hänen mielestään

These constructions are the standard way to attribute thoughts or information to a person or group.

1. The Genitive Requirement
The person whose opinion is being shared must be in the genitive case. If it is a pronoun, you use minun, sinun, hänen, meidän, teidän, or heidän.

2. The Postposition and Suffix
When using a personal pronoun, the postposition takes a possessive suffix. The 3rd person suffix has two variants: -nsa/-nsä and -Vn (lengthening the final vowel + n). For words ending in a short vowel like mielestä, the -Vn variant is typically used. However, for words like mukaan, which ends in the consonant 'n', the final 'n' drops before the possessive suffix is added, leaving a stem ending in a long vowel (mukaa-). Because it ends in a long vowel, the -nsa/-nsä variant must be used. This suffix follows vowel harmony:

• (minun) mielestäni (in my opinion)
• hänen mielestään (in his/her opinion - front harmony)
• hänen mukaansa (according to him/her - uses -nsa because of the long vowel stem)

3. Nouns vs. Pronouns
Crucially, if the owner is a noun (like Pekka or opettaja), the postposition does not take a suffix: Pekan mielestä (in Pekka's opinion), not Pekan mielestään.

4. Dropping the Pronoun and Reflexivity
In standard Finnish, you can omit minun, sinun, meidän, and teidän because the suffix is unique. However, dropping the 3rd person pronouns hänen and heidän changes the meaning. If omitted, the suffix becomes reflexive and refers back to the subject of the sentence (e.g., Hän on mielestään oikeassa = He is, in his own opinion, right). If the opinion belongs to someone other than the subject, hänen or heidän must be included (e.g., Hänen mielestään hän on oikeassa = In his [someone else's] opinion, he is right).

5. Key Expressions and Alternatives

• mielestä-: Used for subjective judgments. Derived from mieli (mind) + elative case.
• mukaan: Used for citing sources. Note: With a personal-pronoun source, use the possessive suffix (hänen mukaansa). A noun or demonstrative source does not trigger it: uutisten mukaan, sen mukaan, tämän mukaan. A noun naming a person follows the same noun rule: Pekan mukaan.
• minusta / sinusta / hänestä: A very common alternative to mielestäni is using the elative case of the pronoun itself. For example, Minusta se on hyvä means exactly the same as Minun mielestäni se on hyvä.

6. Register Differences
In formal writing (kirjakieli), the suffix is required in these constructions with personal pronouns. In natural spoken Finnish (puhekieli), however, possessive suffixes are often dropped, even in these common expressions (e.g., mun mielestä instead of minun mielestäni). Furthermore, 3rd person pronouns are typically replaced by sen and niiden (e.g., sen mielestä, niiden mielestä).