Passage Summary: Researchers gave coffee to two groups—one with chocolate and one without—and found that only the group without chocolate could tell the coffees apart, leading them to blame the chocolate.

Conclusion: Eating chocolate hinders a person's ability to distinguish between different coffee flavors.

Reasoning: In a small study, the group eating chocolate reported no differences in coffee samples, while the group without chocolate was able to detect differences.

Analysis: The argument assumes that the chocolate is the only relevant difference between the two groups. To weaken this, we should look for an alternative explanation for why the first group couldn't taste the differences. Perhaps the first group was composed of people who aren't coffee experts, or maybe the coffee samples they were given actually were identical, unlike the samples given to the second group. Always be suspicious of small sample sizes and potential differences in the subjects themselves.