Categorical proposition

The term categorical judgment (Latin categoria: basic statement ) (also: categorical proposition categorical statement ) is a term of the traditional, Aristotelian logic, in particular the syllogistic. In the categorical judgment of a class of objects is ( the subject, S) something ( the predicate, P, for example, a property ) by a copula attributed to or. Thus, the categorical judgment is an atomic statement, that is a statement that is not composed of other statements.

An example of a categorical judgment is the statement " All men are mortal "; here is the logical subject of the term " person" and the logical predicate of the term " mortal. " (The terms "subject" and " predicate " are in traditional logic with a different meaning as used in the grammar. )

The categorical judgment is on the one hand as opposed to composite statements ( in the traditional logic: hypothetical or disjunctive judgments, such as " if A, then B" or " A or B"), on the other hand, the modal statements with modalities such as possibility or necessity.

In the Aristotelian syllogistic is - in contrast to modern logic - made ​​generally to condition that expressions for subject and predicate are not empty ( example of an empty subject " unicorns "). This condition is called existential presupposition.

The four forms of judgment

Traditional logic assumes that each categorical judgment can be assigned to one of the following four types:

Quantity and quality

The property of a statement about how many items she speaks, is traditionally called the quantity of this statement. In this sense there is in the syllogism two quantities, namely, particular and universal. The property of a statement, a subject, a predicate to deny or, is traditionally called the quality of this statement. Speaks a statement to a subject a predicate, they are called affirmative statement, she speaks it from him negative decision. The types of statements are broken down in the following table according to their quality and quantity:

Examples

  • " The fungus is a spore plant" (type 1, A- judgment - Quantity: general, quality: affirmative)
  • " Whales are not fish " (type 2, E - judgment - Quantity: general, quality: negative )
  • "Some mammals are herbivores " (type 3, I- judgment - Quantity: particulate, Quality: affirmative)
  • " Most people are not Europeans " (type 4, O- judgment - Quantity: particulate, Quality: negative )

Contradictory, contrarian and subkonträre opposites, sub and super Alternation

Judgments of the four categories are specific conditions to each other:

A is (like E for O) a sufficient condition for I. I for A and O for E is a necessary condition.

Be graphically illustrates these relationships in a diagram, which has become known as the logical square ( see figure). The oldest known writing of the logical square dates from the second century AD and Apuleius attributed by Madauros.

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