Logical Reasoning

PT21 · S3 · Q8 Eva’s argument depends on the assumption

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

Eva: A “smart highway” system should be installed, one that would monitor areawide traffic patterns and communicate with computers in vehicles or with programmable highway signs to give drivers information about traffic congestion and alternate routes.

Conclusion (should)

A "smart highway" system should be installed.

Intermediate Conclusion (we can infer)

It would result in improved traffic flow in and around cities, improve drivers' tempers, and decrease the money and productivity we're currently losing to traffic.

Evidence

It would monitor local traffic patterns and warn drivers via radio or automated highway sign about where traffic sucks and where to go to avoid it.

Evaluate

This argument at its core seems to be a Plan with a Goal, so if we're trying to think of Assumptions / Objections, then we're asking ourselves , or asking ourselves

With most Plans, the authors need to assume Skill, Will, and No Backfire.

Skill - is it feasible that we'd be able to construct a working smart highway and feasible that drivers would understand how to use it? They'd understand where to get their updates and understand the alternate routes being suggested?

Will - would drivers be willing to listen for these updates? Would they be willing to take alternate routes or would they stubbornly think "I'm not takin' orders from no computer!"

Backfire - could there be some unanticipated thing that goes wrong with this plan and creates more traffic? When everyone gets the same warning at the same time () will it create new accidents or new traffic as they all try to go for the same alternate route at the same time?

Goal

It's hard to anticipate the answer because it will probably be ruling out a possible objection, or establishing some minimum bar of feasibility.

I would mainly be thinking,

Eva’s argument depends on the assumption that

on “smart highways” there would
Too Strong: no breakdowns
The author is fine believing that cars will still break down. She is just thinking that when they break down, the smart highway will warn cars to take an alternate route, and so the broken-down-car in the middle of the highway won't cause as big a traffic build up as before.
22% picked this
traffic lights, if coordinated by
Too Strong: assure a free flow
The author is expecting improvements, not perfection. She doesn't need to assume that coordinated traffic lights would 100% of the time assure a free flow of traffic.
10% picked this
Correct
traffic flow in and around
Why this is right
This is basically saying the author assumes that "improvement is possible". Sure, she definitely is assuming that. Whenever Necessary Assumption answers are ruling out an idea with the word not, we are attracted. We want to slow down, negate that "not", and figure out if the answer becomes an objection (if it does, it's the correct answer). Does it hurt the author's argument to say that "traffic is now so congested that significant improvement is impossible"? Yes. Technically the conclusion only promised improved traffic flow, not significantly improved traffic flow, so on that level it doesn't weaken. But when you think about the fact that the author is also promising a change to drivers' tempers, that wouldn't happen with only insignificant improvement in traffic flow. And given that her ultimate conclusion is that a "smart highway" system should be installed, it weakens her argument if we're saying that "you think we should spend a lot of time and money developing a system that only offers insignificant improvement?" (whoever at LSAC wrote this question probably lived in Los Angeles at some point. The traffic in LA is awful because way more people live here than should. When traffic occurs in one place, we all try to bail to the same alternate routes, and those also get choked up. There are just certain times of day and parts of the town where there is no way to avoid traffic.)
Skill tested: Necessary Assumption · how this choice captures the argument's function is the move to repeat next time.
64% picked this
the type of equipment used
Out of Scope: varying equipment
It's not clear why the author would need to assume that different cities use different equipment. Would it hurt her argument if different cities used the same type of equipment? No, if anything that sounds efficient and standardized.
3% picked this
older vehicles could not be
Weakens
This also has a ruling-out "not", but when we negate this answer, it actually helps the argument: older vehicles could also be fitted with equipment to receive signals sent by a "smart highway" system. The answer as written actually weakens, because it's saying that the older cars on the road wouldn't hear these smart-highway updates and so wouldn't know what to avoid or how to avoid it.
1% 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