Rationalization is a process by which you reason an opinion. In a normal decision making process, you reason to arrive at an opinion whereas in rationalization, you arrive at an opinion first and reason your opinion later. Rationalization happens when you validate opinions based on how they make you feel instead of applying reason. You accept comfortable opinions and reject uncomfortable opinions. For example, if someone tells you that you are selfish, you reject that opinion because it feels uncomfortable. Instead, you hold the opinion that you are selfless as it feels comfortable. To convince yourself that you are holding a correct opinion, you rationalize. You recollect evidences of selfless behaviour from the past to prove that you are selfless.You ignore evidences of selfish behaviour by rationalizing them as irrelevant. You label them as mistakes or blame others for your selfish behaviour. Rationalization works due to the imperfect nature of opinions. Opinions are conclusions made about reality with insufficient information. No one, including you, can be completely sure that you are selfish or selfless as no one knows you completely. So it is possible for you to accept either opinion. Rationalization makes you less wise. You will miss wisdom about yourself and the world because rationalisation conceals them. For example, if you always rationalize your selfish behaviour, you will miss out on the wisdom that selflessness leads to happiness. To stop rationalising do not evaluate opinions on how they make you feel, use reason.