Challenging assumptions in decision-making involves avoiding the pitfall of optimizing for the short term while assuming it's beneficial for the long term, understanding that there could be multiple valid solutions rather than a single correct answer, and recognizing the importance of considering the entire system rather than just its individual parts. The discussion also touches upon the concept of the two hemispheres of the human brain working in a complementary manner, where each hemisphere has its unique way of functioning. Emphasizing the need to not let reductionist thinking overpower holistic understanding, the insight highlights the significance of acknowledging the complexity of decision-making processes involving human psychology and behavior, cautioning against relying on assumptions that may seem rational but are often unreliable.