In the prior lesson, we discussed how to strengthen arguments. Weakening them is an identical process, but just in reverse.

CHALLENGE: Weaken Key Assumptions

Weaken questions ask you to find statements that decrease (weaken) the strength of an argument. Since the premises are taken to be true, the way to decrease the strength of an argument is to attack its assumptions that the argument relies upon. A weaken correct choice doesn’t need to demolish the argument completely; it’ll just make it significantly weaker.

Here are some examples of Weaken Argument question stems:

• Which of the following, if true, most seriously weakens the conclusion drawn above?
• Which of the following, if true, would provide the strongest evidence against the above?
• Which of the following, if true, casts the most serious doubt on the conclusion drawn above?

Tips for Weaken Questions:

1. Try to find one necessary assumption in the passage. This is what the right weaken answer will often target.
2. Causal fallacies (will be reviewed below) are very common on these questions. These questions typically try to say that A caused B. You are going to weaken that causal argument.
3. When you see a Weaken question that compares two things or tries to show them as similar, look for an underlying factor that makes such a comparison problematic.
4. There will likely be two or more choices that weaken the argument. In this case, re-read the passage carefully and see which one is most directly relevant to the premises, the conclusion, and the assumptions.
5. Common trap answer choices include:
   • A statement that strengthens (and doesn’t weaken) the assumptions and the overall argument. This is the opposite of what you want.
   • A statement with information not relevant to the argument.
   • A statement that requires additional facts to have value.

Use strong language to strengthen or weaken. On most other Verbal questions, you can eliminate potential answers that use strong language. The exceptions are the Strengthen/Weaken questions. On these questions, sweeping words are more effective:

• only
• the most
• extremely
• all

The reason? Extreme answers will have a more powerful weakening/strengthening effect on assumptions.

Example #1

In many pre-schools, children commonly tend to get colds before their resistance develops and the colds become much less frequent. It is clear that a child requires several colds before white blood cell concentrations rise high enough to effectively deal with colds.

Which of the following, if true, most seriously weakens this theory?

1. Parents stock up on cold medicine that alleviates the symptoms of a cold after a child gets sick.
2. There are many strains of the cold virus, and children develop resistance to individual strains.
3. White blood cells fight infection, and their production levels are stimulated by high infection levels.