Logical reasoning PrepTest 140 · Section 2 · Question 20

Correct. Argument or Facts:
Argument

Valid or Flawed:
Flawed

Question Type:
Strengthen with Necessary Premise

Stimulus Summary:
Data shows that food prohibitions served an important role in ancient cultures, but those cultures didn't have that data, so it can't explain their origins.

Answer Anticipation:
This argument appears more difficult than it actually is because the subject matter (and underlying assumption) is very high level. However, as with many Strengthen with Necessary Premise questions, we can start with any new terms in the conclusion and work backwards.

Here, the entire conclusion is essentially a new term. There's no reference in the premises to what can and cannot serve to explain the origins of something, just a note that the available data wasn't available to those who implemented certain prohibitions.

So the assumption of this argument is just the connection of the premise and the conclusion—if data showing the usefulness of a practice wasn't available to those who implemented it, then that data can't explain the origins of that practice. Any answer that draws this connection will serve as a correct answer.

Answer Explanation:
This answer establishes the missing connection between the premise and conclusion. If the origin of a food prohibition can be explained without relying on just what the people who adopted it understood, then the modern data could potentially be used to explain these origins, thus completely undermining the argument.

Key Takeaway:
At their heart, every argument's assumption boils down to, "If {premise}, then {conclusion}." When you're completely lost, start there and see if you can note the shift between those elements that makes the conclusion invalid.

Incorrect. There's no discussion of "contradictory" food prohibitions, so this answer is out of scope.

Incorrect. Nutrition is out of scope of the argument. While it arguably falls under the category of medical functions, the argument doesn't rely on those medical functions being nutritional.

Incorrect. The original purpose doesn't need to be forgotten so quickly in order for the argument to work—since these cultures were ancient, it could have taken more than a few generations. The original purposes could even still be known by the cultures using them, with scientific data reinforcing this cultural knowledge.

Incorrect. These original adopters could have understood the medical purposes behind the prohibitions. They didn't have access to the same data as modern researchers, but they could have had access to other data that allowed them to reach the same conclusion.