Self-study
Physics professor: Some scientists claim that superheated plasma in which electrical resistance fails is a factor in causing so-called "ball lightning." If this were so, then such lightning would emit intense light and, since plasma has gaslike properties, would rise in the air. ████████ ███ █████████ ██ ████ █████████ ████ █ ████████ ████ ██ ███ █████████ ███ ███████ ████████████ ██████ ██████████ █████ ███████████ ██████ ████ ██████ ██████████ ██████████ ██ █████ █ ██████ ██ ███████ ████ ██████████
Summary
The professor concludes that superheated plasma is never a factor in causing ball lightning. She supports this by saying that if it were a causal factor, then ball lightning would be intense and would rise into the air, but the ball lightning that she observed was not intense and did not rise into the air.
Missing Connection
The professor concludes that superheated plasma is never a factor in causing ball lightning, based only on the instances of ball lightning that she observed. But what if other instances of ball lightning are intense and do rise into the air? What if different instances of ball lightning are caused by different factors?
In order to conclude that superheated plasma never causes ball lightning simply because it didn’t cause the professor’s observed ball lightning, she must assume that all instances of ball lightning have the same cause.
23.
The physics professor's conclusion follows █████████ ██ █████ ███ ██ ███ █████████ ██ ████████
a
Superheated plasma in █████ ██████████ ██████████ █████ ████ ███ █████ █████ ██ █████████ █████ ████ ████ ██████████
The professor’s argument is only about ball lightning; it doesn’t matter what does or does not cause other types of lightning. (A) fails to prove that superheated plasma never causes any instances of ball lightning.
b
The phenomena observed ██ ███ ███████ █████████ ████ ████ ████████ ██ ██ █████ ███ █████ ███████
The number of people who observed these instances of ball lightning tells us nothing about whether superheated plasma is a causal factor in other instances of ball lightning. (B) fails to establish that all instances of ball lightning have the same cause.
c
Ball lightning can █████ ██ ███ ██████ ██ ███████ █████████ ████████
The fact that ball lightning can have many causal factors tells us nothing about whether or not superheated plasma can be one of those factors. (C) fails to establish that all instances of ball lightning have the same cause.
d
Superheating of gaslike ██████████ ██████ ██████ █████ ██ ██ ████████
We already know that the professor’s observed ball lightning did not emit intense light. (D) fails to prove that superheated plasma never causes ball lightning, nor does it establish that all instances of ball lightning have the same cause.
e
All types of ████ █████████ ████ ███ ████ ██████
The professor’s ball lightning was not intense and did not rise into the air, so superheated plasma didn’t cause it. If all types of ball lightning have the same cause, this guarantees the conclusion that superheated plasma never causes ball lightning.