Logical ReasoningDifficulty: Hard

PT123 S3 Q17 Explanation

When exercising the muscles in one’s back

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

TopicsNecessary Assumption

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Stimulus

When exercising the muscles in one’s back, it is important, in order to maintain a healthy back, to exercise the muscles on opposite sides of the spine equally. After all, balanced muscle development is needed to maintain a healthy back, since the muscles on opposite sides of the keep the back in proper alignment and protect the spine.

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
17.

Which one of the following is an assumption required by

Answer choices

  1. Too Weak17% picked this

    Muscles on opposite sides of the spine that are equally well developed will be enough to keep the

    This implies that a HB ? BMD healthy back requires BMD ? EOS that the muscles on PA ? PE opposite sides of the spine pull equally.

  2. Correct58% picked this

    Exercising the muscles on opposite sides of the spine unequally tends to lead to

    Why this is right

    This bridges the gap between balanced muscle development and exercising the muscles on opposite sides of the spine equally.

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

  3. Reversal22% picked this

    Provided that one exercises the muscles on opposite sides of the spine equally, one will have

    This reverses the EOS ? HB conclusion of the argument.

  4. Too Strong2% picked this

    If the muscles on opposite sides of the spine are exercised unequally, one’s back will

    While this provides a ~EOS ? ID relationship similar to the conclusion, it goes too far. It need not be the case that the back is irreparably damaged in order for it to be unhealthy.

  5. Out of Scope1% picked this

    One should exercise daily to ensure that the muscles on opposite sides of the spine keep the

    The frequency of one’s exercises is not relevant to this argument.

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