Logical ReasoningDifficulty: Hard

PT114 S1 Q24 Explanation

One-year-olds ordinarily prefer

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

TopicsNecessary Assumption

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Full official LSAT questions are available through LawHub. This page provides LSAT Lab's explanation, strategy, and review tools without republishing the full official question.

Stimulus

One-year-olds ordinarily prefer the taste of sweet food to that of salty food. Yet if one feeds a one-year-old salty food rather than sweet food, then over a period of about a year he or she will develop a taste for the salty flavor and choose to eat salty food rather than by the type of food he or she has been exposed to.

What this question is testing

Necessary Assumption

Conclusion

The author wants to conclude: what you feed young kids actually changes their taste preferences.

Evidence

One-year-olds prefer sweet. Feed them salty for a year, and at age two they prefer salty.

Evaluate

Watch for the alternative explanation. The author treats the salty preference at age two as evidence that the salty exposure caused it. But there's another possibility: maybe two-year-olds just naturally prefer salty to sweet regardless of what they've been fed. If that's true, the experiment proves nothing — those kids would have preferred salty either way.

So the argument quietly assumes that two-year-olds don't naturally prefer salty to sweet. That's the alternative explanation it needs to rule out.

Goal

The right answer says: two-year-olds don't naturally prefer salty to sweet — only then does the experiment show that exposure changed the preference.

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

The question
24.

Which one of the following is an assumption required by

Answer choices

  1. Correct67% picked this

    Two-year-olds do not naturally prefer salty food to

    Why this is right

    This is the assumption the argument needs. The observed switch (kids preferring salty at age two after a year of salty food) only counts as exposure-driven change if two-year-olds don't naturally prefer salty to sweet anyway. If they did, the experiment's outcome would be explained by normal development, not by exposure. Negation test: suppose two-year-olds do naturally prefer salty to sweet. Then the salty preference at age two is just what we'd expect regardless of feeding history — and the argument's causal claim collapses. So the assumption is necessary.

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

  2. Bad Assumption16% picked this

    A child’s taste preferences usually change between age one and

    This says taste preferences usually change between ages one and two. The argument doesn't need this. The argument is about this specific group of children fed salty food — it claims their preferences changed because of exposure. Whether preferences usually change in the general population doesn't affect that claim. Not necessary.

  3. Bad Assumption11% picked this

    Two-year-olds do not naturally dislike salty food so much that they would not choose it

    This is a much weaker claim than (A). It says two-year-olds don't dislike salty so much that they wouldn't choose it over some other foods. But the argument's comparison is salty vs. sweet specifically. The argument doesn't need a claim about salty vs. "some other foods"; it needs a claim about salty vs. sweet. Negate this, and the argument's comparison is intact.

  4. Bad Assumption5% picked this

    The salty food fed to infants in order to change their taste preferences

    This adds a requirement about the food's palatability. The argument doesn't need the salty food to be pleasant — it just needs the kids to actually be fed it. The argument's mechanism (exposure-driven preference change) doesn't hinge on whether the experimental food is delicious; the kids are reportedly choosing salty over sweet at the end regardless. Not necessary.

  5. Out of Scope0% picked this

    Sweet food is better for infant development than is

    The argument doesn't make any claim about which food is better for development. It's about whether exposure affects preferences. Whether sweet is better for the child has no bearing on the causal claim about preference formation. Not necessary.

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