That inner critic is not something innate that everyone has. You learned to have it inside you. Someone taught you, either directly or indirectly, that you have to criticize yourself in this way.
Who taught you that?
It will be very helpful for you to talk with the person who taught you that you need an inner critic. It might be a parent or a teacher, or someone else very close to you like a sibling or other type of care-taker. This person doesn't need to be alive. You can talk to the cartoon version of them - the version that lives inside you.
Once you have an audience with the cartoon version (inside you) of the person who taught you to have an inner critic, you can ask them a very important question.
Why do I have to criticize myself?
The answer may surprise you. You were led to believe that self criticism is important, valuable, and necessary for some reason. Find out what that reason is. Then, question it.
If you determine that the reason is that self-criticism protects you from bad things happening, for instance, you can question the wisdom in that belief. Does it really work this way?
Then, you can ask yourself if you are willing to live without self-criticism even if it turns out that it is important, valuable, and necessary. Are you willing to go without it and suffer the possible consequences? This part will probably feel dire, and scary or sad. Like you are bidding farewell to a person you love, whom you may never see again.
If you are willing to live without self-criticism, and you mourn the loss of self-criticism and all it provides for you, then you will immediately be able to stop doing it. The voice will go silent forever.
If you find the inner critical voice still has volume, then it means you aren't willing yet. Check back with yourself in a few days and see if you are willing then.
This question originally appeared on Quora - the place to gain and share knowledge, empowering people to learn from others and better understand the world. You can follow Quora on Twitter, Facebook, and Google+. More questions: