“Disagree but don't argue.”
“You want to be a better person? Go listen to someone you disagree with. don't argue with them just listen. It's remarkable what interesting things people will say if you take the time to not be a jerk.”
“They could argue for hours on almost any subject; they usually agreed on broad conclusions, but disagreed on almost every detail.”
“Don't argue about the difficulties. The difficulties will argue for themselves.”
“Argue with anything else, but don't argue with your own nature.”
“It's a strange truth that no matter how persuaded we might be of our own correctness, the discomfiting realization that others disagree with us causes a paralyzing inability to argue the case convincingly.”