LR Question 24 Explanation
QUESTION TEXT: In the Riverview Building, every apartment that has a…
QUESTION TYPE: Flawed Parallel Reasoning
CONCLUSION: One Bedroom ➞ ~Fireplace
REASONING: Balcony ➞ Fireplace
Balcony ➞ ~One Bedroom
ANALYSIS: This argument mixed up necessary and sufficient conditions. Having a balcony is sufficient to have a fireplace, but it isn’t necessary. There can be apartments with fireplaces and no balconies.
It’s possible that every apartment has a fireplace.
Structurally, the argument takes both necessary conditions and combines them, incorrectly.
Note that the translation for ‘No politician is honest’ is P ➞ ~H. You negate the necessary condition.
___________
- Fish ➞ Fur – Conclusion
Cat ➞ Fur
Cat ➞ ~Fish This is a strange argument, but it doesn’t mix up sufficient and necessary. Note that the necessary conditions weren’t combined in the same way. Neither is negated in this conclusion. - Rule this out right away; it uses a ‘some’.
- CORRECT. Dog ➞ ~Fur – Conclusion
Cat ➞ Fur
Cat ➞ ~Dog This mistakenly assumes that Cat is necessary for Fur, because Cat is sufficient. Note also that the two necessary conditions have been used to make a statement. - Cat ➞ Fish – Conclusion
Cat ➞ ~Dog
Dog ➞ ~Fish Nonsense, but no sufficient-necessary error. - Fish ➞ ~Dog – Conclusion
Dog ➞ Mammal
Fish ➞ ~Mammal This is a good argument!
More Resources for Flawed Parallel Reasoning Questions
- Conditional Reasoning Article: Learn about conditional statements.
- LR Diagrams Guide: Learn how to draw LR diagrams.
- Flaw drills: Practice identifying flaws.
- Intro Course lesson: This intro course lesson covers Flawed Parallel Reasoning questions.
- Mastery Seminar lesson: This LR Mastery seminar lesson covers flawed parallel reasoning questions.
Hi Graeme,
When you are doing this question or one like it, do you write out all the diagrams? I assume not, you probably visualize it. But, would analyzing the structures of both to narrow down the options then diagramming if necessary be the optimal strategy?
I think on this one I drew the setup and probably none of the answers but would have been prepared to draw 1-2 if needed.
Hey Graeme,
Your explanations are pretty awesome. They are extremely helpful due to their simplicity of analysis. However, i think you should review this question. The conclusion as stated is wrong and so is the note i believe. The conclusion says: 1B—-> No fireplace. I am guessing that your note should say, No politician is honest= P——> Not Honest.
If otherwise i would like to know please.
It’s great to hear that you’ve gotten so much from Graeme’s explanations! And thanks for catching those small typos in the explanation. The page has been updated.