MAT 144 Week 1 Discussion 2
A deductive argument is valid if the conclusion necessarily follows from the premises. It is sound if it is valid and the premises are true.
Pick three of the following arguments and clearly explain why each argument is or is not valid or sound.
- 1. No human lives in outer space. Susie lives in outer space. Thus, Susie is not human.
- 2. All birds can fly. Ostriches are birds. Therefore, ostriches can fly.
- 3. All jobs are easy. Walking is not a job. Hence, walking is not easy.
- 4. When it rains, it snows. It is snowing. Therefore, it is raining.
- 5. No dog is a cat. Billy is a cat. Thus, Billy is not a dog.
- 6. If someone is a medical doctor, they are smart. Dr. Oz is a medical doctor. So, Dr. Oz is smart.
- 7. Whichever candidate receives the greatest share of the popular vote is elected President of the United States. Al Gore received more votes than George Bush. Therefore, Al Gore was elected President of the United States.