“Social Security, Medicare and Medicaid … already exceed 40 percent of the $2.7 trillion federal budget. By 2030, their share could hit 75 percent of the present budget,” writes columnist Robert Samuelson. “To keep federal spending stable as a share of the economy would mean eliminating all defense spending and most other domestic programs. To balance the budget with existing programs at their present economic shares would require … tax increases of 30 percent to 50 percent – or budget deficits could quadruple.”