joka

The relative pronoun joka is the most common relative pronoun used to create complex sentences in Finnish. It refers to the noun phrase (the antecedent) immediately preceding the comma, which may include adjectives or genitive attributes. Here are the key rules for becoming proficient in its use:

• The Comma Rule: A comma is generally required before joka. When the sentence starts with the pronoun pair Se joka... (e.g., Se joka etsii, löytää or Se, joka etsii, löytää), the comma between 'Se' and 'joka' is optional. If the relative clause is in the middle of a sentence, you must also place a comma after the clause to 'fence' it off.
• No Omission: Unlike in English, where the relative pronoun can sometimes be dropped (e.g., 'The book I read'), the relative pronoun joka can never be omitted in Finnish.
• Agreement: If the noun you are describing is singular, use joka. If it is plural, use jotka.
• Case Selection: The case of joka depends on its role in the relative clause. For example, if it is a partitive object, use jota. If it is a total object, use the genitive form jonka in the singular, or the nominative plural jotka in the plural. However, if the verb in the relative clause is in the passive or is a necessity structure (e.g., minun täytyy), the singular total object must take the nominative case joka instead of jonka. For locations, use local cases like jossa (in which), and use the singular illative johon; the relative adverb jonne also expresses a destination. In the plural, use the stem joi- to form cases like the partitive (joita) or local cases (joissa, joihin).
• Postpositions: When using postpositions, use the genitive forms jonka (singular) or joiden (plural) before the postposition (e.g., jonka jälkeen - after which). Note that phrases like jonka jälkeen are notable exceptions where joka (in the genitive) is used to refer back to a whole clause, instead of the expected mikä.
• Joka vs. Mikä: Use joka when referring to a specific noun phrase. Use mikä when referring to a whole clause, an abstract superlative, or when the antecedent is the demonstrative pronoun se referring to an abstract concept (e.g., se, mikä...). However, if se refers to a person or a specific concrete thing, use joka (e.g., Se, joka ei syö lihaa...).

In formal writing, these clauses are sometimes replaced by participles to be more concise.

Antecedent and Word Order
Keep the noun phrase being described close to the relative clause: Näin tytön veljen, joka asuu Turussa normally says that the brother lives in Turku. To describe the girl instead, write Näin Turussa asuvan tytön veljen. With a superlative modifying a concrete noun, both paras kirja, jonka olen lukenut and paras kirja, minkä olen lukenut are accepted.