You seem to be confusing rationalisation with rational thinking. Rational thinking involves making logical deductions from a set of objectives and constraints

You seem to be confusing rationalisation with rational thinking. Rational thinking involves making logical deductions from a set of objectives and constraints to determine what actions to take. Ideally some of the constraints will be ethical, and perhaps some of the objectives will be emotional. Rationalisation involves coming up with reasons to justify a decision that has already been made for other reasons. Perhaps the real reasons do not satisfy the person's conscience. Perhaps the real reasons will not persuade other people. Perhaps the real reasons are emotional and not rational. But the process of inventing these reasons is not allowed to challenge the original decision.