The word "more well-reasoned" denotes a carefully thought-out argument that is grounded in logic and evidence. Its opposite, then, would be a poorly-reasoned argument that lacks sound reasoning or evidence. Some antonyms for "more well-reasoned" might include "illogical," "unfounded," "unreasonable," "irrational," and "specious." These terms describe arguments that fail to provide strong evidence or rely on flawed logic. On the other hand, synonyms for "more well-reasoned" might include "logical," "rational," "coherent," "justified," and "sound." These terms describe arguments that are built upon careful reasoning and a solid foundation of evidence.