Here is Peter Costello explaining Tony Abbott’s broken tax promise:
he increase in the top marginal tax rate has sailed through the Parliament with Labor support. It was the largest revenue measure over the forward estimates, but as a political measure it has not been successful. The idea was, so it was said, that if the Liberal Party compromised one of its core principles and supported higher income taxes, then the Labor Party would compromise one of its core principles and support lower spending. In fact no such thing has happened. The tax increase has gone through and the expenditure reductions are facing stiff opposition. Higher taxes have not brought any lower spending.
He seems underwhelmed by the logic.