The Traditional Classification: Categorical and Conditional

In one line

Traditional logic divides propositions first into categorical, which assert without condition, and conditional, which assert only on a condition.

In the wording a student can write in an examination: a categorical proposition asserts a predicate of a subject absolutely and without any condition. A conditional proposition asserts a relation between two propositions, so that what it states is subject to a condition and neither part is asserted outright.

The basis of the division

MU also calls this Aristotle's classification, and a question asking for "Aristotle's classification of proposition" is asking for what this chapter and the next two contain. The scheme is his, and the traditional logic of Modules II and III is his logic, worked over by later writers.

The division is made on the manner of assertion, and that phrase is worth remembering because examiners ask for the basis and not only for the classes.

A categorical proposition asserts flatly. "All contracts are agreements." Nothing is held back and no condition is attached: it says that the predicate belongs to the subject, and that is the end of it.

A conditional proposition holds something back. "If the agreement is enforceable by law, it is a contract." Nothing is asserted about any actual agreement. What is asserted is a connection, and the parts stand or fall together.

The consequence, which is the whole practical point. From a categorical proposition you may argue immediately about the things it is about. From a conditional you may not, until you are told whether the condition holds. This is why sequence 40 said a conditional cannot by itself be an argument, and it is why so much legal drafting is conditional: a statute lays down what shall follow if certain facts exist, and says nothing at all about whether they do.

The four bases of the traditional classification

Added after the past-paper check. MU asks for the traditional classification "according to quantity, quality, relation, and modality", and it asks separately for analytic and synthetic propositions. The division into categorical and conditional above is the division by relation; the other three bases are here, so that a question printed in MU's own words can be answered as printed.

The traditional scheme classifies a proposition on four independent grounds. Each is a separate question about the same proposition, so every proposition has an answer under all four.

By quantity: universal or particular, settled by the quantifier. Sequence 280.

By quality: affirmative or negative, settled by the copula. Sequence 280.

By relation: categorical or conditional, settled by the manner of assertion, which is the division made in this chapter. Some writers subdivide the conditional into hypothetical and disjunctive at this level rather than the next.