Turn retirees into cannon-fodder. It's some kind of pension, I guess...
Old Man's War
Another semi-classic which I managed to miss. Still wondering if 75 is a good age or not. Still wondering if I'll ever make it.
Interesting take on using senior citizens as canon fodder, though the second half of the book is less conceptual and more like regular military SF.
The Ghost Brigades
This sequel to Old Man's War received a cooler reception, but in some ways it's a lot like it's predecessor and follows the same structure. The first half is exploration of a concept, this time, instead of transplanting a senior mind, it's about breeding (super)soldiers without a mind, and their relation with regular humans (as far as genetically modified soldiers are regular humans).
And just like the first book, the second half is more military than conceptual. I still liked it though.
There are a few more novels / stories in the same universe. I think I must have read one or two, but cannot recall them right now. Sorry.
Dapper / TellTales! 73