I can see benefits to the principle of charity. It helps avoid flame wars, and from a Machiavellian point of view it's nice to close off the "what I actually meant was..." responses.
Some people are just bad at explaining their ideas correctly (too hasty, didn't reread themselves, not a high enough verbal SAT, foreign mother tongue, inferential distance, etc.), others are just bad at reading and understanding other's ideas correctly (too hasty, didn't read the whole argument before replying, glossed over that one word which changed the whole me...
I couldn't agree more to that - to a first approximation.
Now of course, the first problem is with people who think a person is either rational in general or not, right in general, or not. Being right or rational is conflated ... (read more)