Week 3 Quiz

What makes an argument deductive, in this course's sense?

Select one.

• Its premises are meant to make the conclusion probable, as a forecast does.
• Its premises are meant to guarantee the conclusion, so true premises could not lead to a false one.
• Its premises succeed in proving the conclusion, so an argument that fails to prove anything cannot count as deductive.
• It moves from a general rule to a particular case, whatever its premises are meant to do.

Which statement gives the course's definition of a valid argument?

Select one.

• It is impossible for all its premises to be true and its conclusion false.
• All of its premises are true and its conclusion is true.
• Most people who read it would accept its conclusion.
• Its premises make its conclusion likely, though not certain.

True or false: a valid argument must have a true conclusion.

True or false.

• True
• False

A transit rider (illustrative) argues: "Every bus on this route is electric. The early bus runs on this route. So the early bus is electric." In fact, some buses on the route run on diesel, and the early bus is one of them. How should the argument be described?

Select one.

• Invalid, because its conclusion turned out to be false.
• Sound, because if its premises were true its conclusion would have to be true, and that is all soundness requires.
• Valid but not sound, because a false premise let a working link reach a false conclusion.
• Inductive, because it is about buses rather than about logic.

Which statement about inductive arguments matches this course's definitions?

Select one.

• A cogent argument cannot have a false conclusion, because all of its premises are true and its support is strong.
• Inductive strength is all-or-nothing, so an argument is either proved or worthless.
• A strong inductive argument becomes valid once enough premises are added.
• Strength comes in degrees, and even a cogent argument can have a false conclusion.

An argument (illustrative) reads: "If it rained overnight, the soccer field is wet. The soccer field is wet. So it rained overnight." Which case is a counterexample that shows the argument is invalid?

Select one.

• It rained overnight, and the soccer field is wet.
• The sprinklers ran overnight and it did not rain, and the soccer field is wet.
• It did not rain overnight, and the soccer field is dry.
• It rained overnight, but a tarp laid over the field the evening before kept the soccer field dry.

An argument (illustrative) reads: "If it rained overnight, the soccer field is wet. It rained overnight. So the soccer field is wet." What does the counterexample method show about it?

Select one.

• Valid, because no case makes both premises true and the field dry.
• It is invalid, because sprinklers could also wet the field.
• It is invalid, because on a dry morning its second premise is false.
• It is strong but not valid, because weather is never certain.

Read the running question's illustrative campus-newsletter passage: "The campus library should stay open around the clock during finals week. During finals week many students need a quiet, safe place to study late at night. The library is the only quiet, safe, well-lit study space on campus large enough to meet that need. Keeping the library open overnight for the five nights of finals week costs about 1,600 dollars in staff wages." In its map, the supplied premise P3 says the campus should provide study space students need during finals when it can do so at modest cost. Where does the arrow from P4, the 1,600-dollar staffing figure, point?

Select one.

• Straight at the conclusion, C, as a fourth independent reason.
• At P1, because the figure shows how many students need the library.
• At P3's "modest cost" condition, which the figure is offered to support.
• At the objection, because the figure answers it.

In the same running question, which support link is inductive?

Select one.

• The link from P1, P2, and P3 to C, because the course takes no side on whether the library should stay open.
• The link from P4 to the cost condition, since 1,600 dollars cannot guarantee "modest".
• Both links, because any argument about money is inductive.
• Neither link, because the 1,600-dollar figure is arithmetically correct.

The running question's map has 1 linked group (P1, P2, and P3) with one arrow to C, and 1 arrow from P4 to the cost condition. How many support links does the map have to test?

Select one.

• 4 links
• 1 link
• 5 links
• 2 links