Why Does David Deutsch Call Misunderstanding Your Fault?

David Deutsch agrees that whenever someone does not understand you, the fault is yours, not theirs, unless they are a golden retriever. He follows the philosopher Karl Popper, and he calls Popper's theory of knowledge streets ahead of everyone else in the 20th century.

Popper is very well known and highly respected. People put him on the list of the 10 top philosophers, and in science they talk about his criterion for distinguishing science from philosophy or from pseudoscience. His actual philosophy is not very well understood. One tenet is that there is only one way of creating knowledge. The details differ, but knowledge created by evolution, by a scientist, by a mathematician, and by a child learning to speak a first language comes from processes more alike than different. The differences are inessential. Learning a new law of physics one has discovered, and learning an existing piece of knowledge from someone else, are the same mental process.

In all of them, the knowledge comes from within the learner. You cannot download it like a computer. You have to guess what the other person means, and at first you will guess wrong.