Logical ReasoningDifficulty: Hard

PT131 S3 Q19 Explanation

If understanding a word always

A free, expert breakdown of this official LSAT Logical Reasoning question.

TopicsMust be True

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Stimulus

If understanding a word always involves knowing its dictionary definition, then understanding a word requires understanding the words that occur in that definition. But clearly there are people—for example, all babies—who do some of the words they utter.

What this question is testing

Must be True

Your task

Break the argument into its conclusion and evidence, then do exactly what the question stem asks with that structure.

Common trap

Answers that sound relevant to the topic but don't connect to the argument's actual reasoning.

Winning move

Predict what a right answer must do, then test each choice against the conclusion-evidence gap.

Reading along? Open the full official question in LawHub — we show a fragment here and keep the reasoning in our own words.

The question
19.

Which one of the following statements follows logically from the

Answer choices

  1. Unsupported Relationship36% picked this

    Some babies utter individual words that they do

    This assumes that B ↢some↣ ~UW (UW → KD) is true. Since it is not known whether it is true, that babies do not know the dictionary definitions of some of the words they utter does not establish that babies do not understand some of the words that they utter.

  2. Unsupported Relationship6% picked this

    Any number of people can understand some words without knowing their

    This would be UW → KD implied if it were known that (UW → UWD) is not true.

  3. Too Strong10% picked this

    If some words can be understood without knowing their dictionary definitions, then babies

    If some words can be understood without knowing their dictionary definition, then it could be that babies understand some words, but to say that babies do understand some words goes too far.

  4. Negation8% picked this

    If it is possible to understand a word without knowing its dictionary definition, then it is possible to understand a word without

    This negates the (UW → KD) → (UW → UWD) first statement.

  5. Correct40% picked this

    If some babies understand all the words they utter, then understanding a word does not always involve

    Why this is right

    Babies do not know the B ↢some↣ ~KD dictionary definitions of some of the words they utter. Babies understand all B → UW of the words they utter. Together, these two statements establish that understanding doesn't require knowing the dictionary definition, because together they would show that babies can understand even though they don't know dictionary definitions.

    Skill tested: Must be True · how this choice captures the argument's function is the move to repeat next time.

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