Logical Reasoning

PT124 · S2 · Q8 Travel writer: A vacationer should

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

  • Save & drill this skill — build targeted practice sets from questions like this one

  • Video walkthroughs — watch every question solved step by step

  • 81 official LSATs — as questions, timed sections & full-length tests

Start practicing free

Travel writer: A vacationer should choose an airline that has had an accident in the past 5 years.

Main Conclusion (should = opinion)

A vacationer should choose an airline that has had an accident in the past 5 years.

Conclusion (So)

If an airline has had no accident during the past 5 years, the chances that the airline will have a crash are increased.

Evidence

The average airline has 1 accident every 5 years.

Evaluate

Since there are two conclusions drawn, we're technically accountable for evaluating both reasoning moves.

Given that ... the average airline has 1 accident every 5 years, Should we accept that ... if an airline hasn't had an accident during the past 5 years, the chances they will have a crash are increased?

No, that's called the Gambler's Fallacy. If you're flipping a coin with your buddy, and it's heads, does that mean the next flip is more likely to be tails?

No, it's a 50/50 "coin flip" every time.

What if the last five flips were all Heads? Doesn't that make it more likely that the next flip is Tails?

No. The past has no causal influence on the probability of your next coin flip.

Another potential issue we could raise is the idea of "the average airline". Let's say we were trying to figure out how many accidents airlines have on average over a 5 year span.

Last 5 years Jet Blue: 0 accidents Virgin: 0 accidents Spirit: 3 accidents Southwest: 1 accidents

Dividing those 4 accidents by 4 airlines we'd get that . Does that mean that we should avoid JetBlue or Virgin because they didn't have any accidents? Shouldn't we maybe trust them more when it comes to safety because they didn't have any accidents?

Okay, what about the 2nd reasoning move:

Given that ... an airline that's had an accident in the last five years has a lower chance of having a crash, Should we accept that ... a vacationer should choose such an airline?

Maybe there are other factors that go into how a vacationer should choose an airline. Sure, "risk of crash" is one. But price / convenience / in-flight amenities and such could also be relevant concerns.

Goal

It's probably more likely they'll test the Gambler's Fallacy flaw involved in reaching the Intermediate Conclusion, since that error occurs farther upstream and keeps the 2nd move to the Main Conclusion from even being relevant to critique.

But let's look for an answer that either interprets probability or averages too literally, thinking that past data points somehow alter the probability of something occurring. (Or find an answer where someone is making a recommendation based on that option having one advantage, when it's possible that other options have different advantages that outweigh this option's stated advantage).

8.

The flawed reasoning in the travel writer's argument is most similar to that in which one of the following arguments?

  1. A tossed coin has come

    Reasonable Logic

    While this is tempting because we're primed to look for the Gambler's Fallacy, and the "coin flip" is the classic example used to illustrate it. But this argument makes sense. It's astronomically unlikely that a fair coin would come up heads 100 times in a row, so while that wouldn't 100% prove it's not a fair coin, it would certainly support a very reasonable suspicion that it's not a fair coin.

    3% picked this

  2. Correct

    If there are 10 adult

    Why this is right

    This only mimics the move from Premise to Intermediate Conclusion (it has no 2nd conclusion), but as we suspected, that is the main error LSAT wants us to catch. This answer, like the original argument, interprets average rates too literally and thinks that past data points influence future probability. The idea of Gambler's Fallacy is that because the probability of tails is 1/2, if you get heads a few times in a row, you feel overdue for some tails. That's an incorrect understanding of probability, though, which balances out to 1/2 over an infinite time scale. In this argument the author is acting like an adult male that hasn't ascended to dominance over the past 10 years is now overdue to ascend to dominance. What do we mean by "interpreting probability too literally"? If I have a six-sided die, the probability of rolling a 4 is 1/6. Rolling a 4 is one of six possible outcomes, so it has a 1/6 probability. Does that mean that if I roll a die six times, I'm guaranteed to get exactly one 4? Of course not. But that's how the author is thinking about probability. If the average rate of airline accidents is 1 every 5 years, then over any 5 year time span, an airline should have exactly 1 accident. If a baboon has a 1/10 probability of ascending to dominance, then over any 10 year time span, that baboon should have ascended to dominance exactly once.

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

    86% picked this

  3. On a given day, an

    Different Flaw

    This argument is attempting to apply a probability statistic to an individual, but it's unclear whether the statistic can be properly applied to that individual. If I say, "the chance that an NFL player is left-handed is 1 in 8. Thus, Marty, an NFL player, has a 1 in 8 chance of being left-handed", that would be a reasonable application of a statistic. But this probability statistic is about "average resident", and it's not clear that a 5-year old would really constitute an average resident (5-year olds might not be in cars nearly as much as other age groups). If we accept that Marty qualifies as an average resident, then there is no flaw. If we think that Marty doesn't qualify as an average resident, then that's a different flaw from the original.

    4% picked this

  4. The average adolescent who works

    Different Flaw

    This is a flawed argument, but it's not committing a Gambler's Fallacy, it's just doing an inappropriate comparison and basically failing to consider how weighted averages might ruin its conclusion. The argument establishes a three part inequality: part-time < full-time < full-time adolesc adolesc adult We know that the full-time adolescents make an average of 76% of what the full-time adults do. And we know part-time adolescents make even less. So it would be a valid conclusion to think that "the average adolescent who works part-time makes less than 76 cents for every dollar made by a full-time employed adult". But since the conclusion just says "employed adult", it includes part-time and full-time adults. We don't have any information about what part-time adults make. Even though it would go against our common sense, it's possible that part-time adults make less than part-time adolescents. part-time < part-time < full-time < full-time adult adolesc adolesc adult We would know that part-time adolesc make less than 76% of full-time adults, but in this inequality they make more than 100% of part-time adults. So if you compared what part-time adolescents make to what all employed adults make, the % would be something higher than 76%. You don't need them to make MORE money for this conclusion to be wrong. If part-time adolescents make 100% what part-time adults make (i.e. they get paid the same), that would also ruin the conclusion. It would still mean that part-time adolescents make more than 76% of what all employed adults make (the percentage would be a weighted average between 76% and 100%, based on what share of employed adults work part-time vs. full-time).

    1% picked this

  5. Though until recently this chess

    Weak Match

    This argument does treat probability literally, in a way. It thinks that if this master has been responding with Y 90% of the time, then he's 90% likely to respond with Y in the next instance. This is different in an important way, though: In both the original argument and in the correct answer, the author is looking at an average rate for X occurring and thinking that someone is overdue for X and so their probability of X is now higher than before. In this argument, the author thinks the probability of Y occurring on the next move will be the same as it's been for previous instances in this tournament.

    6% picked this

Continue the review in LSAT Lab

Save this question, watch the video walkthrough, and drill similar questions in your LSAT Lab account.

Save and practice this skill
LSAT Lab

Turn this review into a targeted study plan.

Save this question, drill more like it, watch the video walkthrough, and track your progress in your LSAT Lab account.

Start practicing free