determination

doggedness, obduracy, obdurateness, obstinacy, obstinateness, perseverance, persistence, persistency, stubbornness, tenaciousness, tenacity

certainty, certitude, confidence, sureness

alacrity, eagerness, gameness, readiness

backbone, fortitude, grit, iron, pluck, sand

behest, charge, commandment, decree, dictate, directive, edict, instruction, mandate, order, word

last word, say-so

adjudication, disposition, doom, finding, ruling, sentence

choice, option, selection

consensus

belief, conviction, eye, feeling, mind, notion, persuasion, sentiment, view

decision, deliverance, diagnosis, judgment (or judgement), resolution, ruling, verdict

conjecture, guess, surmise

assumption, presumption, supposition