Q16 - In yesterday's council election

[ptraye]

What is the name of the flaw in the stimulus?

[timmydoeslsat]

V most CC
V most CFAP
____________

Conclusion?

A valid conclusion would be that there is at least 1 voter that is both CC and CFAP.

V some (CC and CFAP)

This invalid conclusion in this argument is:

V most (CC and CFAP)

This is a some-most switch in the conclusion. The error in this argument is that we do not know for certain that most can be used. We do know that some is used. Conclusions are things that can be proven from the premises given. Some can be proven in this context while most cannot.

Answer choice B is the closest one that mirrors this flaw:

C most P
C most B
__________
Conclusion?

The true conclusion is that there is a C that contains P and B. In the context of this argument, it is the case that there is at least one child that likes both pies and blueberries. The one issue I do not like about this conclusion is that it combines them in an extra flawed way. This conclusion not only has the some/most switch issue, it also confuses the issue that a person can like blueberries but not like blueberries pies.

This conclusion would have been invalid in a parallel way with just the idea that: C most (P and B). However, it goes even further from logical validity by it talking about a majority of C liking blueberry pies.

A) I want the most/some switch in the conclusion. This is an error of talking about can in evidence and then claiming that something will happen in the conclusion.
C) Wrong logical error. This is reversed logic.
D) Issue of bringing in new terms. We go from talking about a majority of customers who regularly eat at the restaurant...and then talk about what is the most frequently ordered dish. Cannot make an inference from this.
E) Same issue as D. Brings in new terms. We go from discussing most people living in the house...and then talk about most people in the house. Cannot make an inference from this.

[ptraye]

thanks.

[sumukh09]

what about the conditional statement in B) "if both sara and robert are right," shouldn't there be a conditional in the stimulus as well instead of the claim in the conclusion?

[WaltGrace1983]

what about the conditional statement in B) "if both sara and robert are right," shouldn't there be a conditional in the stimulus as well instead of the claim in the conclusion?

I was also wondering about this too! (B) is clearly the best answer but is it objectively correct if we are looking for a 100% match? I don't think so. Hmmmmm.

[WaltGrace1983]

I am going to run through the logical structure of this stuff to practice.

Most voters → Support conservative candidates
+
Most voters → Support antipollution candidates
⊢
Most voters → Support conservative + antipollution candidates

As Timmy noted, we can absolutely conclude that there are some voters that support candidates who are both conservative and antipollution. However, we absolutely cannot conclude that most voters support candidates who are both conservative and antipollution. In other words, the argument is assuming that there is a sufficient amount of overlap to conclude "most" when there may not be.

(A)

Bill: (Tilled when too wet) → (Soil can be damaged)
Sue: (Planted when too wet) → (Seeds can rot)
⊢ (Till and Plant when too wet) → (Damage both soil and seeds)

This, to me, seems perfectly valid. However, in order to eliminate (A) quickly, we can probably just understand that the conclusion has nothing to do with concluding something about a "majority" from evidence about two "majorities." I eliminated this quickly through such reasoning.

(B)

Most children → Like pies
+
Most children → Like blueberries
⊢
Most children → Like blueberry pies


This matches the flawed reasoning. We can absolutely conclude that some children like pies with blueberries but we have no idea if there is a sufficient overlap to conclude that most children like blueberry pies. Maybe there are 100 kids and 51 like blueberries, another 51 likes pies, and so only 1 kid likes blueberry pies.

(C)

Susan goes → Mark goes → ~Rain
~Rain
⊢ Susan goes & Mark goes


We only know what happens if it DOES rain, not what happens when it DOESN'T. This argument is confusing the sufficient with the necessary.

(D) This cannot be right because it doesn't separate the two things that are "most." If it would have said "most" people order X and "most" people order Y, then perhaps it would have been a better match (with a different conclusion). However, absolutely nothing matches here.

(E)

Most inhabitants → Cook well
Most inhabitants → enjoy eating well-cooked meals
⊢
Most meals → Cooked well


This was very close! However, the problem is that the conclusion doesn't match. If the conclusion would have said, "Therefore, most inhabitants cook well and enjoy eating well-cooked meals." However, we know nothing about the actual meals themselves.