PrepTest 130

Correct. Argument or Facts:
Argument

Valid or Flawed:
Flawed

Question Type:
Errors in Reasoning

Stimulus Summary:
Correlation: Damage to chromosome 6 and schizophrenia
Counterexamples: People with damage but no schizophrenia; People with schizophrenia but no damage to chromosome 6
Conclusion: There is no causal relationship between damage to chromosome 6 and schizophrenia

Answer Anticipation:
An interesting twist on a common flaw! Normally, an argument on the LSAT jumps from correlation to causation. However, in this case, the argument brings up a correlation only to highlight some counterexamples that seem to show there isn't causation! The argument then reaches a conclusion that the two phenomena have "no causal connection."

However, that's too extreme of a conclusion. While highlighting counterexamples can show that the causal relationship isn't absolute—that the cause always leads to the given effect, and only that cause leads to the given effect—but it's not enough to show that there's no causal relationship between the two. Maybe only certain types of damage to chromosome 6 lead to schizophrenia, or only damage when coupled with another factor leads to the disease, while other causes can also lead to it.

Answer Explanation:
This answer highlights one possibility the argument ignores—that some types of damage to chromosome 6 do cause schizophrenia while others don't. This would explain those people with damage to the chromosome who don't have schizophrenia while still leaving open the possibility of a causal connection.

Key Takeaway:
There is a lot of subtlety to correlation/causation arguments that the LSAT can play around with to create questions that deal with these topics in a non-standard manner. Whenever you come across a question that isn't a straightforward jump from correlation to causation, spend some time reviewing it to see what you can learn about those concepts from it. The more you know about causal logic, the better you'll do on the LSAT!

Incorrect. The argument assumes that if not everyone with damage to chromosome 6 has schizophrenia, then that chromosome isn't related to schizophrenia. The argument rules out damage to one chromosome as a causal factor, but it doesn't eliminate or assume that damage to another chromosome is the actual cause.

Incorrect. There's no indication that the studies were done on an unrepresentative sample. Without information in the stimulus establishing the sample as unrepresentative, a generic sampling flaw answer is incorrect.

Incorrect. The argument concludes that two things aren't causally related, so it's not mistaking cause and effect. (Note that this is the reversed causality answer.)

Incorrect. While this is the flaw that you may have expected after the first sentence, the argument zigs instead of zags and rules out causality despite the correlation.