The aim of my paper is to distinguish groups of semantic motivations that have become the basis for the formation of words or word associations expressing obviousness. The study covered various European languages with particular emphasis on the Slavic languages. On the basis of the research, the following groups were distinguished: 1) knowledge and understanding; 2) sight, perception and clearness; 3) talking and adjudication; 4) nature; norm and custom; 5) consequence; 6) confidence, trust and security.

In the theory of open systems one mentions equifinality – by drawing from various sources, one may reach the same results. The new linguistic phenomenon, which emerged due to equifinality, upsets the stability of the system, causes various types of re‑evaluation, therefore the same source causes different results. Thus, one may speak about equipotentiality. In her article, the author demonstrates how the adverbia which emerged in the late part of the Proto‑Slavic period influenced the word‑formative system of the Polish language. She focuses on the adverbs with the formants ‑o and ‑e, a class which was thriving already in the earliest period of the written Polish language (more than 500 units in the Old Polish period).
In adjectives, the adverb influenced the gradual decline of intensifying prefixes prze‑ ( przedobry ‘extremely good’) and nad‑ ( nadpełny ‘Latin: superplenus’), and on the basis of the elative na(j)‑ and ‑ szy there emerged the morphosyntactic category of grade. The development of the category of disintensification took a different direction.
Adverbs were one of the reasons which caused the decline of diminutive and augmentative verbs. The traces of these categories are preserved in the following words used in the modern Polish language: głaskać ‘to fondle, to caress, to stroke gently’, nadskakiwać ‘to fawn, to flatter, to toady’. Adverbs also influenced the gradual decline of obsolete iterativa, their properties were assumed by adverbs ( palać – często palić ‘to smoke often’).
Many original adverbs shifted to the class of functional expressions, assuming a metatextual role – of commenting upon one’s own, current utterances. Sometimes they perform the functions of thematic operators ( Intelektualnie Marek ma cechy lidera, emocjonalnie absolutnie nie ‘Mark has the qualities of a leader intellect‑wise, but not at all emotion‑wise); rhematic operators (particles, e.g. Janek podobno wyjechał ‘Janek supposedly went away’), appositions: A pani czytała to? – Naturalnie! ‘And have you read it? – Naturally!’