Free LSAT Course > Logical Reasoning > Modify Arguments

In the last few chapters, you have learned how to examine the structure of arguments, find flaws in reasoning, and identify the principles underlying specific statements and questions on the LSAT. In this chapter, we’re going to be doing even more complex tasks: fixing and/or weakening arguments. For most students, this is typically the most difficult portion of the Logical Reasoning aspect of this course. Please proceed slowly and do not hesitate to read and reread these sections as many times as possible before moving on to the practice questions.

CHALLENGE: Strengthen Key Assumptions

Strengthen Questions ask you to find statements that increase (strengthen) or decrease (weaken) your belief in the argument. Since the premises are taken to be true, the way to increase or decrease the belief in an argument is to increase or decrease belief in the assumptions of the argument.

Please remember that a strengthen correct option choice will not make the argument fool-proof; it’ll just make the argument stronger. Similarly, a weaken correct choice will not demolish the argument completely; it’ll just make it weaker to some extent.

Here are some examples of Strengthen Question stems (note that when it says “if true”, it means that you must accept the validity of the statement):

  • The conclusion would be more properly drawn if it were made clear that . . .
  • Which of the following, if true, would most strengthen the conclusion drawn in the passage above?
  • The argument, as it is presented in the passage above, would be most strengthened if which of the following were true?
  • Which of the following would most strongly support the author? Note: that isn’t a typo. The most strongly support is actually asking you which option would strengthen the argument (not a Most Strongly Supported).

Intro (0:01) | Ex.1 (2:25) | Ex.2 (8:29) | Ex.3 (13:49) | Trap Choices (18:27)
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Tips for Strengthen 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 either going to weaken or strengthen 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.
Critical Reasoning Strengthening and Weakening Arguments

Use strong language to weaken or strengthen. On most other Logical Reasoning questions, you can eliminate potential answers that use strong language. The exception is 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.

Sweeping Generalizations and Weasel Words

  • All sweeping statements should be noticed.
  • Always notice sweeping statements.
  • Never ignore sweeping keywords.
  • None of these keywords should be ignored.
  • Only ignore sweeping statements at your peril.

Sweeping statements take just a single exception to disprove the argument. However, if it is in the stimulus (the question text) or a rule in Logic Games, then these are very useful because they are so forceful.

Qualifiers make arguments easier to defend:

  • Some people call qualifiers “weasel words”.
  • Sometimes even I make a mistake, so I use qualifiers.
  • Usually I like to play it safe and am too scared to make statements without qualifiers.
  • The sun will probably rise tomorrow.

These words soften an argument and make it harder to refute because they can withstand some exceptions. Of course, they also water down the strength of statements.

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