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In the mid-20th century, philosophers and rhetoricians faced a pressing question: how should we evaluate arguments that occur in everyday language, in law, politics, and ordinary conversation? Formal logic, with its precise syntax and deductive validity, seemed too narrow to capture the richness of real-world reasoning. This tension drove the development of several interconnected frameworks that together define the field of informal logic and argumentation theory.
Two landmark works appeared in 1958, each proposing a radical departure from formal logic. Chaim Perelman's The New Rhetoric shifted attention from logical form to the audience. For Perelman, argumentation is aimed at gaining the adherence of an audience; its quality depends on shared values and the reasonableness of the auditor. Unlike formal logic, the New Rhetoric treated argumentation as a social process where norms arise from the audience's judgment, not from a fixed calculus.
At the same time, Stephen Toulmin's The Uses of Argument offered a structural alternative. Toulmin argued that the criteria for evaluating arguments vary across fields—a legal argument is judged differently from a scientific one. He proposed a six-component layout (claim, data, warrant, backing, qualifier, rebuttal) that captures the pragmatic reasoning of everyday disputes. While the New Rhetoric emphasized the context of persuasion, Toulmin's model provided a universal vocabulary for reconstructing arguments field by field. The two frameworks did not directly influence each other, but together they challenged the monopoly of formal logic and opened a space for studying argumentation on its own terms.
By the 1970s, a distinct North American movement took shape under the banner “informal logic.” Influenced by the earlier critiques of formalism, informal logic focused squarely on the analysis and evaluation of arguments in ordinary language. Its founding journal, Informal Logic, began publishing in 1978, and its leaders—Ralph Johnson, J. Anthony Blair, and others—saw the field as a normative enterprise. Unlike the descriptivism of the New Rhetoric, informal logic aimed to identify good and bad reasoning through the study of fallacies and dialectical obligations.
Informal logic borrowed from Toulmin’s emphasis on argument structure but pushed further toward a theory of argumentative norms. A key contribution was the concept of the “dialectical tier” (Johnson): an argument must not only present reasons but also anticipate and respond to objections. This built on the situational awareness of the New Rhetoric while rejecting its relativistic bent. Informal logic became the pedagogical bedrock for critical thinking courses, spreading widely in North American universities.
In the 1980s, Frans van Eemeren and Rob Grootendorst developed pragma-dialectics, integrating insights from pragmatics (speech act theory) and dialectics (regulated critical discussion). Their model prescribes a four-stage procedure for resolving a difference of opinion:
To guide this process, they formulated ten rules for rational discussion, including the freedom rule (parties may not prevent each other from advancing standpoints), the burden-of-proof rule, and the relevance rule. Violations of these rules constitute fallacies. Pragma-dialectics thus provided a systematic, normative alternative to both the New Rhetoric’s audience-driven standards and Toulmin’s field-dependent criteria. It also refined informal logic’s fallacy theory: where earlier informal logicians classified fallacies by type, pragma-dialectics defined them as moves that obstruct the resolution process.
By the 1990s, Douglas Walton and colleagues proposed another layer of analysis: argumentation schemes. These are stereotypical patterns of reasoning—like argument from expert opinion, analogy, or cause—each accompanied by critical questions that test its strength. Unlike the universal procedural rules of pragma-dialectics, schemes are content-specific: the evaluation of “expert testimony” requires different questions than “argument from consequences.”
Walton’s schemes complemented pragma-dialectics by providing concrete tools for analyzing arguments that occur in practice. At the same time, they challenged the assumption that a single set of rules suffices for all argumentation; the critical questions for a scheme reflect the particular type of reasoning involved. This made argumentation schemes especially useful for computational argumentation, artificial intelligence, and formal modeling, creating a bridge between informal logic and formal approaches.
All five frameworks remain active today, each serving distinct roles. The New Rhetoric informs communication studies and rhetorical criticism. Toulmin’s model is widely used in law, education, and AI for argument mapping. Informal logic continues to shape critical thinking curricula and fallacy research. Pragma-dialectics dominates European discourse analysis and debate theory. Argumentation schemes have become central in computational argumentation and AI, where they assist in reasoning about evidence and inference.
These frameworks agree on a core insight: argumentation is a social, context-dependent activity that cannot be reduced to formal validity. But they disagree on the source of normative standards. Pragma-dialectics locates norms in procedural rules for critical discussion; the New Rhetoric in audience acceptance; Toulmin in field-dependent criteria; argumentation schemes in reasoning patterns and their critical questions; and informal logic in dialectical obligations and fallacy analysis. This pluralism is a strength: different frameworks capture different aspects of real argumentation, and in practice, researchers often combine them. Current frontiers include integrating schemes with computational models of dialogue, testing procedural rules empirically, and developing hybrids that synthesize rhetorical effectiveness with dialectical rigor.
None of the frameworks has fully replaced the others; instead, the field has grown by preserving the insights of each while sharpening the questions that remain open.