PrepTest 151

Correct. Argument or Facts:
Argument

Valid or Flawed:
Flawed

Question Type:
Errors in Reasoning

Stimulus Summary:
3 studies of a new treatment all showed it worked, but they were flawed, so it must not work.

Answer Anticipation:
The conclusion reaches the opposite determination of the study. When the main point is the exact opposite of an opposing point, that's a great hint that you're dealing with an absence of evidence flaw—the author reaching the opposite argument based on a flaw in the opposing point's argument. And that's exactly what's going on here. The studies were flawed, so there's a chance their conclusion is wrong—but the main point of the argument is that the conclusion was wrong, making the opposite true. We need to find an argument that similarly treats a flaw in an argument's methodology as establishing the opposite conclusion is true.

Answer Explanation:
Here, the judges reached a conclusion as to which cake was the best, but there was a flaw in their methodology (different criteria), and so the author reaches the opposite conclusion. That's the same absence of evidence flaw.

Key Takeaway:
An absence of evidence flaw is one of the trickiest concepts to wrap our heads around, as most flaws sound like the problem is an absence of evidence. However, a great hint that you're dealing with one of these flaws is a main point that is the opposite of the opposing point—not just that the other point is unproven or could be wrong, but that it is wrong and the opposite is true. When you see that dynamic, check to see if the author raises evidence for her conclusion or rather relies solely on pointing out a flaw in the opposing argument—if it's the latter, then it's an absence of evidence flaw.

Incorrect. This argument assumes motives based on outcome, which is a different flaw.

Incorrect. This argument features a part-to-whole flaw, assuming that food in a diet lacking nutritional value means that the entire diet is lacking nutritional value.

Incorrect. This answer assumes purpose from a common element, along with throwing in some timeline issues (maybe early scarves weren't decorative).

Incorrect. This answer assumes actual motive based on potential motive, and also has a degree issue ("solely").