"For to change one's mind, or even one's policy, is a confession of weakness. If, for example, Eurasia or Eastasia (whichever it may be) is the enemy today, then that country must always have been the enemy. And if the facts say otherwise, then the facts must be altered. Thus history is continuously rewritten."

George Orwell, 1984

I think more people need to read this book (again). It's more than the short phrases you have heard. Much more.