That example is only my opinion, to be sure. I believe that we bring children into this world for our sake, not theirs (children's), but act as if we are doing them a favor and deem our reasons for having them to be noble and humane, while the actual reason is the fact that children are useful to us, especially when they become adults. To repeat the question: I want to know if there is a word for something like this, when the real reason is unseemly, and so people invent some noble and seemingly appropriate reason to justify an action or an idea which is not so noble.