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Difficulty: MediumForming Contrapositives

Under the newly drafted guidelines for experimental therapies, a novel neuroprotectant drug can be granted expedited regulatory review only if it demonstrates a statistically significant reduction in cellular degradation and does not trigger severe autoimmune responses in the test cohort.

Which one of the following logically follows from the guidelines described above?

  1. A
    If a novel neuroprotectant drug demonstrates a statistically significant reduction in cellular degradation and does not trigger severe autoimmune responses in the test cohort, it will be granted expedited regulatory review.
  2. B
    Any novel neuroprotectant drug that is denied expedited regulatory review must have either failed to demonstrate a statistically significant reduction in cellular degradation or triggered severe autoimmune responses in the test cohort.
  3. Any novel neuroprotectant drug that either fails to demonstrate a statistically significant reduction in cellular degradation or triggers severe autoimmune responses in the test cohort will be denied expedited regulatory review.Answer
  4. D
    A novel neuroprotectant drug will be granted expedited regulatory review as long as it does not trigger severe autoimmune responses in the test cohort.
  5. E
    Any novel neuroprotectant drug that either fails to demonstrate a statistically significant reduction in cellular degradation or does not trigger severe autoimmune responses in the test cohort will be denied expedited regulatory review.

Answer

The statement concluding that a drug will be denied expedited regulatory review if it either fails to demonstrate a statistically significant reduction in cellular degradation or triggers severe autoimmune responses in the test cohort.
The stimulus establishes a conditional rule where expedited review (the sufficient condition) requires two necessary conditions: demonstrating a significant reduction AND not triggering severe autoimmune responses. The valid contrapositive is formed by reversing the arrow and negating both sides. Applying De Morgan's laws, the negation of an 'AND' statement becomes an 'OR' statement, meaning the failure of EITHER necessary condition guarantees that the sufficient condition (expedited review) cannot occur.

Step-by-Step Solution

1
Diagram the conditional premise provided in the stimulus.
Expedited Review → (Significant Reduction AND NOT Autoimmune Responses)
Identifying the sufficient condition (Expedited Review) and the necessary conditions (Significant Reduction, NO Autoimmune Responses) is required for formal logic deductions.
2
Form the contrapositive by reversing the conditional relationship and negating both sides.
NOT (Significant Reduction AND NOT Autoimmune Responses) → NOT Expedited Review
The contrapositive is the only logically valid deduction that can be drawn with certainty from a basic conditional statement.
3
Apply De Morgan's laws to simplify the negated necessary condition.
(NOT Significant Reduction OR Autoimmune Responses) → NOT Expedited Review
When negating a compound 'AND' statement, it becomes an 'OR' statement, and each individual term is negated (negating 'NOT Autoimmune Responses' becomes 'Autoimmune Responses').

Key Concept

Forming Contrapositives and Applying De Morgan's Laws
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Topics

Forming Contrapositives

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