The constitution gives Congress the authority to tax and spend for the general welfare, and that includes welfare in the more specific modern sense. I support having about the current amount of welfare spending, but it should be considerably simplified.
I like the idea of Universal Basic Income, but the tax rate needed to give everyone $1000 a month would be too high. I propose instead to have a smaller basic income funded by 3 different sources, each paid quarterly so that people would receive one check each month. I'd replace the standard deduction with a $3000 tax credit with $2400 refundable, which would mean a six hundred dollar check every three months. I'd implement a tax on carbon and other mining to pay the second quarterly check, The third quarterly check would be funded by corporate taxes or a sales tax. Each of the latter two payments would vary depending on revenue, but would aim for an average of $500 a quarter. These payments would go to all adult Americans, and children would be provided for by implementing Romney's 2020 Family Security Act, which pays a monthly child tax credit of 250-350 per child, and pays for it with cuts to other welfare programs.
Sen. Romney's Child Tax Reform Proposal Aims to Expand the Social Safety Net and Simplify Tax Credits/
This basic income would replace most welfare programs, but there should still be some housing assistance in large cities, food banks, disability support, and some unemployment insurance, though at lower levels than currently since they would just supplement the regular monthly checks rather than support people by themselves. Most other means tested welfare, like SNAP, TANF, and WIC, would be abolished.
Social Security should be gradually replaced by the Homestead Capital Act, a program that would give everyone the borrowing power to use loans to buy stocks whose proceeds would first pay off the loan, then pay everyone's retirement.
The Capital Homestead Act: A Plan for Getting Ownership, Income and Power to Every Citizen