What term describes someone's beliefs that are not necessarily provable?

The term that describes someone's beliefs that are not necessarily provable is "opinions." Opinions are personal views or judgments formed about something, which may not be based on absolute certainty or empirical evidence. They reflect what an individual thinks or feels, but these thoughts can vary significantly from person to person and are influenced by personal experiences, cultural background, and emotions.

When it comes to understanding how opinions differ from the other terms provided, facts are statements that can be proven true or false based on evidence. Assumptions are beliefs taken for granted without proof but may not represent personal views. Arguments involve presenting reasons or evidence to support a particular stance, typically about an opinion or point of view. Thus, opinions stand out as unique beliefs held by individuals that cannot be definitively proven, which makes them the correct answer in this context.