Self-study
Support Using rational argument in advertisements does not persuade people to buy the products being advertised. ██████████ ███████████ ███ ███████ ████████ ████████ ████ ███████████ ███████ ██ ███████ ██ ██████████████ ████ ████████ ██████ ██ ███ ███ ████████ █████ ███████████
Method of Reasoning
The author concludes that nonrational, emotional appeals will succeed in advertising. His reasoning is that rational arguments do not succeed.
Identify and Describe Flaw
The author observes that a sufficient condition (using rational argument) triggers a necessary condition (failed advertising). He then assumes he can negate both conditions: not using rational argument leads to successful advertising. But negating both sides of a conditional statement is not automatically valid. Here, it’s still possible that the nonrational emotional appeals are also unsuccessful advertisements.
Consider the analogous flawed argument: if it’s an apple, it’s edible. Therefore, if it’s not an apple (e.g. if it’s a grape), it’s inedible.
13.
Which one of the following ████████ ██████ █████████ ████ ███████ ██ ███ ██████ █████████ ██ ███ ████████ ██████
a
People who ask ██████ ███ ██████ ███ ████████ ██████████ ██████ ███ ███ ███ ███ ███ ██████████ ██ █████ ███████ ███ █████ █████ ███ █ ██████
This is a valid argument, unlike the stimulus. (A) uses a valid contrapositive: it switches the initial relationship (if you ask for favors, you are refused) and negates both sides. By contrast, the stimulus negates both sides of the relationship, but doesn’t switch them.
b
In the past, ██████ ███ ████ █████ ██ █████ █████ ████████ ██ ██████████ ████ ████ █████ ███████ ██████████ ██ ███ ███████ ██████ ███ ███ ██ █████ █████ ████████ ██ ██████████ ████ ████ █████ █████
This is a different flaw. (B) assumes that, because something was true in the past, it must be true in the future. By contrast, the stimulus mistakenly assumes that a negation of both sides of a conditional relationship is valid.
c
Using a computer ███ ███ ████████ █████████ ███████ ███████ █████ ████████ ██████ ███ ███ ██ ███████ █████ ███████ ██████ ██ █████ █ █████████
If this is a flawed argument, it’s not the same flaw as the stimulus. The conclusion of (C) is an “ought” statement: students should not try to improve their skills. By contrast, the stimulus’ conclusion is an “is” statement: nonrational, emotional appeals will persuade people.
d
A person who ████ ███ ████ ████████ ███████ ██ █████████ ██████ ███ █ ████ ████ ██████████ ███ ██████ ███ ███████ ██ █████████ █ ██████ ████ ███ ██████ ███ ███ ████ ██████ ████ ████
This is the wrong flaw. (D) mistakenly assumes that increasing a necessary condition must increase a sufficient condition. An analogous argument would be: If you don’t eat food, you will die. Therefore, the more food you eat, the longer you’ll live. By contrast, the stimulus mistakenly assumes that a conditional statement is still valid when both sides are negated.
(D) would be correct if the conclusion were: “Therefore, a person who does have positive letters of reference will get a good job.”
e
People never learn ██ ███████ █ ████████ ██ ███████ ██████ ███████ ███████████ ██████████ ██ ██████ ████ ████████████ ███████████ ████ ████ █████ ██ ███████ █ █████████
(E) concludes that, if people read well-written directions, they will learn to program a computer. This is because, if people don’t read well-written directions, they won’t learn how to program a computer. This is the same flaw as the stimulus: assuming that a conditional statement is still valid after negating both sides. In this case, it’s possible that people who read well-read directions are still unable to program.