 The distinctive mark of demonstrative arguments—certainty—is characterized in terms of assertion. An assertion p is certain if and only if  one holds (i) the justified belief that p and (ii) the justified belief that p cannot be otherwise; a demonstrative argument is one in which certainty is transferred from premises to conclusion. Demonstrative assertions are explicitly identified by Avicenna in the framework of a broader classification of various types of assertions of decreasing epistemic strength (certain, endoxic, suppositional, fallacious), which are in turn associated with a canonical taxonomy of logical disciplines (demonstration, dialectic, rhetoric, sophistic) (Gutas 2012; Hasnawi 2013; Black 1990).