The detail that weakens your argument may strengthen your trustworthiness if you include it.

An argument with no soft spots invites suspicion, because listeners know real situations have them. Naming the fact that cuts against you shows you have looked at the whole thing rather than the flattering half, and it tells people what sort of account they generally get from you. You lose a little ground on the point and gain a great deal on being believed. That trade is usually worth making.

Before your next case, letter or difficult conversation, write down the strongest objection to your own position. Say it early rather than waiting to be caught with it. Then say why you still think what you think.