Q25 - If squirrels eat from a bird feeder

[e. chung]

Can someone help me with the formal logic on this one?

The stimulus:


squirrels eat from feeder -> ~attract many birds
squirrels eat from feeder -> ~protective cover
______
~protective cover -> ~attract many birds


The correct answer is B.


Low -> wear out prematurely
Low -> ~check pressure regularly
_____
~check pressure regularly -> wear out prematurely

Doesn't 'wear out prematurely' have to be negated, in order for B to match the stimulus? Or is 'wear out prematurely' already a sort of negation, like 'not lasting long enough?'

Help is very much appreciated!

[ohthatpatrick]

Great work!

We don't have to be so picky that we insist on "negative ideas" for the right side ideas of the conditionals in the correct answer.

The flaw was merely one of
A --> B
A --> C
Thus, C --> B

It doesn't matter whether B is "not attracting birds" or whether B is "wears out prematurely". It only matters that in the conclusion, the author foolishly tries to chain together the two necessary ideas from the two conditionals.

As we go to these answers, one of the time-saving things we should be asking ourselves is, "Are there three conditional statements?" The original had two conditional premises and one conditional conclusion. If I don't immediately see three conditionals, I'm not reading the whole thing.

Another time-saving thing I would keep in mind is, "Do I have two premise conditionals that have the SAME trigger idea?"

(A) 2nd idea isn't a conditional that begins with "if tire pressure too low" .. also 2nd idea isn't conditional ('likely cause').

(B) Correct

(C) 2nd sentence doesn't have a rule that begins with "if neglect". Eliminate.

(D) 2nd sentence doesn't have a rule that begins with "if tire pressure too low"

(E) 2nd sentence doesn't have a rule that begins with "if tire pressure is too low".

Hopefully you see why being super clear about the ingredients you need can speed things up.

For (A), (C), (D), and (E), I never even got to their conclusion. I simply looked at the trigger in the first sentence and then checked to see whether the 2nd sentence had the same trigger. If it didn't, then there was no need to read. There's no way we'd get that
A -> B
A -> C
structure of the original premises.

Hope this helps.

[contropositive]

Great work!

We don't have to be so picky that we insist on "negative ideas" for the right side ideas of the conditionals in the correct answer.

The flaw was merely one of
A --> B
A --> C
Thus, C --> B

It doesn't matter whether B is "not attracting birds" or whether B is "wears out prematurely". It only matters that in the conclusion, the author foolishly tries to chain together the two necessary ideas from the two conditionals.

As we go to these answers, one of the time-saving things we should be asking ourselves is, "Are there three conditional statements?" The original had two conditional premises and one conditional conclusion. If I don't immediately see three conditionals, I'm not reading the whole thing.

Another time-saving thing I would keep in mind is, "Do I have two premise conditionals that have the SAME trigger idea?"


(C) 2nd sentence doesn't have a rule that begins with "if neglect". Eliminate.

Thank you for your explanations. They have helped me so much. I am confused about something though.

On Preptest 65 Section 1 Question 11 with the same type of question, samantha.rose.shulman (the 1st poster) explained that one time-saving strategy on these types of questions is to eliminate answer choices based on the degree of the conclusion. For example, in that question the conclusion was definitive "must".
In this question the degree of the conclusion is "will not." But if we apply Samantha's strategy then B would be eliminated because it says "will" and the conclusion in the original argument is "will not".

Her strategy works for regular parallel questions but I don't know if that is safe to apply for flaw parallel? I am thinking perhaps there is a difference because this argument had conditionals and Prep65 argument does not have conditional statements?

Also, applying your strategy, couldn't C also be wrong because it does not have a 3rd conditional statement like our original?

[ohthatpatrick]

Yes, C could be wrong for not having three conditionals. I basically was saying there were two quick checks we could use on this problem:
- are there three conditionals?
- do the first two conditionals share the same trigger?

I was using the latter approach, just cuz.

In terms of the test 65 thing, what you're looking for is the same degree of certainty.

Is the author concluding with certainty?
must, only, will, will not, cannot, all

Is the author concluding with likelihood?
most, usually, likely, probably, tends to, generally

Is the author concluding that something is possible at least once?
some, could, may, might, not all, not always, need not

So you don't want to be troubled by "will" vs. "will not". Those are both CERTAIN ideas.

--- However, you still alluded to an important distinction between normal Match the Reasoning and Match the FLAWED Reasoning.

For Match the Reasoning, the correct answer usually (but not always) follows the same recipe of ingredients pretty tightly.

For Match the Flaw, the correct answer need only exhibit the same flaw, so you will sometimes see some pretty big structural differences (f.e. the correct answer might use an Either X or Y claim, even though the original didn't)

As long as the Flaw is the same, it's a good answer. So be ready to be a little more flexible there with all the nuts and bolts.