Nothing can be known for sure under postmodernism. Any statement might be true. There is no court of appeals. Fortunately, postmodernism is ultimately self-refuting. We don't, and cannot.
Postmodernism is a metaphysics which denies the validity of metaphysics.
Because of this self-contradiction, we can safely ignore postmodernism. The high court of appeals is our appreciation of being an individual subjectivity in a group of similar subjectivities. Use the BACK button on your browser to return to where you were.