文档介绍：Logic
To appear in L. Floridi (ed.), The Blackwell Guide to
the Philosophy puting and Information
G. Aldo Antonelli
Dept. of Logic & Philosophy of Science
University of California, Irvine
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November 2001
1 Origins of the modern conception of logic
Logic is an ancient discipline that, ever since its inception some 2500 years
ago, has been concerned with the analysis of patterns of valid reasoning.
Aristotle first developed the theory of the syllogism (a valid argument form
involving predicates and quantifiers), and later the Stoics singled out patterns
of propositional argumentation (involving sentential connectives). The study
of logic flourished in ancient times and during the middle ages, when logic
was regarded, together with grammar and rhetoric (the other two disciplines
of the trivium) as the foundation of humanistic education.
Throughout its history, logic has always had a prescriptive as well as a
ponent. As a descriptive discipline, logic aims to capture the
arguments accepted as valid in everyday linguistic practice. But this aspect,
although present throughout the history of the field, has since the inception
of the modern conception of logic, some 100 or 150 years ago, taken up a
position more in the background, and in fact some have argued that it is not
any more part of logic proper, but belongs to other disciplines (linguistics,
psychology, or what have you). Nowadays logic is, first and foremost, a
prescriptive discipline, concerned with the identification and justification of
valid inference forms.
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The articulation of logic as a prescriptive discipline is, ideally, a two-fold
task. The first task requires the identification of a class of valid arguments.
The class thus identified must have certain features: not just any class of
arguments will do. For instance, it is reasonable to require that the class of
valid argument be cl