from Foss et. al on Stephen Toulmin:
Born 1922 in London. Educated in sciences, math, and philosophy. Practical experience in the military. Driving interest: rationality. What does it mean to use human rationality? His work places particular emphasis on the paradoxes in the standing contrasts between "substantive" and "formal" aspects of reasoning and argument. As with Perelman, a European unaware of the rhetorical tradition in speech in America until after his primary works of contribution had been written. Also, another thinker who is primarily dismissed by philosophers.
FORMAL ARGUMENT AND ITS IRRELEVANCE TO PRACTICAL REASON: First, he rejects that traditional philosophers came to know immutable standards for rationality. His major criticism here is that formal logic is based on mathematics: a highly specialized and technical field of argumentation, the premises and methods of which are not appropriate to all fields. In a large part, because of the importance of the human "doer" in natural argument fields (as opposed to the numerical, non-human doer in everyday argument fields and activities). Secondly, because logic assumes a timelessness which is not present in human affairs. Third, he rejects the proposal that standards are completely relativistic depending wholly on place and time. His complaint is that wholly relativistic operations produce no standards at all. Instead, he searches for a "new epistemic self-portrait."
ELEMENTS OF PRACTICAL LOGIC The Layout of Argument: The Toulmin model for argument: based on legal rather than formal processes. The crucial term of this model is JUSTIFICATION--"reasoning is thus not a way of ARRIVING AT IDEAS but rather a way of TESTING IDEAS CRITICALLY. It is concerned less with how people think than with how they share their ideas and thoughts in situations that raise the question of whether those ideas are WORTH sharing." So the question becomes the standards by which arguments succeed or fail to provide justification for claims.
MODEL terms: terms which specify "force" (how strong is the claim) and "criteria," (the standards used to justify the claim). The model: claim, grounds, warrant, backing for the warrant, modal qualifier (strength of the step taken from data to warrant), rebuttal (qualifier).Argument fields vary according to their degree of formality, precision, and their modes of resolution. Argument fields which are either field dependent or invariant. The standards for judgment also vary by field.
EVOLUTIONARY MODEL OF CONCEPTUAL CHANGE An answer to T.S. Kuhn's Structure of Scientific Revolutions: that conceptual change is more evolutionary than revolutionary (this is, of course, a much more traditional point of view). A major component of Toulmin's argument is that scientists working in "competing" paradigms do very often manage to argue--every step of the way. Toulmin uses Darwin as a model: concepts develop by way of innovation and selection (variation and its perpetuation). The argument over cold-fusion is a perfect example. Innovation: new ideas are thrashed out by "a forum of competition." The surviving ideas are selected as replacements or revisions for currently held notions. In short: rationality occurs when "rational enterprises" provide forums of criticism for ideas, neither absolute nor relative. (quote on page 93 about "all clearheaded men"--the universal audience) Evaluations are always a matter of comparison. We should be more interested in IMPROVEMENT than with VALIDITY OR INVALIDITY. The impartial rational standpoint is generally objective, but always subject to reconsideration. Argumentation involves explanation and criticism, persuasion, and human interaction. Rationality is constituted by rhetorical processes.
ARGUMENT AND CONCEPT EVALUATION AS RHETORICAL PROCESSES. Even formal appeals must be discussed discursively. Further, nature has no language by which to speak--only through human mediation does even the scientific world make its meanings known.