An Online Resource for Logic Teachers and Students of Logic

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Strong and Weak

For each of the following inductive arguments, state whether it is strong or weak.

1 / 15

Sandra’s math teacher says that God exists. Thus God probably exists.

2 / 15

Different cultures have different beliefs about morality. Thus there is no objective basis outside of cultural norms for any moral claim.

3 / 15

People try on shoes before buying them. People drive cars before signing up for a three-year lease. People take a close look at travel information before committing to an expensive vacation. Thus people should have sex with each other before committing to marriage.

4 / 15

It has rained every day in the Darién Gap for the past twenty-five years. Thus it will probably rain in the Darién Gap tomorrow.

5 / 15

Serious biologists will tell you that mice are mammals. Thus mice are mammals.

6 / 15

Upon landing at the airport, passengers saw buildings that had toppled over, large cracks deep in the earth in the runway, fire engines running about, and paramedics assisting injured people. A geologist on board said it looked like an earthquake scene. The passengers concluded that an earthquake probably just occurred.

7 / 15

Paul has eaten at Joe’s Café once before for breakfast, and liked the food. On that basis, Paul concludes that he will love the food at Joe’s Café tonight when he goes there for dinner.

8 / 15

Hakim has eaten at Joe’s Café every day for two weeks, and has liked the food each time. Hakim plans to go to Joe’s Café tonight for dinner, and on the basis of his past experiences concludes that he will likely enjoy this meal, too.

9 / 15

A reliable study showed that 90 percent of the university’s students want better food in the school cafeteria. Latisha is a student at the university. It follows that Latisha probably wants better food at the cafeteria.

10 / 15

Two teenagers were found writing graffiti on the school walls yesterday. Thus all teenagers are delinquents.

11 / 15

Ranger Dan has listened to the elderly woman’s strident complaint about beach nudity. Ranger Dan has also listened to over a dozen nudists shout their points of view regarding the elderly woman’s’ complaint. Ranger Dan works under an incompetent site administrator who demands that Dan resolve all beach user-conflict quickly and in such a way that avoids negative media attention. Thus Ranger Dan is probably feeling frustrated.

12 / 15

A spokeswoman for the nude sunbathers at the officially sanctioned clothing-optional beach plans to politely explain to the elderly woman complainant that no one at the beach had broken any law. Therefore it is likely that this particular elderly woman will subsequently and happily join the nudists for a game of Frisbee on the beach.

13 / 15

An elderly lady drove 50 miles out of her way to visit the officially sanctioned clothing-optional beach at the state park, and complained to the park ranger there that she was offended by the nudity she saw through her binoculars. Thus the ranger should arrest every nude sunbather at the beach for disorderly conduct.

14 / 15

An official state parks sign at a beach says, “Attention: Beyond this point you may encounter nude sunbathers.” Therefore the beach in front of you is probably sanctioned for clothing-optional use.

15 / 15

A box contains 1000 U.S. coins. Two selected at random were one cent pennies. Thus the entire box probably contains nothing but pennies.

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The average score is 86%