To contradict yourself is to grow.
In science, it is easy to change opinions because once you have new data you can throw out the old assumptions proven false. Where the opinion is tied to a judgement however, changing opinion is deemed wrong because there appears an unspoken assumption that your power of judgement may be poor if you have to go back on the choices you’ve previously made. That is, of course, nonsense, for to change your opinion based on new information or better understanding is to be honest with yourself and others, and it is the only way to grow.
If you never contradict yourself it is because you are either very wise and never make mistakes, or, more likely, that what you do say is not very important or is not precise enough to be of much value, perhaps partly due to the fear of having to retract your words at a later date should you dare to commit yourself to a strong opinion1. But clinging to a judgement for no better reason than the fear of appearing foolish or attracting the barks of critics is to paralyze yourself and degrade your active mind to a statement of beliefs carved in stone, never to be changed again.
1. It need not be said that the opposite of this, that is to always contradict oneself, is a sign that one either doesn’t value what they are saying or is a hypocrite who uses words to achieve selfish ends. This is not the sort of contradiction I’m talking about here.
– DMITRY FADEYEV