A Dialectical Tier Within Reason

The first part of this essay argues that the specification of rationality operating in Manifest Rationality does not allow for the inclusion of the dialectical tier as a necessary component of a rational product. It next considers Perelman's conception of "reasonableness" as an alternative to Johnson's structural sense of rationality. Adopting a contextually rich conception of rationality, like that of Perelman, allows Johnson to insist that a rational product must consist of both an illative core and a dialectical tier.

The Significance of Informal Logic for Philosophy

Informal logic is a new sub-discipline of philosophy, roughly definable as the philosophy of argument. Contributors have challenged the traditional concept of an argument as a premiss-conclusion complex, in favour of speech-act, functional and dialogical conceptions; they have identified as additional components warrants, modal qualifiers, rebuttals, and a dialectical tier. They have objected that "soundness" is neither necessary nor sufficient for a good argument. Alternative proposals include acceptability, relevance and sufficiency of the premisses; conformity to a valid argument schema; conformity to rules for discussion aimed at rational resolution of a dispute. Informal logic is a significant part of philosophy.