Categorical Logic and The Venn Test of Validity for Immediate Categorical Inferences
Completion requirements
Read these sections to learn and apply a visual method for determining the validity of categorical inferences: Venn diagrams. Note the four categorical forms and what they mean: universal affirmative, universal negative, particular affirmative, and particular negative. Get comfortable drawing Venn diagrams for categorical statements and shading in the area or drawing a star for the statements you are given.
Complete the exercises, checking your answers against the answer keys, translating the diagrams into statements, and using the Venn test of validity to determine the validity of the given categorical inferences.
Exercise
Apply the Venn test of validity in order to determine
whether the following categorical inferences are valid or invalid.
- All S are P; therefore, all P are S
- Some S are P; therefore, some P are S
- Some S are P; therefore, some P are not S
- Some S are P; therefore, all P are S
- No S are P; therefore, no P are S
- No P are S; therefore, some S are P
- Some S are not P; therefore, some P are not S
- All S are P; therefore some P are not S