Perusteen

Perusteen is a Finnish noun form: it is the genitive singular of peruste, which means basis, foundation, or reason. In everyday and formal language, perusteen appears in phrases that refer to the grounds or justification for a claim, decision, or statement. It is most often used to indicate what something is built on or what supports it.

In usage, perusteen conveys the idea of a supporting basis rather than the basis itself. It is common in legal, academic, and journalistic texts to discuss what lies behind a conclusion or action. Two frequent constructions are perustu en mukaan, meaning according to the basis, and perusteen perusteella, meaning on the basis of the basis or on the grounds provided by the basis. The form helps link a claim to its underlying cause, evidence, or rule.

The word belongs to a family built around the concept of foundation. Related forms include perustaa (to base or establish), perusta (basis or foundation in a more tangible sense), and perustus (foundation or constitution in specific contexts). This family is widespread in Finnish, reflecting the central role of justification and grounds in argumentation, law, and everyday reasoning.

See also: peruste, perusta, perustus.