2, The Uses of Argument

"In 1958, Stephen Toulmin introduced a conceptual model of argumentation. He considered a pictorial representation for logical arguments, in which four parts are distinguished: claim, warrant (a non-deterministic reason which allows the claim), datum (the evidence needed for using the warrant), and backing (the grounds underlying the reason). Counterarguments are also arguments which may attack any of the four preceding elements. By chaining arguments a disputation can be visualised [applied later - 1991]. Today, Toulmin's work is essentially of historic interest." (taken from 'Logical Models of Argument' - Carlos Ivan Chesnevar - 2000)

Notes below taken from 'The Uses of Argument' (1958), by Stephen Toulmin

page 99 - D (data), So C (claim/conclusion), since W (warrant)
e.g. "Harry was born in Bermuda", So "Harry is a British subject", since "A man born in Bermuda will be a British subject".

page 101 - D, So, Q (qualifier), C, since W, unless R (rebuttal)
e.g. "Harry was born in Bermuda", So, "presumably", "Harry is a British subject", since "A man born in Bermuda will be a British subject", unless "Both his parents were aliens / he has become a naturalised American / ..."

page 104 - D, So, Q, C, since W, on account of B (backing), unless R
e.g. "Harry was born in Bermuda", So, "presumably", "Harry is a British subject", since "A man born in Bermuda will be a British subject", on account of "the following statutes and other legal provisions...", unless "Both his parents were aliens / he has become a naturalised American / ..."

However exhaustive the evidence provided by D and B together, the step from these to the conclusion C is not an analytic one.

Logical Gulf - the transition of logical type involved in passing from D and B on the one hand to C on the other. The epistemological question is what can be done about this gulf? Can we bridge it? Need we bridge it? Or must we learn to get along without bridging it?