By referring to the Universal Declaration of Human Rights as "purely programmatic" (line 49) in nature, the author mo...

Skylar on September 28, 2019

@Adri Maybe I can help. Let's take a look.

We can break the passage down as follows:
Premise: In some experiments, genetic mutations occured at random.
Premise: Missing - this is what we the answer choice we are looking for will provide.
Conclusion: All genetic mutation is random.

So, we are looking for the second premise that will connect the idea that "genetic mutations occured at random in some experiments" to the idea that "all genetic mutation is random." Answer choice (A) does this, as Mehran explains in the video.

(C) is incorrect because it does not provide the missing link. Instead, it creates a new S->N statement based on the Sufficent condition "IF all genetic mutations in bacteria are random." Note that answer choice (C) only sets up a hypothetical "IF" statement. It does not state anything definitively about genetic mutations that would be helpful in connecting our premise to our conclusion. Therefore, it is irrelevant and incorrect.

Does this make sense? Please let us know if you have any other questions!

JYL on February 3, 2022

Hi, I am also trying to figure out the explanation for 15..

The passage breakdown confuses me because it seems to completely ignore the detail that the experiment was done on bacteria..

My breakdown of the passage looked like this:

Premise: Genetic mutations in bacteria occurred at random
Premise: _____

Conclusion: All genetic mutation is random

What filled the Missing Premise for me would have been C... but the explanation came up with an entirely different passage breakdown.. which I clearly didn't get to myself.


Ultimately, my question is: how can someone discern which additional information is relevant? Why were experiments on bacteria generalized to "some genetic mutations" as a whole?

Ravi on February 4, 2022

The issue with C is that the stimulus never tells us that all genetic mutations in bacteria are random. It just says that the mutations in these particular bacteria are random.

A works because we know from the stimulus that it's not the case that no mutations are random since we have a group of bacteria with random mutations. So if this statement is true, then the only possibility is for all mutations to be random, so the conclusion of the argument is guaranteed.