Many ancient philosophers believed that human beings were fundamentally rational creatures, capable of discerning truth through logic alone. Modern cognitive science, however, reveals the pervasive influence of cognitive biases and emotional reasoning on even our most considered judgments. The author's primary purpose in the passage is to:

The correct answer to the question "Many ancient philosophers believed that human beings were fundamentally rational creatures, capable of discerning truth through logic alone. Modern cognitive science, however, reveals the pervasive influence of cognitive biases and emotional reasoning on even our most considered judgments. The author's primary purpose in the passage is to:" is Option C: challenge a traditional view with contemporary scientific findings..

The other options — A) argue against the relevance of logic in human decision-making., B) demonstrate the historical evolution of philosophical thought., D) advocate for a return to purely rational modes of thought. — are incorrect for this GRE Exam Prep question. As explained above: The passage presents a "traditional view" (ancient philosophers) and then introduces "modern cognitive science" to reveal conflicting findings, thereby challenging the earlier belief.