
But how and when they are ignored or followed is, inescapably, a matter of judgment for politicians, not one of obligation. Judgment of the situation is the essence of the politician's job; the successful politician is the one who gets it right more often than wrong.
The same might be said about business. Business is by no means a smash-and-grab affair,
a game for 'a pack of crooks'. But neither is it a game for the naïve or the
saintly. To succeed, you have to know the 'rules' - or the lack of them. That
is why successful business people are said to have a natural 'instinct' for
business while others simply cannot get it right. Judgment, not ethics, not
intelligence, nor even diligence, rules.
In the present case, Ms Zille, widely seen as a highly professional and principled politician, committed an error of judgment with her initial tweet. There was nothing extraordinary about that; we all make mistakes and very many of them are made in a careless moment on the internet.
But in her response she has probably
made it a terminal mistake. She has set herself against the party she has
played a leading role in building, which is to say she has divided it, and plunged
its black leader into a terrible dilemma that was none of his making but
which he must now address because it is his job.

These arguments will continue,
of course, and so they should. I am interested above all in how politics shapes things, not in declaring who is in the right. All of us will see in time the one if not the other.