#24 - Paleomycologists, scientists who study ancient forms

[Adam Tyson]

Hey there Yusra, let me try to help.

First, in answer D, you have incorrectly diagrammed the first relationship. The sufficient condition is being with the company for more than a year. Try restating the argument in "if...then" terms - the author is saying IF you have been with the company for more than a year, THEN you can participate in the plan. The author then says that Gavin has met the sufficient condition - he has been there more than enough time - but instead of concluding that the necessary condition occurs - he CAN participate - the conclusion is that he WILL participate. We can prove he is eligible, but we cannot prove that he takes the opportunity that is available to him. Not a Mistaken Reversal, but a conclusion that brings in new information in a way that is not supported by the facts. A flaw, but the wrong flaw.

The stimulus sets up something a lot like a Mistaken Reversal, but you're right that it isn't exactly that. We don't know that Professor M is acquainted with ALL paleomycologists' work, but only that she is familiar with the work of ONE of those people. Technically, that isn't the necessary condition, but just a part of the necessary condition. But then, based on knowing that she has met at least a portion of the necessary condition (not something new - something already included in that condition), we conclude that she must meet the sufficient condition. So it is a lot like a Mistaken Reversal, but slightly modified.

The same thing happens in answer A. We don't know if ALL connecting flights were delayed, but only that Frieda's was, and from that partial info we conclude that the sufficient condition must have also occurred. It's a lot like a Mistaken Reversal, but modified in the same way (we only know that a portion of the necessary condition occurred).

Check out that relationship in answer D again, and compare it to your diagram. Keep up the good work!

[dlddls37]

Isn't Mistaken Negation practically the same as Mistaken Reversal in that the logical flaw behind them are identical?
I see how AC (A) perfectly matches the flaw in the stimulus but (B), formulated as Mistaken Negation, seems to have a same logical flaw.

[Rachael Wilkenfeld]

Hi dlddls37,

Great question. A mistaken reversal and a mistaken negation are logically equivalent but different ways of presenting an error. It's the difference between repeating a statement and between giving a statement and its contrapositive. Logically it's the same, but it's still different. It is unusual for a parallel flaw question to show both the mistaken negation and the mistaken reversal as options where only one is correct, but it does happen. Think about what each of the mistakes is doing. A mistaken reversal is saying that because the necessary occurs, the sufficient occurs, The mistaken negation is saying because the sufficient does not occur, the necessary did not occur. Those are different ideas in the flaw.

Hope that helps.

[teddykim100]

Hi,
this is more of an abstract/theory question, but if we take answer choice B, which says

if miss shift work harder than usual

and then take the contrapositive,

if -(work harder than usual) -(miss shift)

the conclusion of B is a reversal of this contrapositive

I know I'm going in circles here, but isn't the same flaw the original argument commits? A reversal. And if the contrapositive of a statement is the logical equivalent of a conditional statement, isn't that the same flaw?

[Robert Carroll]

Hi,
this is more of an abstract/theory question, but if we take answer choice B, which says

if miss shift work harder than usual

and then take the contrapositive,

if -(work harder than usual) -(miss shift)

the conclusion of B is a reversal of this contrapositive

I know I'm going in circles here, but isn't the same flaw the original argument commits? A reversal. And if the contrapositive of a statement is the logical equivalent of a conditional statement, isn't that the same flaw?

teddy,

It's the same flaw but not parallel. I wrote a post on this difference: viewtopic.php?p=87775#p87775

Hope that helps!

Robert Carroll