A rationalist who doesn't consider the effects of tone when attempting to effect a change in someone's thinking is not dealing in reality. There is a reason Becker's Rules have to be asked for and agreed to, even among rationalists- we are not built to automatically separate tone from content, and there are times when even the most thoughtful of us are personally vulnerable to a harsh tone. We tend to simplify to "two Beysians updating on evidence", but in reality, we have to consider the best way to transmit that message, as well as the outcome of that transmission. Human language is not tightly controlled code- when a change in tone is equivalent to a change in meaning, ignoring tone is the same as ignoring all parentheses in code.