Logical reasoning PrepTest 153 · Section 3 · Question 7

Correct. Argument or Facts:
Argument

Valid or Flawed:
Flawed

Question Type:
Errors in Reasoning

Stimulus Summary:
A particular cereal is made with whole-grain oats. Experts agree whole-grain oats are healthful. So, most people would have more healthful diets if they ate this breakfast cereal.

Answer Anticipation:
Hang on, what else is in this cereal? If the first ingredient is whole-grain oats and the second is pure nicotine, a bowl full of cereal doesn't sound all that healthful, after all. And why choose cereal as the way to get whole grain oats, when you could just eat plain oats? This is a giant part-to-whole fallacy. Just because one ingredient is healthful doesn't mean the food is healthful. If that was true, it would also be true that a diet of nothing but spaghetti marinara is a healthful diet, since tomatoes are a healthful food (for most people).

Answer Explanation:
Right up front, a perfect description of part-to-whole fallacies. Just because the oats are healthful, doesn't mean the cereal is.

Key Takeaway:
Just because a part of something has a certain property doesn't mean that property can be properly ascribed to the whole, and vice versa. A team can have the best player in its league without being the league's best team. And just because a team is #1 in its league doesn't mean that every one of its players is the league's best at their position.

Incorrect. This isn't the right fallacy. Oats as an ingredient are neither sufficient nor necessary to make a food healthful.

Incorrect. The stimulus used the term "healthful" consistently. The problem was, it played fast and loose with how a single healthful ingredient affects the healthfulness of a food.

Incorrect. This answer falsely accuses the stimulus. Nobody said healthy people tend to eat this cereal.

Incorrect. This exact answer choice is a common trap answer on flaw questions. It describes circular reasoning. Don't choose it unless you're sure you're seeing circular reasoning. (Here's a handy memory device: "Circular reasoning is circular reasoning because circular reasoning is circular reasoning.")