There are two kinds of logic: 1. Syllogistic. 2. Criterional. How any one
can by any spinning make out more than ten or a dozen pages about the
first, is inconceivable to me; all those absurd forms of syllogisms are one
half pure sophisms, and the other half mere forms of rhetoric.
All syllogistic logic is--1. _Se_clusion; 2. _In_clusion; 3. _Con_clusion;
which answer to the understanding, the experience, and the reason. The
first says, this _ought_ to be; the second adds, this _is_; and the last
pronounces, this must be so. The criterional logic, or logic of premisses,
is, of course, much the most important; and it has never yet been treated.
* * * * *
The object of rhetoric is persuasion,--of logic, conviction,--of grammar,
significancy. A fourth term is wanting, the rhematic, or logic of
sentences.
_September_ 24. 1830.