When the Thomas B. Fordham Foundation issued a manifesto about principals a few years ago, I was asked to sign it and I declined. I did so because I don't believe that anyone from any field can be "trained" to be a good principal, and I thought that this was a logical outcome of the views expressed in the manifesto about opening up the job to outsiders. There may be exceptions, of course, there may be an occasional instance of a newcomer who becomes a successful principal, but on average, this strikes me as an unlikely prospect. I prefer to place my bets on people who have shown themselves to be successful teachers and who have had experience as assistant principals. The position of principal ("head teacher") is far too important to turn over to marketing executives, lawyers, business leaders, and other career changers who want a new adventure.
I also disagree with the premise of the "autonomy gap," the assertion that student performance will rise if principals have more power. I am all for giving more discretion to principals to run their schools, with more control of their budget and staff (consistent with due process), but I have never been a believer in the theory of letting thousands of flowers bloom. More likely, a garden that is untended will produce a few flowers and thousands of weeds.
I might be persuaded that I am wrong if the advocates for autonomy could produce data showing a clear link between principal autonomy and higher student achievement. Having seen no such evidence, I conclude that the belief in principal autonomy is based on ideology, not evidence.
Therefore, I dissent.