Logical Reasoning

PT112 · S3 · Q16 Herpetologist: Some psychologists attributecomplex

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

Herpetologist: Some psychologists attribute complex reasoning to reptiles, claiming that simple stimulus-response explanations of some reptiles’ behaviors, such as food gathering, cannot account for the complexity of such behavior.

Conclusion

Reptiles must be incapable of complex reasoning.

Evidence (since)

Experiments show that reptiles are incapable of making major alterations in their behavior.

Evaluate

The "but" signals that our author is rebutting the "some psychologists" in the first sentence. Hence, we don't necessarily need to care about what came before the 'but', other than for context or referential language.

The argument has only one premise (indicated by since). That "since" claim indicates that the other half of that sentence, the latter half, is the conclusion.

"Complex reasoning" is a New Concept in the Conclusion. If there's a new concept in the conclusion of an Assumption question, that concept is almost always in the correct answer.

We use all these indicator words to quickly suppress worrying about the first sentence and focus on the move from the first half of the last sentence to the second half:

since reptiles can't make major alterations in behavior we can conclude reptiles can't do complex reasoning

Goal

We should anticipate a Linking answer here. The author is making this move:

Can't make major → incapable of alterations in behavior complex reas.

We might want to also consider the contrapositive, since Linking answers are so frequently disguised that way:

Capable of → Can make major complex reasoning alterations in behav.

16.

Which one of the following is an assumption required by the herpetologist's argument?

  1. Animals could make major changes

    Illegal Negation

    The conditional indicators only if / only always indicates the necessary condition that goes on the right side of the arrow. (the only indicates a sufficient) So this is saying capable of major → capable of alterations in behavior complex reasoning That's an illegal negation of the argument, which went incapable of major → incapable of alterations in behavior complex reasoning Knowing our conditional logic is the easiest way to see this is a bad answer. Otherwise, we have to conversationally understand that in the original argument the author was assuming, "every thing that's capable of complex reasoning can make major alterations in its behavior", whereas this answer is saying "only things that are capable of complex reasoning can make major alterations in their behavior".

    20% picked this

  2. Simple stimulus-response explanations can in

    Too Strong

    Too Strong: all Doesn't Mention New Concept The fact that this doesn't mention "complex reasoning" means we wouldn't bother reading it if we were just scanning for the New Concept in the Conclusion. But if we do read it, we could say that the author definitely hasn't committed herself to what type of explanation can account for all reptile behaviors. This answer is trying the What Next? trap, where it baits students into thinking, "If the author believes their conclusion is true, what's the next thing the author might think on the basis of that"? Here's that's taking the form of thinking, "If someone believes it's true that reptiles are incapable of complex reasoning, then they probably believe that stimulus-response explains all reptile behavior." That's way too harsh a move. We don't have to assume that the only two ways to explain behavior are complex reasoning or stimulus-response.

    2% picked this

  3. Reptile behavior appears more complex

    Weakens Relative vs. Absolute

    If we were scanning for the New Concept in the Conclusion we might be tempted to give this the green light, since it mentions "complex". But we're looking for "complex reasoning", and this is saying "more complex behavior". That's not at all a match. If we actually read this answer, we'd see that it goes against the author's argument. The author never assumes something that goes against their argument. She's arguing that reptiles don't have complex reasoning, and this answer seems to be retorting, "Actually, reptile behavior is more complex than you think it is."

    0% picked this

  4. Correct

    If reptiles were capable of

    Why this is right

    The reasoning move from Premise to Conclusion was incapable of major → incapable of alterations in behavior complex reasoning By contrapositive, the author was thinking capable of → capable of major complex reasoning alterations in behavior This answer is saying exactly that. On harder questions where we're being tested on a Missing Link, we know that there are often illegal reversals / negations masquerading as the correct answer (and usually placed higher in the set of answers). Meanwhile, the correct answer is disguised in contrapositive form. That's why when we first articulate the "If Premise, then Conclusion" link we want, it's also beneficial to say the contrapositive version of that to ourselves as well.

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

    72% picked this

  5. Complex reasoning and responses to

    Too Strong: can't both contribute

    While ruling out language like "not" is very often part of correct answers on Necessary Assumption, if we negate this answer it doesn't weaken the argument, because it's speaking about a group of animals way broader than just reptiles. complex reasoning and responses to stimuli can both contribute to the same behavior The author is fine agreeing that there are times when complex reasoning and responses to stimuli combine. She would only say, "That's never the case with reptiles, since they don't have complex reasoning."

    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