Return to top of page. Exercises on Venn Diagram Use Venn diagrams to determine whether the grounds guarantee the claims in the following arguments. To do this, represent the grounds in the Venn diagram, then see if the diagram guarantees the claim. Only dragons breathe fire, and all dragons fly. So all flying dragons breathe fire.
Some sea creatures are mammals, and some mammals have well-developed social structures.
So some sea creatures have well-developed social structures. All flying mammals eat insects. Some mammals do not eat insects. So some mammals do not fly. Bats are flying mammals.