Having discernment is key to gaining and maintaining understanding in Yoga and life.
Unless something has been proven as fact through extensive research, direct neutral experience, and unbiased observation, what you believe is an assumption/hypothesis at the very least or a strong unfounded opinion/belief that has its roots in conditioned popular thought or pseudo-scientific assertion that is subject to the shifting of time and perspective at its worst.
It is important to know the difference between unchanging truth/fact and fiction or biased fantasy while navigating through life, and Yoga, so that you do not adopt prejudices and opinions that cause harm to others or yourself.
Having neutral, scientific discernment is required for holding undistorted knowledge that is free from the consequences of negative karma (thoughts, words, and actions that affect the world). This will keep you free from falsification that prevents you from truly comprehending and seeing what is beyond your ego.
Correct, undistorted, seeing will allow you to most effectively walk your path in truth.