Really interesting question,
WaltGrace1983!
What if we took a real life example that could use this language?
Astronauts tend to be better at science than the non-astronaut population. Jody was better at science than anyone else in her university. Therefore, she is probably an astronaut.
This is nonsensical! But why is it nonsensical? Because there are only a tiny number of astronauts in the world, and tons of non-astronauts, and that affects the likelihood of Jody falling into the 'astronauts good at science' category as opposed to the 'non-astronauts good at science' category.
Let's take another classic:
U.S. Presidents have tended to be white males. Brad is a white male. Therefore, Brad is probably President of the United States.
Now, notice how the exact same flaw occurs with this rewording:
Most U.S. Presidents have been white males. Brad is a white males. Therefore, Brad is probably President of the United States.
All these scenarios exhibit the same essential flaw. The original stimulus (and the astronauts) give us a comparison between the two groups, but don't give us any info on the relative SIZE of the two groups. The U.S Presidents example gives us a 'most' statement about one group, but again, no info on the relative sizes of the two groups (Presidents and non-presidents).
You're absolutely right to be wary of treating treating the "when" statement as a normal conditional statement - remember that true conditional statements are
guarantees. Statements that look like conditionals, but end with a 'probably' claim are much more like 'most' statements! Consider the relationship between these two statements:
Most of the apples on the table are red.
If you are an apple on the table, you are probably red.
These two statements express the exact same information.
Ultimately, the flaw in the stimulus is functionally identical to the one exhibited in the astronauts example. To make a claim about how likely it is that someone with awesome grades went to a single-sex school, we'd need to know what percentage of 'awesome grade people' went to single-sex schools! To make a claim about how likely it is that someone who is awesome at science is an astronaut, we'd need to know something about the proportion of 'awesome science people' that are astronauts!
Now, the interesting thing about this question is that you don't actually have to understand any of that in order to get through this particular question. All you have to do is match up the structures one by one. But I think you knew that.
For the sake of future readers, I'll go through that process now.
First, the stimulus starts with a "When X, then usually Y" statement. All five of our answer choices start with a similar statement, so that doesn't help right off the bat. However, the meat of the argument comes next: the author brings up a specific person, and tries to apply the "When X, then usually Y" idea to that person.
Glancing through the answer choices, only
(A),
(B), and
(D) have a specific person raised. Eliminate
(C) and
(E).
Now, after saying "When X, then usually Y", the stimulus says that Alice did
Y, then makes a conclusion that she probably did
X. Pay attention to which elements are used and in what order!
(A) says Celia did X, then makes a conclusion that she will probably Y. That's the reverse order of what we want!
(D) says that Sally DIDN'T do X, then makes a conclusion that she probably WON'T do Y. This is completely different from what we want!
Only
(B) matches: Janice has Y, so the author concludes she probably did X. Perfectly aligned with the stimulus.
[Bonus points: looking at the first statement, the original stimulus goes a bit farther than to say "When X, usually Y". It actually says "When X, Y is more likely than it is otherwise". In other words, the stimulus makes a comparison between one group and everyone else.
Looking only at the first sentence of each answer choice, only (B) gives a comparison (between swimming babies and average non-swimming babies). Every other statement misses the comparison. (A) simply says the students usually get good grades - it does NOT say they get BETTER grades than the other students. (C) doesn't say these kids appreciate the variety MORE than other kids. (D) doesn't say these kids are MORE LIKELY than other kids to pass the piano exams. (E) doesn't say these kids to BETTER than other kids in school.Please let me know if this helps clear things up a bit!
