[rubberstamp]

What I meant by 'as long as you have a working brain' is that "you are competent as long as you are willing to do rational analysis on your own and come to conclusions". You are perfectly fit for the office of president so long as you are willing to learn. You do not have any inherent limitation. Even most of the economists do not know what they are talking about. Most mainstream economic theories are not even proven to to be correct. Its just like anyone willing enough to learn to code can eventually write beautiful and accurate code so long as they remain enthusiastic learners.