"a theoretical argument" is a correct and usable phrase in written English.
You can use it whenever you are referring to an idea based on assumptions rather than facts or evidence. For example: "The professor presented a theoretical argument on why the economy might be affected by the new policy."
But this, too, is a theoretical argument.
"As a theoretical argument, it can be made," he said.
"One should never, ever use a theoretical argument for not measuring something," Dr. Tegmark said.
"This isn't just a theoretical argument – we're seeing it start to happen in some academies already.
There is a theoretical argument for resolving this perversity with a general election: to rehabilitate the authority of parliament it must be realigned with the post-referendum landscape.
They seemed to hope that they could win based on a theoretical argument about the inaccessibility of pain care to people without good insurance.
This fact, perhaps more than any theoretical argument, produced a strong realist reaction.
A new theoretical argument and a study of the temperature-dependent relaxation dynamics of helium show that defects may play an important role in describing its supersolid behavior.
For a general theoretical argument on this problem, we set up a model of a short conjugated molecular wire attached on both ends to metal electrodes.
First, while this study has a cross-sectional design, there is a strong theoretical argument why higher education may impact cerebral structures, cognitive performance, and CVD risk factors.
Although we cannot be completely sure of the reason why the effect disappears for the active localizer, this is a persuasive theoretical argument in favour of using a passive localizer, or at least one generated by an independent set of experimental conditions.
