The principle of the Independence of Irrelevant Alternatives (IIA) says that the choice between A and B should not depend on whether or not other options, such as C, are on the menu. If you prefer A to B, then your preference should be unaffected by the presence or absence of C.
This seems pretty commonsensical. Imagine you're in a restaurant and you're offered the choice of apple crumble or ice cream for dessert and you choose apple crumble. Now suppose the server tells you that they have a chocolate cake too. You might happen to prefer the chocolate cake, in which case you'd change your order, and that would make sense. But if you were to say 'In that case, I'll have the ice cream' we'd think there something pretty odd about your choice.
Yet it seems that Alex Mccarthy, writing at Give Me Sport, is not a fan of IIA. He criticises the Goal of the Season shortlist for omitting Giroud's scorpion kick against Crystal Palace, on the grounds that it didn't win Goal of the Month (being pipped by Andy Carroll).
Well, if Carroll's goal was better than Giroud's - which was what was decided in January - then there's no chance of Giroud's winning Goal of the Season. The Goal of the Season shortlist is not necessarily the ten best goals of the season, as Giroud's could be better than many of the others that did win Goal of the Month. But there's no point shortlisting a goal that has, in effect, already been eliminated as a contender.