The metaphor of Paul MacLean's triune brain: his idea that the human brain is composed of three distinct neural systems. At the bottom is the reptilian brain (brown section): an old system that takes over when we are threatened.
Above is a red "mammalian" brain, where strong emotions and impulses are triggered, and all kinds of communicative and social mechanisms operate "below the threshold of consciousness".
At the top is the “neocortex”: the blue brain allows us to think, plan, learn, speak, be attentive to others and have self-awareness.
The development, in MacLean's view, is equivalent to dimensioning this tricolor neuroaxis. But the movement can occur in both directions, depending on how much stress we are experiencing. The calmer we are, the more the blue brain is in control. The greater the stress, the more the red brain takes over. And in emergency situations (real or imagined), the brown brain is in complete control.
When human creatures have a blue brain, asking them why they did something can help them learn how to make better choices. But when they enter the red brain, they act without thinking: their behavior is caused, not done for a reason. Asking why in these situations is more rhetorical than interrogative. And when human beings have brown brains, they are furious, heartbroken, unable to process what we are saying. When a human creature is in this state, we need to change gears from the third to the first: from teaching to appeasement. And try to find out why this happened.
The easy part here is that when a human creature enters the brown brain, the cause is always the same: too much stress. But often the human creature will be dealing with "hidden" tensions: things that are causing him or her to burn a lot of energy without realizing it. And there is always more than one stress involved. The hard part is figuring out exactly what those tensions are.
The basic rule that operates here is: under excessive stress, we regress. We went down the neuroaxis. This phenomenon is true throughout life, but the younger the human creature evolutionarily, the more often and the faster it happens. This is an especially important point for poorly evolved creatures, who want to start their evolution, where they are exposed to a quantum leap in their stress load.
Whatever the age of the human creature, when we ask "Why?" we need to find out which of these "why" we are asking. We may need to reshape the behavior of the human creature. That is, see and understand this behavior in a different way: recognize when it is a stressful behavior and not a bad behavior.