Rationalization is because of brain structure.

people have (a fast response brain) amygdala and (a thinking brain) the prefrontal cortex.

the amygdala does fast what you did previously(is like a “cache” system in computers). amygdala takes internal state and external state and selects an action that that is done previously that will most likely result in most satisfaction the fast way. like one to one correlation. the prefrontal cortex takes the response from the amygdala and the state and searches similar things in the long-term memory like many to any correlations.

amygdala responds 10 times faster than the prefrontal cortex. they start at the same time, one returns earlier and one returns later. it is because of the number of levels of layers of neuron cells. the amygdala is made of with minimal amount of layers. the prefrontal cortex is made of several layers of neurons.

amygdala works well if the situation did not change. and makes mistakes if the situation is changed.

so frequently people do mistakes then they think.

so rationalization is because of the design of the brain.

it is a habit to not wait for the slower brain to respond.
you can easily wait a little bit, always.
I have a habit to search for ideas than to think about them, it helps to think better. and if I catch myself doing the opposite I don’t lie to myself and true to myself that I acted fast that was thinking and it was bad.

the prefrontal cortex is blocked when people have low energy(to conserve energy) or high on dopamine or high adrenaline (to enable fast action). the blood vasels shring in response to cortisol. so people frequently do not think.

it takes some caution and intention to maintain the state of arasul of amygdala.
to make it low on dopamine or adrenaline beccause of attention taking othings.
to not be hungry, to sleep well and not wait to go to toilet, not to eat too much sugar, not to have fun because for sake of having fake high dopamine, not do something of statisfaction that is because of error like watching tv instead of sleep both result in pleasure. but one does not soleve the actual problem and brings more dopamine.

when dopamine is resolved people feel commness – the homeostatis.