Self-study
It all concerns the basic form of:
A->B (if you have a rocket, you can kill a cockroach)
Immediately, based on this form, I can think of potential OPs.
It is a mistake to assume that there are no other ways to kill a cockroach. So an argument like the one below would be an error because even though A->B, it could be that C->B as well, or Z->B.
"if you have a rocket, you can kill a cockroach.
Therefore, since you want to kill a cockroach, you must use a rocket"
[A->B, therefore B->A [mistaken reversal)]. This overlooks the possibility that you can use other sufficient means to kill a rocket, and that a rocket is not necessarily necessary to kill a cockroach. It could be, but doesn't have to.
Then there another form of OP derived from the same A->B idea
And that is
A->B ; not A-> not B [mistaken negation]
"if you have a rocket, you can kill a cockroach
Since you don't have a rocket, therefore you can't kill a cockroach."
This overlooks the possibility that without a rocket, you can still do other things. Like kill terrorists. But that is out of the scope relative to the conclusion. But moreover, it is not necessarily necessary that you need a rocket to kill a cockroach, for "A->B; not A->not B" = "A->B; B->A".
In other words, it seems like the overlooked possibilities derived from the A->B form are the same.
(And that is assuming that there are no other sufficient conditions. Conclusions that follow a premise of A->B and concludes in the form of not A -> not B and B->A are making the same flaw and that is missing OPs.
What are your thoughts on this?
What are some implications that I have missed?
the author assumes that Selena is sufficient evidence to indicate possibility, (that she is not an outlier of sort). Just by showing Selena's case, it is enough to prove the possibility.
But the author never makes this assumption explicit. And that's what we should do.
So if she has powers, then it is good enough evidence to make the conclusion that it is possible.
If she doesn't have powers, then is it good enough evidence to make the conclusion that power is possible still?
Well, what if she is an outlier? That even though she doesn't have power, Professor X nonetheless has power and that proves the possibility of having powers? This is the gap. The author doesn't think this can happen.
That if she doesn't have powers, then it's impossible to have powers.
Or
if it is possible to have powers, then Selena has them!