Logical ReasoningDifficulty: Easy

PT153 S2 Q13 Explanation

The use of ordinary dictionaries

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

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Stimulus

The use of ordinary dictionaries in interpreting the law is justified in the same way that chemists use the periodic table. The periodic table is a convenient source of agreed-upon background information that can be usefully applied to the problem on which a chemist is working. useful to a legal interpreter in resolving terminological issues.

What this question is testing

Weaken

Your task

Find the choice that makes the argument's conclusion less likely to be true.

Common trap

Answers that look negative but attack a claim the argument never relied on.

Winning move

Find the assumption the argument depends on, then pick the choice that undermines it.

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

The question
13.

Which one of the following, if true, most seriously weakens

Answer choices

  1. Weak Impact4% picked this

    The periodic table lists the properties of the elements, and presents them in a pattern to represent relations between them, while an ordinary dictionary

    This does point out some differences between the periodic table and an ordinary dictionary, and it does make the ordinary dictionary potentially seem less useful (because its organizational hierarchy isn't as rich in meaning). But it's a pretty mild attack. In order to argue that we can't use an ordinary dictionary to interpret law, we need to be able to say "you get bad information --- what it will tell you about a word like corporation isn't the legal meaning of that word". This is just saying that a dictionary doesn't do much to group words together into families that reflect relationships.

  2. Correct88% picked this

    There is wide agreement about the data on the periodic table, while disagreements between the definitions in different ordinary dictionaries are likely

    Why this is right

    This points to a difference between dictionaries and periodic tables, and the difference sounds meaningful when it comes to whether a legal interpreter should use an ordinary dictionary As the argument laid out the comparison, it says: Periodic table is 1. convenient source 2. agreed-upon background info 3. can be usefully applied to a chemistry problem Were we ever told that an ordinary dictionary was a convenient source of agreed-upon background info that can be usefully applied to a legal problem? No, and this answer is blowing up that assumed comparison. The periodic table is a standardized set of info that is widely agreed upon. But depending on which ordinary dictionary you're using, you might get a definition of a word that is not widely agreed upon and that is likely to impact the legal interpretation.

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

  3. No Impact1% picked this

    The use of a periodic table as a reference source actually came much later in history than the use of ordinary dictionaries

    This points to a difference, but not a meaningful one. We don't care when, in history, these things were invented. We only care if presently an ordinary dictionary is as useful to a legal interpreter as a periodic table is to a chemist. Not to mention, since ordinary dictionaries have the greater longevity in this answer choice, the comparison is somewhat flattering to ordinary dictionaries, which would be the opposite of our purposes.

  4. No Impact1% picked this

    The periodic table contains only a relatively small amount of information that could, in theory, be memorized, while the information in an ordinary dictionary

    This shows us a difference, but not a meaningful one. No one is expecting anyone to memorize the periodic table or an ordinary dictionary, so how easily each thing is to memorize is irrelevant. Both of them are reference materials, and we judge their usefulness primarily on whether they allow us to look up accurate info.

  5. No Impact6% picked this

    The periodic table is used primarily by chemists, while ordinary dictionaries are not used primarily by legal

    Like all the other answers, this did provide a distinction between the periodic table and ordinary dictionaries. But like the three other wrong answers, that distinction isn't one that gives us way to tell legal interpreters that they shouldn't use an ordinary dictionary. This problem essentially forced us to think about which distinction was most useful for arguing that "a legal interpreter shouldn't use an ordinary dictionary". Hey, lawyers, you shouldn't use an ordinary dictionary to resolve a terminological issue. After all, ... (A) they're organized alphabetically (B) depending on your dictionary you could get a definition that isn't agreed upon and likely is relevant to the legal interpretation (C) they were invented earlier than periodic tables were (D) they can't be memorized (E) they are used by non-legal professionals

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