The antonyms for the word "most presupposed" are less presumed, less assumed, less expected, less anticipated, and less conjectured. These antonyms indicate the opposite of what is commonly believed or expected. They suggest a lack of certainty, and the absence of ultimate foundation of belief or knowledge. For instance, if one claims that most presupposed idea about politics is that candidates are dishonest, then the antonyms for the word presupposed would be the opposite belief, such as that most politicians are sincere, frank, and open-minded. In sum, antonyms for "most presupposed" reject ideas, notions, or presumptions that are not necessarily backed up by facts or rigorous reasoning.