For each of the following arguments, state whether the indicated changes would make the argument weaker or stronger, and explain why. The strength of the argument might not be affected at all. If so, say why it is not affected.
1. My friend and I have seen many movies together, and we have always agreed on whether they are good or bad. My friend liked the movie trilogy The Lord of the Rings. So I probably will like it as well. Would this argument be weaker or stronger if:
a. The only movies that my friend and I have watched together are comedies, and The Lord of the Rings is not a comedy.
b. My friend and I have seen very many, very different movies together.
c. My friend and I always watched movies together on Wednesdays, but my friend watched The Lord of the Rings on a weekend.
d. The conclusion claims that I definitely will like The Lord of the Rings a lot.
e. The conclusion claims that I probably won’t totally dislike The Lord of the Rings.
2. All the students from Joe’s high school with high grades and high board scores did well in college. Joe also had high grades and board scores. So he will probably do well in college. Would this argument be weaker or stronger if:
a. The other students worked hard, but Joe’s good grades came easily to him, so he never learned to work hard.
b. Joe is going to a different college than the students with whom he is being compared.
c. Joe plans to major in some easy subject, but the other students were pre-med.
d. Joe recently started taking drugs on a regular basis.
e. Joe needs to work full-time to pay his college expenses, but the others had their expenses paid by their parents.
3. A new drug cures a serious disease in rats. Rats are similar to humans in many respects. Therefore, the drug will probably cure the same disease in humans. Would this argument be weaker or stronger if:
a. The disease affects the liver, and rat livers are very similar to human livers.
b. The drug does not cure this disease in cats.
c. The drug has to be injected into the rat’s tail to be effective (that is, it does not work if it is injected anywhere else in the rat).
d. No drug of this general type has been used on humans before.
e. The effects of the drug are enhanced by eating cooked foods.