Comparison arguments, commonly identified by their specific types, i.e., a fortiori/maiori, a minori, and a simili, are a neglected topic in argumentation theory, legal reasoning, and logic. They are regarded as a kind of analogy, but in the history of dialectics, they were not considered as analogies. Their structure is reconstructed as a kind of syllogism, but the conclusion does not follow due to the formal properties of the argument. The material relation connecting premises and conclusion is that what holds for the more should hold also for the less (or the same judgment should hold for the same). But is this sufficient? And why should it be persuasive? This paper proposes an argumentation scheme approach to the structure of comparison arguments, which is developed based on insights from the dialectical tradition. Comparison arguments are claimed to be higher-order arguments that manifest a complex, deeper argumentative structure, represented through argumentation schemes. A fortiori is based on a mechanism similar to analogy, as it involves the abstraction of a functional genus, i.e., an abstract generic characteristic, and expresses further arguments. However, the inferential structure of a fortiori is distinguished by an asymmetry between the members of the comparison, i.e., a scalar paradigm. Moreover, at a deep level, it can be reconstructed as a bundle of implicit arguments in which the argument from commitment backgrounds or is backgrounded by other types of argument.
Fabrizio Macagno (Wed,) studied this question.