Rationalization is coming up with a good reason for something happening usually after the fact. It wasn’t why the person really did something, but it sounds good. It is also a way of explaining something away. It usually doesn’t begin with, “Honestly….” It is something that lawyers, usually, know how to do or politicians. I am not to sure that scientists don’t do it too when they have some results in their experiments that they didn’t expect and/or don’t exactly fit their theories.
Once the rationalization is given, it is expected that it will be accepted and no further explanation will have to be given. The person who gives the rationalization often does such a good job that he or she begins to believe it too and no longer feels that there was a problem with what happened that needed to be explained away to begin with. Once a person has done this, it is very difficult or impossible to convince them otherwise and get them to admit to what really happened.
Salesmen and debaters are good at this. Salesmen often sell a product that they don’t necessarily believe in especially before they become a salesman for that product. Salesmen have to do a convincing job of getting people to believe that the salesmen have a product that they, the prospective customers, can’t do without. Debaters practice taking both sides of an issue and proving that the side that they are taking for the sake of the debate is the correct one.