Please explain this mathematically utilizing accepted economic models. Otherwise [citation needed]
The fiscal problems we face in the future have less to do with economics than they have to do with basic political science and fundamental accounting principles.
There are two basic facts:
1. The U.S. and many European countries have unsustainable welfare states, with future liabilities dwarfing potential future government tax revenue (short of an extremely unlikely huge increase in GDP in these countries).
2. The political class refuses to acknowledge the facts of part 1, causing them to do nothing about it. Why? Because of the way the political system is set up. Anyone who talks about either massive reductions in welfare benefits or massive tax increases faces political suicide.
Take 1 and 2, put them together and it is quite easy to predict that there are stormy waters ahead. Right now it is a game of Hot Potato. The politicians of the past made promises that the politicians of the future can't possibly keep. A good example was Bush's prescription drug bill, which was passed at a time when it was clear to anyone who cared to check that Social Security and Medicare were (and still are) in big trouble.
Fortunately for Bush, he is now out of office. Woe to any politician who tries to reverse the promise he made to the old folks. Hence, politicians just keep passing the buck along, hoping they can make political gains at the expense of future politicians who actually have to face the music.