Genesis 3:11 - And He said, Who told you that you were naked? Have you eaten of the tree of which I commanded you that you should not eat?
By taking the fruit of the tree of the knowledge of good and evil, they found a source of the knowledge of right and wrong outside of God. This can be identified as the principle of reasoning.
They no longer needed the wisdom of God; They could govern themselves according to their sense of right and wrong. This is why God questioned them "who told you?"
They replaced obedience with reasoning.