Huh, I've always been suspicious of folks claiming the opposite.
For the downvoters, have you ever tried to explicitly map your externalities?
Having externalities does not mean you are dishonest. Hell, you can even ignore your externalities and still be honest. You can even outright steal from people and still be honest.
What does mapping your externalities have to do with honesty? Is this a poor attempt to suggest that no one can actually be honest because no one has a full understanding of the entire universe? Because that's just a lazy excuse for not trying to be honest and not really worth being in the debate.