Diagrammatic Representation of Categorical Propositions in Experimental Research

Propositions otherwise expressed in words can also be picturized, using circles to represent classes; some of the symbolic representa­tions in traditional logic and their literal meanings are shown in Figure 13.2.

A categorical proposition, having to refer to two classes, one each for the subject term and the predicate term, requires two cir­cles for symbolic representation (see Figure 13.3).

Based on these symbolisms, the four standard categorical propositions, each traditionally symbolized by one of the four capitol letters, A, E, I, O, can be represented as shown in Figure 13.4. Named after the English logician John Venn (1834—1923), these and similar representation are known as Venn diagrams.

Source: Srinagesh K (2005), The Principles of Experimental Research, Butterworth-Heinemann; 1st edition.