Reviews the scope, nature, and applications of the philosophical discipline, focusing on methods for distinguishing between valid and fallacious arguments and inferences.

Multiple -conclusion logic extends formal logic by allowing arguments to have a set of conclusions instead of a single one, the truth lying somewhere among the conclusions if all the premises are true. The extension opens up interesting possibilities based on the symmetry between premises and conclusions, and can also be used to throw fresh light on the conventional logic and its limitations. This is a sustained study of the subject and is certain to stimulate further research. Part I reworks (...) the fundamental ideas of logic to take account of multiple conclusions, and investigates the connections between multiple - and single - conclusion calculi. Part II draws on graph theory to discuss the form and validity of arguments independently of particular logical systems. Part III contrasts the multiple - and the single - conclusion treatment of one and the same subject, using many-valued logic as the example; and Part IV shows how the methods of 'natural deduction' can be matched by direct proofs using multiple conclusions. (shrink)

The basic question of this monograph is: how should we go about judging arguments to be reasonable or unreasonable? Our concern will be with argument in a broad sense, with realistic arguments in natural language. The basic object will be to engage in a normative study of determining what factors, standards, or procedures should be adopted or appealed to in evaluating an argument as "good," "not-so-good," "open to criticism," "fallacious," and so forth. Hence our primary concern will be with the (...) problems of how to criticize an argument, and when a criticism is reasonably justified. (shrink)

Douglas N. Walton considers the question of whether the conventions of informal conversation can be articulated more precisely than they are at present. Specifically, he addresses the problem of the fallacy of ad hominem argumentation as it occurs in natural settings. Can rules be formulated to determine if criticisms of apparent hypocrisy in an argument are defensible or refutable? Walton suggests that they can, and ultimately defends the thesis that ad hominem reasoning is not fallacious per se. He carries his (...) analysis to the core of action--theoretic reasoning--by examining a number of specimen arguments. As suggested by the title, the conclusion of ad hominem argument is demonstrated to be relative to the arguer's position. In the appendixes of the book, articles by Gerald McAuliffe and Gordon R. Lowe illustrate vivid and powerful cases in which Walton's contentions are put to the test. (shrink)