LR Question 10 Explanation
QUESTION TEXT: To accommodate the personal automobile, houses are…
QUESTION TYPE: Flawed Reasoning
CONCLUSION: The geography of modern cities would have to have been very different if people had not used personal automobiles.
REASONING: The automobile has caused houses to be scattered far apart and far from work. Giant shopping mall parking lots have left little place for woodland.
ANALYSIS: This argument is almost good, but the conclusion is too definite. If it had said that cities “would probably have been different” it would have been ok. Cars undeniably did change cities, and cities probably wouldn’t have changed so much without cars.
But the argument claimed that cities would definitely have been different.
It’s possible cities could have developed in the same from some other cause. Personal jetpacks?
___________
- CORRECT. Cars were a sufficient condition for current geography. But we have no indication that they were a necessary condition.
- The argument is confined to geography. It doesn’t mention other parts of life.
- The argument doesn’t claim that cars are the only influence. It just makes the point that they were a major influence and cities would look different without them.
- Actually the argument says that malls do need large parking lots.
- The argument isn’t saying what should be done. It’s making a factual analysis. Maybe the author of the argument loves cars.
More Resources for Flaw Questions
- Flaw drills: Use these to practice making examples of abstract flaws.
- Intro Course lesson: This intro course lesson covers Flaw questions.
- Mastery Seminar lesson: This LR Mastery seminar lesson covers flaw questions.
I’m in the phase where I review all hard/confusing LR questions and try to play the devil’s most vicious advocate when eliminating answer choices. Means, most of us would eliminate (C) under time pressure simply because it’s way more vague and less clear than (A). But, for the sake of sharpening our LR skills (which might be crucial for harder questions), let’s view this choice from a structural perspective only, and assume that (C) says “geography” than “way people live”.
Now, what? Under conditional logic terms, the stimlus says:
Premise: A –> B
Conclusion: notA –> notB.
Means, the premise says A is a suffcient condition for B, and in the conclusion it is treated as necessary. THIS is the flaw, and it is clearly stated in (A).
Good, but how about (C), why is it wrong? (C) basically says that the stimulus overlooked the fact that there might be a combination of sufficient conditions which led to B, or, in conditional logic terms:
Stimulus assumes A –> B, while it could be the case that (A + C) –> B.
Now, even if the stimulus overlooked that, is it really a flaw?
Premise: (A+C) –> B
Conclusion: notA –> notB.
Now, compare the two versions. The conclusion is wrong for the same reason, whether we include or leave out C. Therefore, the problem is NOT the fact that the sufficient assumption might be incomplete, but the fact that it is treated as necessary!!!
It’s like saying: “Einstein discovered relativity theory. Therefore, if Einstein had not lived, relativity theory would never have been discovered.” And somebody jumps in and says: “But, you overlooked the fact that there were a dozen people who assisted Einstein with his experiments, therefore they had a mentionable contribution to it as well.” Yes, I overlooked it, but why on earth would it identify the flaw in my argument?!