What term is used to describe an argument that is strong and has all true premises?

The term that accurately describes an argument that is not only strong but also has all true premises is a sound argument. A sound argument is one that meets two specific criteria: it must be valid, meaning that if the premises are true, the conclusion must logically follow, and it must also have all true premises.

While a cogent argument is strong with true premises, it is typically applied within informal logic and does not necessarily imply that the argument is valid in a strict logical sense. Therefore, although the term "cogent argument" highlights the strength and truth of the premises, it does not encompass the requirement of validity essential to the robust classification of an argument as sound.

In contrast, a valid argument does not require the premises to be true; it only ensures that the conclusion logically follows from the premises, regardless of their truth value. The phrase "indubitably true argument" is not a standard term in logic and does not correspond to the established definitions of argumentative strength or truthfulness.

Thus, the most fitting term for an argument that is both strong and has all true premises is sound argument.