jyväskylässä (On the way here, we stopped in Jyväskylä). The form mennessä is commonly used as a postposition meaning “at the latest” or “by”, e.g. maanantaihin mennessä (by Monday, i.e. on Monday at the latest); no possessive suffix is used in such contexts. On the other hand, tullessa and mennessä are also used as regular infinitives of tulla and mennä.
The instructive of the II infinitive does not usually indicate an instrument or method but simultaneous or accompanying action, e.g. He kävelivät keskustellen politiikasta (They had a walk, discussing politics). Thus, its meaning is close to that of the inessive, but the construct formed, contextual clause equivalent, has a different purpose. He kävelivät keskustellen politiikasta says that they walked and simultaneously discussed politics, whereas He kävelivät keskustellessaan politiikasta says that they walked while they were discussing politics, making the discussion the primary thing here.
This form associates with the subject of a clause, so e.g. in Pekka voitti jättäen Paavon toiseksi, it refers to what Pekka did: Pekka won, leaving Paavo on the second place. Such usage is standard, but literary only; in speech, we would say Pekka voitti ja jätti Paavon toiseksi. As with the inessive, nonstandard usage is common. For example, Pekka voitti Paavon vuonna 2013 häviten hänelle vuonna 2014 does not comply with the standard rules, since it says that Pekka beat Paavo in 2013 (simultaneously) losing to him in 2014.
Several II infinitive instructive forms are used as adverbs or prepositions, losing much if not all of the connection with their nominal meanings. For example, riippuen usually means “depending on…”, used with the elative, e.g. riippuen säästä (depending on the weather), and it seldom has the literal meaning “hanging from”). Other examples:
These forms are mostly literary and often frowned upon in language guides, which suggest e.g. using tämän takia instead of tästä johtuen. However, especially riippuen has become common even in informal language and is often difficult to replace.