Q23 - A species in which mutations

[ohthatpatrick]

What does the Question Stem tell us?
Match the Flaw

Break down the Stimulus:
Conclusion: if you mutate frequently, you can survive big changes to enviro.
Evidence: If you mutate frequently, you'll have new adaptations every generation … and … if you survive big changes to enviro, then you have new adaptations every generation.

Any prephrase?
Close, but not quite, Author. She's trying to chain together conditionals to derive her conclusion, but she's using one of them backwards. She WANTS "frequent mutations --> adaptations every generation --> survive big changes". But that last link is incorrect. The premise she provides us with says "survive big changes --> adaptations every generation". So the recipe of what we're looking for is two conditional premises: A --> B and C ---> B, and then a conditional conclusion that tries to chain them together: A ---> C.

Answer choice analysis:
A) Quick glance: two conditional premises. But the common idea, "properly built," is showing up once on the left and once on the right, so you CAN chain these together. The conclusion is only invalid because it switched from "stone wall" to "wall".

B) Quick glance: don't seem to be two conditionals with an overlapping ingredient. The first conditional is saying "if performed for different audience every time" and the second is saying "if a play, then not performed for same audience every time". There's a difference between "being perfomed for different every time" and "not being performed for same every time". The latter allows for the same audience multiple times, the former doesn't.

C) The overlapping ingredient "tell the truth" shows up both times on the right side. And the conclusion tries to merge together the two triggers. This looks good.

D) "well drained" shows up once on the right, once on the left, so it CAN be chained together. The conclusion looks valid.

E) "well balanced" CAN be chained. The conclusion is only wrong because they switched from "healthful diet" to "whether or not one is healthy".

The correct answer is C.

Takeaway/Pattern: Match the Flaw typically offers us Classic Flaws as the problem with the original. Here, we have the Conditional Logic Flaw (nec vs. suff). An author used a conditional backwards to derive his conclusion. Since processing all five answers is a drain, try to look for a simple indicator of whether it's worth fully reading. Here, it was helpful to look for the common ingredient in the two premise conditionals and see whether it chained or whether it was two right side ideas.

#officialexplanation

[AllyMaeBell]

Please see the attached explanation and diagram. Thanks!

[bdk980]

That seemed like a super-complex answer. This might be simpler. We are looking for the flawed pattern of reasoning that most closely parallels the argument above...

A species in which mutations frequently occur (label this A) ...will develop new evolutionary adaptations in each generation (B). Since species survive dramatic environmental changes (C) only if they develop new evolutionary adaptations in each generation (B again) a species in which mutations frequently occur (A again) will survive dramatic environmental changes (C again).

The final arrangement structure for the stimulus is AB. CB. AC.
That is exactly the way answer choice (c)'s argument is structured.

**This only work well when they answer choice's reasoning is suppose to "parallel" that in the stimulus.

[ManhattanPrepLSAT1]

Nice work bdk980!

The final arrangement structure for the stimulus is AB. CB. AC.

I like that you focussed on the abstract, since when we match a flawed argument, we need to apply the abstract reasoning to a new argument. But I'd caution you against representing the argument's logic AB. CB. AC.

Instead note it using conditional statements or quantified statements when appropriate.

A --> B
C --> B
---------
A --> C

Or you could keep in the terms given.

MF --> NA
S --> NA
------------
MF --> S

This argument reverses the relationship implied in the second premise. If this were a flaw question, you could say that the argument mistakes a required condition for one that is sufficient.

[carly.applebaum]

can we eliminate A, D, and E right off the bat since none of them use the future tense "will" like the stimulus does? only B and C use "will"...just trying to eliminate the matching part quickly so that i don't spend my time diagramming all of the answer choices.

thanks!