The term "pro position" typically refers to a statement or argument that is in favor of something. Antonyms for pro position would therefore include terms that refer to arguments or stances that are against something, such as "anti position" or "con position". Other common antonyms might include terms like "opposition" or "rejection", which indicate disagreement with a particular stance or argument. Ultimately, the choice of antonym will depend on the specific context in which the term is being used, as well as the underlying beliefs and values that inform the argument at hand.