Yes, DETERMINISM is a Scrabble word!

Letter values in Scrabble US: D 2, E 1, T 1, E 1, R 1, M 3, I 1, N 1, I 1, S 1, M 3.

Is it a valid word?

DETERMINISM is a valid word in the official Scrabble dictionary (US), the UK Scrabble Dictionary and Words with Friends (ENABLE).

(philosophy) a philosophical theory holding that all events are inevitable consequences of antecedent sufficient causes; often understood as denying the possibility of free will