Practical argumentation, i.e., argument about what to do, should be treated as a separate sub-domain in argumentation studies, distinct from epistemic argumentation (argumentation about what is true). The former is multi-dimensional, the latter is in principle one-dimensional. Also, the multiple dimensions are typically incommensurable. This makes a step from descriptive argument mining to normative argument assessment problematic. Subjectivity is necessarily and legitimately involved, and scalar computation of argument merit is impossible. On the other hand, normative assessment of practical argumentation, based on criteria, is possible and necessary.

The domain where all this is the case has since antiquity been the core domain of rhetoric, and the rhetorical tradition has much to contribute to the understanding of it.