Principle: It is healthy for children to engage in an activity that promotes their intellectual development only if ...

shunhe on September 14, 2020

Hi @CMarr,

Thanks for the question! Let’s take a look at the stimulus. So first we’re given a principle. It’s healthy for kids to engage in an activity that helps their intellectual development only if it doesn’t take away from their social development. Well, we can diagram this. It’s an “only if,” which introduces the necessary, and so this is diagrammed

Healthy to participate in activity that promotes intellectual development —> ~Detract from social development

Now we have this application. We’re told that there’s this activity Megan does that promotes her intellectual development but takes away from the time she spends interacting with other people (and is supposed to mean that it would take away from her social development). And the application then concludes that it’s not healthy for her to read as much as she does. So what did this argument do? Well it used this principle:

Detract from social development —> ~Healthy to participate in activity that promotes intellectual stimulation

So (E) says that the argument takes a necessary condition for an activity’s being healthy as a sufficient condition for its being so. This describes a mistaken reversal. But did it do this? No, it didn’t, it took the contrapositive, which is a totally legit thing to do! And so (E) isn’t the correct answer here.

Now let’s take a look at (D), which tells us that the argument takes for granted that any decrease in the amount of time a child spends interacting with others detracts from that child’s social development. This is true! The argument basically equates taking time away from interacting with other people and detracting from social development. But this might not be the case. Maybe she has too much social time with people now, or maybe the difference between 5 hours of socializing and 4.5 hours of socializing doesn’t make a difference. Either way, this is an assumption the argument makes without justification that isn’t immediately obvious, and so (D) is the correct answer here.

Hope this helps! Feel free to ask any other questions that you might have.