I am not sure I understand the difference between logical and rational here but what I meant by rationalization was as a psychology term describing one of the defense mechanisms (i.e. denial, projection, rationalization, etc) - as one of the ways we lie to ourselves. Perhaps it is where the emotional center uses the intellectual center to make up "reasons" (is this what you meant about the rational taking up the slack of the logical?)... in this sense, having higher intellectual skills could just make one a better liar.