I know it is a popular talking point among conservatives but economics doesnt really work that way. Just like you cant travel to the future you cant borrow from it either.
How it really works is that capital (money) is diverted from where it would other wise go (productive areas) to where the politicians want it to go (social welfare programs).
This continues until the economy has been so crippled by the diversion of resources to unproductive uses that it can no longer support the social welfare state and the economy falls in to decline.
The Mortgaging our childrens future meme also has its counterpoint on the Left Investing in our childrens future when referring to things like government subsidized education.
Both are rhetorical tools that are somewhat misleading. Money exist in the now. It can not be taken from the future and used in the now. If you use it in this place you are not using it somewhere else.
It is the Broken Window Fallacy writ large.
Wisdom
Thanks for link!