Most unreasoning refers to a lack of rationality or logic in decision making. Antonyms for this phrase could include reasonable, logical, sensible, and justified. These words imply that there is a basis for a conclusion or decision that is arrived at with careful thought and analysis. Other antonyms could include intelligent, astute, shrewd, or discerning, all of which suggest a level of wisdom and cunning in decision making. Ultimately, the antonyms for most unreasoning all imply that the individual making the decision or conclusion is thoughtful, perceptive, and has considered and analyzed all available information before arriving at a decision.