How can two diametrically opposed ideas be held in the mind and considered to be equally valid? This is an absurd statement. As Dale Carnegie once stated to be one of his cardinal principles, it is important to try to see things from the other person's point of view. One can try to see things from the other person's point of view without accepting it as equally valid as one's own opinion and should do so as a general principle to maintain intellectual integrity. For an idea to be valid, it must correspond to the real world and how it functions. A valid idea can be employed to make accurate predictions about the future, and successful predictions in turn tend to validate the idea.