Demonstration is a valid syllogism made from warranted certain premises. Its premises may be immediate or inferential, provided the latter are genuinely grounded in certain principles.
The six classes are first principles, innate inferences, intuitions, observations, experiences, and mass-transmitted reports. Their epistemic routes—direct rational insight, an available middle term, immediate discovery, perception, repeated observation, and independent testimony—must not be conflated.
The textbook next distinguishes burhān limmī from burhān innī, depending on whether the middle term explains the real cause of the conclusion or only why the conclusion is known.