Ibtidāʾī: an ordinary, typically unemphatic statement for an uninformed hearer.
Ṭalabī: suitable reinforcement for a hesitant hearer.
Inkārī: one or more emphatic elements proportionate to the hearer's denial.
Important means of reinforcement include inna, anna, emphatic lām, oaths, attention particles, emphatic nūn, repetition, certain supplementary particles, qad and conditional ammā. Their grammatical uses are not interchangeable.
The central principle is to avoid both insufficient and needless emphasis. The next section of maʿānī concerns inshāʾ, whose primary function is not simply asserting a proposition as true or false.