Logical Reasoning

PT145 · S4 · Q25 Many conceptual categories are parts

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

Many conceptual categories are parts of dichotomous (distinct and mutually exclusive) pairs: good or bad, right or wrong, rational or irrational, etc. However, advances in scientific understanding have shown some long-held dichotomies to be untenable.

Conclusion (therefore)

Dichotomous classifications into mutually exclusive categories should generally be abandoned.

Evidence

Advances in scientific understanding have shown some long-held dichotomies to be untenable.

Evaluate

This doesn't quite seem like a Famous Flaw, unless we want to call it Sampling.

The main objectionable move seems to be that the evidence establishes that some dichotomies are untenable. But the conclusion is saying that we should generally abandon dichotomies.

Just because some of them are unwise, we should get rid of most of them?

Goal

Let's look for an argument that's saying something like,

25.

Which one of the following exhibits flawed reasoning most similar to that in the argument above?

  1. Review by outside consultants has

    Bad Evidence / Conclusion Match

    We wanted evidence about some and a conclusion about most (generally / typically / usually = most). Here we have evidence about replacing all computers and then a very weak conclusion about not all computers.

    2% picked this

  2. Correct

    Recent clinical trials have shown

    Why this is right

    We wanted an argument that felt like, "Since some X's are bad, X's should generally be abandoned." Here we have evidence saying some anti-anxiety drugs are bad (addictive / bad side effects), and a conclusion that is saying "anti-anxiety drugs should be discontinued". On a first pass, we would be wise to note that this conclusion is actually stronger than the conclusion in the original argument. A better match would be a conclusion that said, "anti-anxiety drugs should generally be abandoned". But ultimately, this answer is our best available match. It best replicates the flaw of, "Hey -- just because some X's are bad doesn't mean we need to give up on X's altogether". Just because some dichotomies have proven to be unwise doesn't mean we need to stop using all dichotomies. Just because some anti-anxiety drugs are bad doesn't mean we need to stop using all anti-anxiety drugs.

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

    81% picked this

  3. Current highway safety data clearly

    Bad Evidence Match

    We wanted evidence about some and a conclusion about most (generally / typically / usually = most). Here we have evidence saying that "all drunk drivers are dangerous", so we won't be able to replicate the same flaw of, "Hey -- just because some of them are bad doesn't mean that most/all of them are bad."

    2% picked this

  4. The longer fruit is kept,

    Bad Evidence / Conclusion Match

    We wanted evidence about some and a conclusion about most (generally / typically / usually = most). Here we have evidence giving us a Volume Dial type idea: the longer you've had fruit, the more likely it's rotten. Without a premise about Some, we won't be able to replicate the same flaw of, "Hey -- just because some of them are bad doesn't mean that most/all of them are bad." The flaw of this argument is more like, "Hey just because a peach you've had for a while is more likely to be rotten than one you've just got doesn't mean you should just ignore the evidence that these peaches seem to be fine."

    5% picked this

  5. This budget is based on

    Bad Evidence Match

    We wanted evidence about some and a conclusion about most (generally / typically / usually = most). Here we have evidence saying that "our past two years of data show that an assumption is unrealistic". So we won't be able to replicate the same flaw of, "Hey -- just because some of them are bad doesn't mean that most/all of them are bad." This argument actually doesn't seem very flawed. It seems like a pretty reasonable conclusion.

    11% 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