From Fogelin, R. J./W. Sinnott-Armstrong (2005) Critical Reasoning, 7^th ed., Wadsworth.  

Exercise I, p. 253

Assuming a standard context, label each of the following arguments as deductive or inductive. Explain what it is about the words or the form of argument that indicates whether or not each argument is intended or claimed to be valid.

1.                    The sun is coming out, so the rain will probably stop soon.

2.                    It’s going to rain tomorrow, so it will either rain or be clear tomorrow.

3.                    No woman has ever been elected president. Therefore no woman will ever be elected president.

4.                    Diet cola never keeps me awake at night. I know because I drank it just last night without any problems.

5.                    The house is a mess, so Jeff must be home from college.

6.                    If Harold were innocent, he would not go into hiding. Since he is in hiding, he must not be innocent.

7.                    Nobody in Paris seems to understand me, so either my French is rotten or Parisians are unfriendly.

Exercise II, p. 260

Give two competing hypotheses that might be offered to explain each of the following phenomena. Which of these hypotheses is better? Why?

1.                    You follow a recipe carefully, but the bread never rises.

2.                    Your house begins to shake so violently that pictures fall off your walls.

3.                    Your key will not open the door of your house.

4.                    People start putting television cameras on your lawn, and a man with a big smile comes walking up your driveway.

5.                    Virtually all of the food in markets has suddenly sold out.

6.                    You put on a shirt and notice that there is no pocket on the front like there used to be.

7.                    A cave is found containing the bones of both prehistoric humans and now-extinct predators.

8.                    A cave is found containing the bones of both prehistoric humans and now-extinct herbivores.

9.                    After being visited by lobbyists for cigarette producers, your senator votes in favour of tobacco price supports, although he opposed them before.

10.                 Large, mysterious patterns of flattened wheat appear in the fields of Britain. (Some people attribute these patterns to visitors from another planet.)

Exercise III, p. 261

For each of the following explanations, specify which standard of a good explanation, if any, it violates. The standards require that a good explanation be explanatory, deep, powerful, falsifiable, modest, simple, and conservative. A single explanation might violate more than one standard.

1.                    Although we usually have a class at this time in this room, I don’t see anybody in the classroom, because a wicked witch made them all invisible.

2.                    Although we usually have a class at this time in this room, I don’t see anybody in the classroom, because they all decided to skip class today.

3.                    Although we usually have a class at this time in this room, I don’t see anybody in the classroom, because it’s Columbus Day.

Exercise V, pp.267

For the following argument, 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 movies 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.