Logical ReasoningDifficulty: Hard

PT154 S1 Q25 ExplanationEach major earthquake

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

TopicsParallel Flaw

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Stimulus

Each major earthquake in this region has been preceded by a series of minor tremors. Since the region has recently experienced a series of minor tremors, a region in the near future.

What this question is testing

Parallel Flaw

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
25.

Which one of the following arguments exhibits a pattern of questionable reasoning most similar to that exhibited by

Answer choices, explained

  1. Trap6% picked this

    In the past, a major hurricane has resulted from each tropical storm that formed in this region. Since no tropical storms are now forming

    Bad Premise Match Topic Match: natural disasters The first sentence doesn't seem to work as a match, because it's actually causal, "Hurricane resulted from Tropical Storm". In the original argument, the relationship was just temporal, "Each quake was preceded by tremors". Even if we forgave that, a matching structure would go on to say "Since we have seen tropical storms, there will be a hurricane".

  2. Weak Premise Match28% picked this

    This river has overflowed in every spring thaw following a winter with high snowfall. As this winter the area received a record amount of

    This is almost right, but this argument says: every time we've had x, y came after. x is happening. Thus y will happen. The original argument said: every time we've had x, y came before y is happening. Thus x will happen Original Argument This Answer before each quake after each snowy came tremors winter came flood the before (tremors) the before (snowy is happening winter) is happening ----------------------- ----------------------- the after (quake) the after (flood) will happen will happen

  3. Bad Premise Match5% picked this

    On planets other than Earth, the presence of certain rare minerals indicates that these planets experienced a period of heavy meteor bombardment. Since the

    There's no "every time X happened, Y came prior" premise to get us started. And the conclusion isn't making a certain prediction "it's stating a presumed similarity about the past". Let's bail.

  4. Bad Premise Match / Valid Logic8% picked this

    The introduction of non-native species to an island always results in the extinction of some of its native species. Since non-native species are currently

    I'm not getting past the first sentence of this one. It's causal again, like (A). introducing x always results in y If we do end up reading the whole thing, we also find out that it's a logically valid argument.

  5. Correct53% picked this

    So far, all local outbreaks of this disease among humans occurred soon after the detection of high infection rates among local wildlife. An unusually

    Why this is right

    This, just like the original argument, says: every time we've had x, y came before y is happening. Thus x will happen Original Argument This Answer before each quake before each outbreak came tremors came high infection the before (tremors) the before (high is happening infection) is happening ----------------------- ----------------------- the after (quake) the after (outbreak) will happen will happen

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

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