I agree. Absolute certainty about knowledge is impossible, or at least all claims to knowledge could, in principle, be mistaken. Therefore we as humans cannot establish truth. We can however, for the purpose of establishing societies, agree to pretend certain things are true, so that we can move forward. In that case we must also agree to change our definitions when evidence leads us to discover that they are in error.
"There are no facts, only interpretations"- Nietzche