Although some university departments like to call it "political science," it is at least as much an art, calling for intuition as well as systematic study.  Sometimes there are cases when a government seems able to do no right.  Even though some of its individual initiatives and responses might seem worthy, it seems unable to get its act together.  Observers can smell decay in the air.  It happened with the government of Harold Macmillan, that of James Callaghan, and that of John Major.  It is happening again.

Partly these governments were past their sell-by dates and had been too long in office to react with fresh awareness as governments need to do.  In quick succession Gordon Brown has presided over his Chancellor's disastrous and much-derided budget, his defeat over the rights of Ghurka soldiers to live in the country they fought for, and now his humiliating climb-down on MPs expenses. 

Commentators can recognize the signs by instinct.  They have seen it before and they know what it means.  It represents the erosion of authority.  People have decided that Gordon Brown has no future and will therefore be able to deliver no goodies.  They look elsewhere for prospects of promotion and reward.  The power of patronage ebbs away.  This government is headed for ignominy and oblivion; commentators have seen it too many times to need scientific studies to tell them that.