The idea has merit but unfortunately blurs the issues of income redistribution and state power. As with many public issues, if the state administers the program, the result will likely be a catastrophe. The evidence? The outcome for prior programs of this kind.
Warren Buffett has recently argued that he and other very wealthy people should pay more in taxes, a sentiment many other wealthy people share:
http://www.nytimes.com/2012/11/26/opinion/buffett-a-minimum-...
Quote: "... we need Congress, right now, to enact a minimum tax on high incomes. I would suggest 30 percent of taxable income between $1 million and $10 million, and 35 percent on amounts above that."
But this realistic proposal, and the idea of a guaranteed income, differ in one important way -- the former is being proposed by people able and willing to take action on their own, which they have:
http://en.wikipedia.org/wiki/The_Giving_Pledge
But the latter guaranteed income idea would be administered by the state, which means it would be subject to ever-changing political forces. It would be a shame if a good idea were administered by an entity renowned for doing things so badly that even good ideas can be made to look terrible in retrospect.
As tokenadult remarks in a post here, it's never been tried, anywhere. On that basis alone, it deserves a hearing. But it would be a shame if the power responsible for its implementation guaranteed the failure of a potentially successful policy.
Am I unjustly skeptical of big government? I don't think so. Examples abound that show how inefficient and counterproductive big government can be -- NASA compared to private space companies, government welfare programs compared to those administered by private agencies. But my favorite example is that, six months after the 9/11 attacks, the INS approved student visas for two of the dead terrorists so they could enroll in pilot training:
http://www.nytimes.com/2002/03/13/us/nation-challenged-hijac...
This example redefines "clueless" and is hardly atypical. I would hate to see a sound public policy idea undermined by the method of its implementation.