Using Venn Diagrams


Categorical syllogisms are the oldest form of argument to be treated in a formal, systematic way. Venn diagrams, invented in 1880 by John Venn, are a handy way of graphically representing the formal structure of categorical syllogisms and testing them for validity.

For this discussion, create Venn diagrams for the following arguments, indicating whether each diagram shows the argument to be valid or invalid. Hint: at least one of them is valid and at least one is invalid.

There are some Venn diagram makers available on the Internet. Use a Power-Point to show the illustration of the Venn diagrams in relation to the questions below:

  1. All hospitals are health care centers.
    • Some health care centers are not profit-driven institutions.
    • Therefore, some hospitals are not profit-driven institutions.
  2. No tigers are herbivores.
    • No herbivores are malevolent.
    • Therefore, all tigers are malevolent.
  3. Some disasters are catastrophes.
    • Some disasters are really unpleasant events.
    • Therefore, some catastrophes are really unpleasant events.
  4. All venture capitalists are risk-takers.
    • Some risk-takers are wealthy.
    • Therefore, some venture capitalists are wealthy.
  5. All Aristotelians are metaphysicians.
    • No positivists are metaphysicians.
    • Therefore, no positivists are Aristotelians.

Additional Instructions:

Create a Power-Point to show the illustration of the Venn diagrams in relation to the questions: Use as many slides as needed. Keep the format structure of APA. Use sources as needed.