Term logic
Term logic, as used in the Logic Museum, covers the four main divisions of pre-Fregean logic, namely
- Aristotelian logic (the doctrines of Aristotle which are contained in the collection of his logical works known as the Organon)
- Scholastic logic (the logic taught during the 13th, 14th and 15th centuries in the Latin West)
- Traditional logic (the textbook tradition of logic lasting from the 16th century to the mid-19th century)
- Neo-scholastic logic (the presentation of logic found in textbooks written by neo-scholastics for the use of ecclesiastical seminaries and similar institutions)
Division of term logic
According to the theory underlying term logic, our understanding has three components, namely terms, propositions and arguments. Terms are simple parts of speech. Propositions and arguments are complex, propositions being built from terms, and arguments from propositions.
A term is a part of speech representing something, but which is not true or false in its own right, such as 'man' or 'mortal'.
A proposition, usually understood as a categorical proposition, is composed of just two terms, plus a copula – hence the name 'two-term theory' or 'term logic'. One term (the 'predicate') is 'affirmed' or 'denied' of the other (the 'subject'). Propositions, unlike terms, are capable of truth or falsity because of affirmation and denial.
Finally, the syllogism is an inference in which one proposition (the 'conclusion') follows of necessity from two others (the 'premises').
Systems of term logic
Term logic is wider than modern logic. Modern logic corresponds mostly to the third operation of the understanding, namely argumentation. Term logic covers the first two as well. The first operation is the subject of Aristotle's Categories (as well as to his later Metaphysics, a comprehensive, as well as difficult, discussion of what terms signify). The second operation is the subject of his De Interpretatione, which discusses his conception of proposition and judgment, and the various relations between affirmative, negative, universal, and particular propositions. This part is closely connected with what we now call 'philosophy of language'.
The third operation is the subject of two books by Aristotle, namely the Prior Analytics and the Posterior Analytics. The first deals with the theory of the syllogism, the second with Aristotle's theory of scientific demonstration.
Two other books by Aristotle also discuss argumentation, namely the Topics and Sophistical Refutations. Medieval systems of logic closely follow Aristotle's system of division and ordering. See e.g. Ockham's system as presented in his Summa Logicae.
Scholastic systems of logic
In approximate date order:
- Summulae Dialectices (Roger Bacon)
- Summa Totius Logicae (Anon)
- Summa Logicae (Ockham)
- Summulae de dialectica (Buridan)
