An Online Resource for Logic Teachers and Students of Logic

Share on facebook
Share on twitter
Share on linkedin
Share on email

0%
1

Soundness and Cogency

For each of the following arguments, determine three things: (a) whether it is deductive or inductive, (b) whether it is valid or invalid (if deductive), or strong or weak (if inductive), and (c) whether it is deductively sound or unsound (if deductive), or cogent or uncogent (if inductive).

1 / 15

India is north of the Antarctic. It follows that the Antarctic is south of India.

2 / 15

Mexico City’s human population is today well over 1000. Thus it is guaranteed that the human population today of Mexico City is over 500.

3 / 15

No human has ever swum across the Atlantic Ocean. The president of the USA is a human. Thus the president of the USA will likely not swim across the Atlantic Ocean.

4 / 15

Paris is in France, and France is in Africa. Hence it must be the case that Paris is in Africa.

5 / 15

All rats are mammals, and no mammals are fish. Thus it is necessary that no rats are fish.

6 / 15

Thinkers have yet to agree on an absolute or objective basis for morality. Thus it is certain that there is no absolute or objective basis for morality.

7 / 15

Our moral beliefs are produced through environmental conditioning. Thus is highly likely that there is nothing absolute or objective about morality.

8 / 15

Different cultures have different beliefs about morality. Thus it is certain that there is nothing absolute or objective about morality.

9 / 15

Highly respected physicists say that it is important to learn math in order to excel at advanced physics. Thus it is important to learn math to excel at advanced physics.

10 / 15

Beijing—the capitol of China—is a large, famous, and interesting city. Thus Beijing probably receives at most a dozen tourists a year.

11 / 15

Ethiopia is north of Kenya, and Kenya is north of Botswana. Therefore it is guaranteed that Ethiopia is (at least in part) north of Botswana.

12 / 15

The capitol of Costa Rica is San Jose. The capitol of Panama is Panama City. Most of Costa Rica is north of Panama. Thus it is certain that San Jose is north of Panama City.

13 / 15

In 1950, basketball star Michael Jordan was president of Argentina. All basketball players are athletes. Thus in 1950, Argentina had an athlete as president.

14 / 15

The USA has never elected a woman as president of the country. Thus in the next election, the USA will likely elect a woman as president of the country.

15 / 15

It has never snowed in the mountains of Tibet. Thus it will not likely snow there this year.

Your score is

The average score is 0%

0%