Self-study
Support If a civilization as technologically advanced as human civilization existed on another planet and that planet were within 50 light years of Earth, that civilization would have found evidence of intelligent life on Earth and could have easily contacted us. ██████████ ███ ████ ████ ███ ███ ███████████ ██ ███████ █ ████████████ ██ ███████████████ ████████ ██ ███ ███ ██████ ██ █████ █████ ██ ██████
Summary
If a certain kind of alien civilization existed, they would know about humans and have the ability to contact us. We haven’t been contacted, so the civilization doesn’t exist.
Notable Assumptions
The author gives a conditional rule, and then tries to negate the necessary condition (knowledge of us and can contact us) so that she can negate sufficient (existence). This would be acceptable if that was what the author did, but it wasn’t:
The author is, through implication, invoking the absence of contact in an attempt to negate the ability to contact, but those two things are not the same. Phrased differently: Just because the aliens can contact us doesn’t mean they will. We need to know that if they can, they will contact us.
4.
Which one of the following ██ ██ ██████████ ████████ ██ ███ █████████
a
Scientists who are █████████ ███ ████████ ██ ████████████████ ████ █████ █████████ █████ █████ ██████ ██ ████████ ██ ███████████████ ████████ ████ ██████
We don’t need scientists to be especially focused on the extraterrestrials described in the stimulus. It has no effect on the argument if they do or not.
b
There is no ██████ ██ █████ ███ ███████████ ████ █████ ███ ███████████████ ████████ █████████████ ██ ███████ ████ ████ ██ █████ █████ ████ ██████
We are not discussing civilizations more than 50 light years away from us. We are discussing civilizations that are 50 light years away or closer.
c
If scientists received █ ███████ ████ █ ███████████████ ████████ ████████████ ██ ███████ ███████ ████ █████ ██ ████ ██ ████████ ██ ██████
It isn’t necessary that scientists fully understand the alien’s message. It is necessary that, if the aliens were to contact us, we would know they had done so. But (C) is not required for that to happen.
d
A technologically advanced ████████████ ██ ███████ ██████ █████ ████ ██ ███████████ ████ ███████████ ████ ████ ██ ████████ ██ ██████
This is our prediction, and it is necessary. If the civilization doesn’t want to communicate with us, then the author’s reasoning for ruling out their existence has crumbled. The aliens could exist without us ever hearing from them.
e
Intelligent life forms ██ █████ ███████ █████ ██ ████ ██ █████████ ███ █████ ██ ███████████ ████ ██ ██████
Too strong. It is necessary that the alien civilization recognizes life on Earth as intelligent, but they do not need to be able to recognize all signs of intelligent life.