Antonyms for the phrase "deeming likely" could include words that convey uncertainty, improbability or doubt. Some examples of opposing words are improbable, unlikely, doubtful, questionable, uncertain, unsure, and incredulous. These words imply hesitation, suspicion or no faith in the likelihood of something happening or being true. Other antonyms could be affirmative phrases that denote certainty or strong belief, such as convinced, confident, or certain. Whether the antonym chosen represents doubt or conviction, it makes for a useful tool for comparison and contrast and can help elucidate the writer's or speaker's stance on a topic.