Which argument type involves presupposing the truth of something without proving it?

The correct argument type that involves presupposing the truth of something without providing evidence to support it is a circular argument. Circular arguments assume the conclusion as part of the premise, thus failing to provide an independent proof for the claim being made. In a circular argument, the reasoning goes in a loop; the conclusion is essentially restated in the premises, making it seem valid while actually providing no real evidence or support.

For instance, if someone states that "reading is beneficial because it's good for you," they haven't offered any external proof to substantiate the claim; instead, they have restated the premise in a different form. This absence of independent verification is what characterizes circular reasoning.

Options like complex questions and argumentum ad logicam present different logical issues. A complex question involves posing a question that assumes a particular, often controversial premise is true, while argumentum ad numerum (the appeal to numbers) refers to using statistics or numerical facts to bolster an argument without addressing the issue at hand directly. These distinctions clarify why the correct choice is indeed circular arguments.