Self-study
Support In our solar system only one of the nine planets—Earth—qualifies as fit to sustain life. ████████████ █████ ████ ██████ ███ ███████████ ███ █████████████ █████ ██████ ██ █████████ ███████ ██ ███ █████████ ██ ████ ████████ ████ ███ ██████ ██ ███████ ███ ██ ███████ ████ ████ ██ ████ ██ █████████ ██████
Summarize Argument
The author concludes that there must be a very large number of planets in the universe that are fit to sustain life. He bases this conclusion on the fact that in our solar system, one out of nine planets can sustain life. The author then argues that if you apply this ratio to all planets in the universe, you would end up with a large number that could sustain life.
Identify and Describe Flaw
The author never provides any basis for his application of the one-in-nine ratio from our solar system to the rest of the universe. Without giving us any reason to believe that other solar systems are similar in planetary makeup to ours, the author’s conclusion is unsupported.
25.
The argument is questionable because ██ ████████ █████ ███ ██ ███ █████████ ███████ █████████ ██████████████
a
If a planet ██ ██████████ ████ ████ ████ █████ ██ ███
The author never discusses whether or not life will arise on a planet; instead, he discusses whether or not planets are suitable for life. A planet that is suitable for life and one that has life arise on it are two different things.
b
Our solar system ██ ███████ ██ ████ █████ █████████ ███████ ██ ███ █████████
The author never explains why he thinks that the one-in-nine ratio from our solar system is applicable to any other solar system. Without giving us reason to believe this, his argument is unsupported.
c
The conditions necessary ███ ████ ██ █████ ███ ████ ███████████
Life beginning on a planet is different from that planet being suitable for life. Our author only discusses the latter in this argument, which is why this answer choice is not applicable.
d
Life similar to ███████ █████ ██████ █████ ██████████ ████ █████████ ████ █████ ██ ██████
The author never discusses life arising on other planets, and he also never compares any other life forms to Earth’s. Instead, he assumes that all other solar systems have a ratio of life-sustaining to non-life-sustaining planets similar to our solar system.
e
Most other planetary ███████ ██ ███ ████████ ████ ████ ████████
The number of planets in other solar systems is irrelevant to this argument; instead, the author is concerned with the ratio. If one in nine, or 11.1%, of planets can sustain life, the ratio applies whether a solar system has nine planets or nine thousand.