PrepTest 128, Section 2, Question 23
Some people believe there is intelligent life somewhere(38 more words not shown)
The reasoning in which one(13 more words not shown)
- ASome people believe(36 more words not shown)
- BSome cat owners(45 more words not shown)
- CSome dog owners(36 more words not shown)
- DSome people believe(36 more words not shown)
- ESome people believe(36 more words not shown)
Reading the argument
This argument is about what people believe, not whether intelligent life actually exists elsewhere. Some people hold the first belief, and the next sentence tells us that anyone holding it cannot also believe that every other planet is lifeless.
You might wonder whether someone could imagine life on a moon or an asteroid instead of a planet. But the passage supplies the restriction on those people's beliefs as a premise. Our task is to match the reasoning that follows from it, not replace it with a different rule.
What we’re looking for
The structure is: some people hold one belief; nobody can hold that belief together with a second belief; therefore, some people do not hold the second belief. Notice the careful ending. Not believing that all other planets are lifeless isn't itself a declaration that those planets actually contain life. Keep the conclusion at the level of what these people do not believe.
Working the answers
- A
The second sentence does connect the beliefs, despite its difficult wording. If nobody who lacks belief in computer chess successes believes computers can think, then anyone who believes computers can think must also believe in those chess successes. Since some people hold the first belief, we can infer that some hold the second.
But A concludes that the chess programs actually beat human masters. That jumps from what people believe to what happens in the world. The original makes no corresponding claim that extraterrestrial life actually exists. A's failure is its factual conclusion, not a missing connection between the beliefs.
- B
The opening concerns people who believe cats are incapable of guilt. The rule then concerns believing an animal is capable of guilt: that belief requires believing it has a conception of morality. The rule doesn't tell us what people who believe cats incapable of guilt must think about morality. They could believe cats understand morality yet lack guilt. The conclusion about those owners' beliefs therefore doesn't follow by the original pattern.
- CCorrect
Believing that one's dog is emotionally attached plays the role of believing in intelligent life beyond Earth. Believing dogs are incapable of thought plays the role of believing all other planets are lifeless. The rule says nobody can hold both beliefs. Because some dog owners hold the first, some dog owners do not hold the second. That exactly matches the original's premises and conclusion, including the conclusion about lacking a belief.
- D
The connection is only probable, whereas the original's restriction is definite. There is also a direction problem: D says colonization believers probably believe overpopulation is not a problem, then concludes that some people do not believe overpopulation is not a problem. Even a definite version of the stated connection would point toward holding that belief, not lacking it.
- E
This connects belief in life on other planets with belief in life-supporting atmospheres. But it then concludes that those atmospheres actually exist. The premises would support a conclusion about what some people believe, not about the physical condition of other planets. As in A, belief has been substituted for evidence of truth.
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