Logical reasoning PrepTest 145 · Section 4 · Question 23

Incorrect. This argument's conclusion is in a different form. Since the rule is about vaccines, and the example is a vaccine, the conclusion doesn't have to be conditioned on the example falling into the given category.

Correct. Argument or Facts:
Argument

Valid or Flawed:
Valid

Question Type:
Parallel Reasoning

Stimulus Summary:
Intelligent computer → Creative OR Self-aware OR Learn from mistakes
AR3000 Ð not Creative AND not Self-aware
Therefore Ð If AR3000 is Intelligent computer → Learn from mistakes

Answer Anticipation:
This argument establishes a rule that, for something to be true, at least one of three things must also be true. For a specific instance, it rules out two of those things, and then it concludes that, for the thing to be true in that instance, the other must be true.

This is a valid way to argue by ruling out alternatives, and the correct answer should follow the same pattern:

A → B OR C OR D
Example: not B AND not C
Therefore: For example, A → C

Answer Explanation:
Commonly used vaccine → Dead-virus OR Attenuated-virus OR Pure DNA
Vaccine X: not Dead-virus AND not Attenuated-virus
Therefore Ð If Vaccine X is common → Pure DNA
Same structure as the stimulus and, unlike (A), the example doesn't necessarily fall into the group from the sufficient condition of the rule (A/Commonly used vaccine/Intelligent computer), so this matches where (A) did not.

Key Takeaway:
When arguments fall into common patterns—e.g., this argument ruling out possibilities—it can be important to note where common elements fall. Here, noting that the premises ruled out the alternative possibilities and the conclusion established that the example fell into the group that the conditional rule applied to was key in making quick eliminations without needing to diagram everything out.

Incorrect. The conclusion here is where two of the possibilities are ruled out, whereas in the stimulus a premise ruled those two possibilities out.

Incorrect. This answer provides a reason to believe one of the possibilities is ruled out, and then it rules out another in the conclusion—two places it doesn't line up with the stimulus.

Incorrect. In the stimulus, two possibilities were ruled out in the premises. Here, only one is, with the other rules out in the conclusion.