Logical ReasoningDifficulty: Hard

PT140 S2 Q20 Explanation

Recent medical and anthropological

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

TopicsNecessary Assumption

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Stimulus

Recent medical and anthropological data show that prohibitions on the use of certain foods served important social, economic, and medical functions in ancient cultures. But these data cannot explain the origin of the prohibitions involved, since those who originally access to the same data as modern researchers.

What this question is testing

Necessary Assumption

Your task

Find the assumption the argument requires in order for its conclusion to hold.

Common trap

Answers that would help the argument but aren't strictly required (sufficient, not necessary).

Winning move

Negate each choice — the right one breaks the argument when negated.

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

The question
20.

Which one of the following is an assumption required by

Answer choices

  1. Correct66% picked this

    The origin of a food prohibition must be explained with reference to the understanding that the people who adopted

    Why this is right

    This answer sounds potentially too strong: must be explained. But, the author's conclusion justifies that strong wording, since she's saying "these data cannot explain the origin of the prohibitions". Let's consider her argument move, and then contrapose it: ppl who adopted and this data can't enforced taboos didn't → explain origins have access to this data of taboo The contrapositive would look like this, in order for data to explain the origin of a food prohibition, then the people who adopted and enforced the taboo must have had access to this data. That's essentially what this answer choice is saying, only instead of saying "access to this data", it's saying "an understanding of this data". If we negated this answer, would it weaken the argument? When explaining the origin of a food taboo, you don't need to consider the understanding of the people who adopted/enforced the taboo. That definitely weakens the argument, because it's saying that the Author's premise isn't really essential to the conclusion. The author is acting like, "this data can't possibly explain Y, because the people who created Y didn't know about the data". And this negation would be objecting, "We don't need to worry about whether or not the people who created Y understood the data in order to explain the origin."

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

  2. Out of Scope: Contradictory Prohibitions4% picked this

    The social, economic, and medical problems of a society may lead to the adoption of

    Nothing the author is saying has anything to do with a society's food prohibitions being internally contradictory.

  3. Out of Scope4% picked this

    The social importance of the origin of a food prohibition is independent of the nutritional value

    Out of Scope: Nutritional Value Unsupported Relationship Nothing the author says is talking about the nutritional value of foods, or relating it to social importance.

  4. Out of Scope: Forgotten6% picked this

    The original purpose of a food prohibition is often forgotten a few generations after the

    The author is never claiming that the original purpose was forgotten within 100 years of it being adopted. She's just saying that our modern data can't explain the original purpose of this ancient culture, because they didn't have access to our modern data.

  5. Too Strong: generally nontechnical20% picked this

    The people who originally adopted and enforced food prohibitions in ancient cultures generally had a nontechnical understanding of the

    This is the most tempting trap answer, for me. Our author is certainly assuming that these ancient cultures were more primitive than ours in terms of the sophistication of their data (her premise is that they wouldn't have had access to our fancy modern data). In fact, they may have had no data to go off of. It's too strong to say that the people creating and enforcing these taboos usually had a nontechnical understanding of the medical value of those prohibitions. The author is perfectly happy to believe that they had no understanding of the medical value of the prohibition. If anything, it sounds like our author is saying, "Great, you found a rationalization for their food taboo using modern medical data, but that can't be why they started the food taboo --- after all, they had no idea their food taboo had any medical benefit." If we negated this answer, we're saying "most of the time, the people who created a food taboo did not have a nontechnical understanding of the medical function of that taboo." That doesn't mean they did have a technical understanding. It could just mean they didn't have any understanding of the medical function. That would hurt the argument; it might even strengthen it.

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