CHAPTER ONE On the Rhetorical Point of View. Why rhetoric declined, and what remained of it. Once upon a time rhetoric was a vast and influential branch of ...

Using persuasive definitions and persuasive language generally to put a spin on an argument has often held to be suspicious, if not deceptive or even fallacious. However, if the purpose of a persuasive definition is to persuade, and if rational persuasion can be a legitimate goal, putting forward a persuasive definition can have a legitimate basis in some cases. To clarify this basis, the old subject of definitions is reconfigured into a new dialectical framework in which, it is argued, a (...) definition should be evaluated in light of its purpose as a speech act. But if persuasive definitions are so often thought to be suspect, misleading, or even fallacious, how can individual cases be judged on some objective basis? In this paper, a new dialectical method of evaluating such definitions on a case-by-case basis is proposed, showing how abusive as well as reasonable uses of persuasive language can properly be identified, analyzed and evaluated. (shrink)

The recent redefinition of 'planet' that excludes Pluto as a planet led to controversy that provides a case study of how competing scientific definitions can be supported by characteristic types of evidence. An argumentation scheme from Hastings is used to analyze argument from verbal classification as a form of inference used in rational argumentation. The Toulmin-style format is compared to more recently developed ways of modeling such cases that stem from advances in argumentation technology in artificial intelligence. Using these tools, (...) it is shown how argumentation schemes, in particular argument from verbal classification and argument from definition to verbal classification, apply to cases of scientific argumentation. (shrink)

What are the implications of taking seriously Chaïm Perelman's proposition that “definitions are rhetorical”? Efforts to find Real Definitions are dysfunctional to the extent they direct argumentation toward pseudo “is” claims and away from explicit “ought” claims about how words are to be used. Addressing definitional disputes explicitly as propositions ofought rather thanis could put on the agenda the pragmatic concerns of definitional choice that might otherwise remain tacit.

In this paper we present an analysis of persuasive definition based on argumentation schemes. Using the medieval notion of differentia and the traditional approach to topics, we explain the persuasiveness of emotive terms in persuasive definitions by applying the argumentation schemes for argument from classification and argument from values. Persuasive definitions, we hold, are persuasive because their goal is to modify the emotive meaning denotation of a persuasive term in a way that contains an implicit argument from values. However, our (...) theory is different from Stevenson’s, a positivistic view that sees emotive meaning as subjective, and defines it as a behavioral effect. Our proposal is to treat the persuasiveness produced by the use of emotive words and persuasive definitions as due to implicit arguments that an interlocutor may not be aware of. We use congruence theory to provide the linguistic framework for connecting a term with the function it is supposed to play in a text. Our account allows us to distinguish between conflicts of values and conflicts of classifications. (shrink)

The purpose of this paper is to inquire into the relationship between persuasive definition and common knowledge (propositions generally accepted and not subject to dispute in a discussion). We interpret the gap between common knowledge and persuasive definition (PD) in terms of potential disagreements: PDs are conceived as implicit arguments to win a potential conflict. Persuasive definitions are analyzed as arguments instantiating two argumentation schemes, argument from classification and argument from values, and presupposing a potential disagreement. The argumentative structure of (...) PDs reveals different levels of disagreement, and different pos-sibilities of resolving the conflict or causing dialogical deadlock. (shrink)

The first part deals with the problem of the external form of ostensive definition. It is concluded that the definition statement is not complete. The proper form of this statement is not a sentence, but a sentential function, namely a sentential function of the type: ``Π x [N(x)=x is in the respect R and in the degree D such as A, B... and not such as K, L...]" where "N" stands for the term being defined. Thus the ostensive definition informs (...) about the criteria of applicability of the defined term in a partial way only, and the rest must be supplied by the addressee for whom the given definition was destined. In the second part the conditions are analysed on which depends the possibility of solving that problem, and consequently the conditions on which depend the informational value and the efficacy of ostensive definition. The concluding remarks deal with the properties of the terms introduced by the ostensive method. (shrink)

Practical methods are introduced for the construction of definitions, both for philosophical purposes and for uses in other disciplines. The structural and contentual requirements on definitions are clarified. It is emphasized that the development of a definition should begin with careful choice of a primary definiendum, followed by the selection of appropriate variables for the definition. Two methods are proposed for the construction of the definiens, the case list method and the method of successive improvements. Four classes of concepts are (...) discussed that are particularly difficult to define: vague concepts, value-laden concepts, controversial concepts, and inconsistent concepts. (shrink)