Good Reasoning on the Toulmin Model

Some solo verbal reasoning serves the function of arriving at a correct answer to a question from information at the reasoner’s disposal. Such reasoning is good if and only if its grounds are justified and adequate, its warrant is justified, and the reasoner is justified in assuming that no defeaters apply. I distinguish seven sources of justified grounds and state the conditions under which each source is trustworthy. Adequate grounds include all good relevant information practically obtainable by the reasoner. The claim must follow from the grounds in accordance with a justified general warrant. If this warrant is not universal, the reasoner must be justified in assuming that no exception-making circumstances hold in the particular case to which it is applie

The Culture of Spoken Arguments

37 arguments were selected by random sampling methods from calls to radio and television phone-in programs. I discuss whether my general theory of inference evaluation applies to them and how frequently they exemplify a recognized argument scheme. I also compare their dependence on context, their complexity and their quality to those features of a previously studied sample of 50 scholarly arguments

Response to my commentator

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Material consequences and counter-factuals

A conclusion is a “material consequence” of reasons if it follows necessarily from them in accordance with a valid form of argument with content. The corresponding universal generalization of the argument’s associated conditional must be true, must be a covering generalization, and must be true of counter-factual instances. But it need not be law-like. Pearl’s structural model semantics is easier to apply to such counter-factual instances than Lewis’s closest-worlds semantics, and gives intuitively correct results