There are actually two slightly different ideas that are called UBI. The libertarian variant is a relatively small guaranteed income (usually roughly the curre

There are actually two slightly different ideas that are called UBI. The libertarian variant is a relatively small guaranteed income (usually roughly the current minimum wage), is usually paid for with a VAT or sales tax, and replaces most or all of the current welfare programs. The main objectives are to provide a safety net for the poorest citizens in a fairer and less bureaucratic manner and to somewhat equalize the bargaining power between low-wage workers and their employers, usually as an alternative to unionization. The socialist variant is significantly larger (living wage), is usually paid for with graduated income or capital gains taxes, and supplements rather than replaces the existing welfare programs. Its main goals are to provide a direct mechanism for income redistribution and to facilitate non-profitable professions (artist, full-time volunteer, professional student, stay at home caretaker, etc.) for those that want or need them. There's obviously a lot of overlap between the two, and most proponents support both sets of objectives to some degree. That said, most of the contentious arguments seem to derive from critics either not understanding the difference between the two proposals or strawmanning their interlocutors into one extreme or the other.