Where does “päätäntäteoria” come from?

päätäntäteoria (Finnish) comes from Finnish teoria, from Late Latin theoria, from Ancient Greek θεωρός, from Ancient Greek θέα, from Proto-Hellenic *tʰáwā.

Ancestry of “päätäntäteoria”, step by step

päätäntäteoria traces back through two separate lines of ancestry.

via Finnish teoria

Step	Language	Word	Meaning
1	Finnish	teoria	theory
2	Late Latin	theoria	contemplation, speculation; speculation, theory
3	Ancient Greek	θεωρός	spectator; envoy sent to consult an oracle
4	Ancient Greek	θέα	view, sight
5	Proto-Hellenic	*tʰáwā	—

via Finnish päätäntä

Step	Language	Word	Meaning
1	Finnish	päätäntä	decision; conclusion
2	Finnish	päättää	to end, conclude, terminate, finish, bring to a close
3	Finnish	pää	head; end, tip
4	Proto-Finnic	pää	head
5	Proto-Uralic	päŋe	head

Every word from Proto-Hellenic *tʰáwā →Every word from Ancient Greek θέα →Every word from Ancient Greek θεωρός →