QUESTION TEXT: Biologist: Humans have five fingers because we…
QUESTION TYPE: Strengthen
CONCLUSION: If humans had descended from a six phalanged fish then we would be just as happy with six fingers.
REASONING: We only have five fingers because we descended from fish with five phalanges. Having five fingers is no more or less useful than any other arrangement.
ANALYSIS: It’s clear from the biologist’s evidence that six fingers actually would be just as useful. The right answer shows that we are always equally content with things of equal usefulness.
___________
- This doesn’t matter, as long as we would have the same average level of contentment if we had six fingers instead.
- This strongly weakens the argument. We would not be equally content with six fingers even though they would be equally useful.
- CORRECT. Since six fingers are equally useful we would be equally content with them.
- This doesn’t tell us that we would be just as content with six fingers. Our illusions might cause us to believe they were more or less useful.
- The biologist is speaking hypothetically. It doesn’t matter if such a fish actually existed. The biologist is asking us to consider what would happen if it had existed and if we had descended from it.

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Isn’t B the contrapositive of C? This question stumped me. Thanks!