QUESTION TYPE: Flawed Reasoning
CONCLUSION: The anthropologists are wrong to say that prehistoric human survival required the ability to cope with diverse environments.
REASONING: One prehistoric species related to humans had the ability to thrive in different environments, but became extinct.
ANALYSIS: This argument mixes up sufficient and necessary conditions. The anthropologists argued that coping with diverse environments was necessary: “Survive ➞ ability to cope”. Contrapositive: ability to cope ➞ survive
The author gets things backwards with their evidence. The author mistakenly assumed the statement was “ability to cope ➞ survive”, and that Australopithecus afarensis was a counterexample disproving the statement.
But in the anthropologists’ version, the ability to cope was necessary, but not sufficient. So a species failing to survive doesn’t disprove the claim. (You’d instead need to show a human species surviving without the ability to thrive in a diverse array of environments)
- CORRECT. See the analysis above. The ability to cope was a necessary condition for survival. The author got confused and assumed it was a sufficient condition.
- This didn’t happen, and this assumption doesn’t make sense: why would someone assume this?
Example of flaw: Humans have ears, and these helped us survive. That means at least some of our extinct relatives had ears.
- Like B, this didn’t happen. Instead, the author was assuming that not all species survived.
Example of flaw: Humans had bones, and survived an ice age. So all of humanity’s relatives with bones must also have survived ice ages.
- In a conditional statement, fulfilling or not fulfilling the condition is what’s important. If I say @To buy a house, you need [email protected], I don’t care why you do or don’t have money. In terms of fulfilling the necessary condition, only having the money matters.
@[email protected] was the (implied) sufficient condition in the author’s argument. So, the important point was that Australopithecus afarensis didn’t survive. Why it didn’t is unimportant.
The author’s actual flaw was mistaking a necessary condition for a sufficient one. @[email protected] was actually the anthropologists’ necessary condition, not sufficient.
- This is a different flaw. The example below shows a flawed argument using the method described in this answer.
Example of flaw: A police officer was shot by a bank robber yesterday. The bank robber had surprised the police officer using a bank security guard’s uniform.
Therefore, in all cases of shootings of police by bank robbers, the bank robber must have a bank security guard’s uniform.
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