[ 'You're probably right' would be the smart-yet-unwise answer to such a statement. Yoda had had enough faith in Obi-Wan to kill Anakin when the moment arose. But there was only one problem...]

I could not do that, because Anakin Skywalker was already dead. [ The response comes out calmly. ] And I for one did not wish to add the destruction of another Sith Lord to my name.