How can a basic income be defended?

Following the submission of 125,000 signatures collected by organizations (including BIEN Suisse) supporting the establishment of a basic income, Swiss citizens will vote in a referendum on a popular initiative to include the principle of an unconditional basic income in the Swiss Federal Constitution. While a basic income, which is defended by Vanderborght and Van Parijs (2005) under the term "universal allocation", can take many forms, its principles are that it is paid (1) on a universal basis, in an equal amount to all 3, without testing for means or needs, (2) on an individual basis and not to households, and (3) unconditionally, without requirement of any counterpart. It can be defended from both a liberal-libertarian perspective as a replacement for existing benefits and social insurance (with Friedman often cited in this sense, although his negative tax proposal is fora family-based system; Capitalism and Freedom, p. 159),or from a progressive standpoint, in which case the basic income would be added to most existing benefits and social insurance. It is more in this second sense that the BIEN (2013) advocates a basic income, although the liberal aspect of the measure is also assumed: "It's the most liberal solidarity principle one can get, as it ensures individual existence and social cohesion, without the rigidity of interventionism and no oppressing bureaucracy." A progressive version would add a fourth characteristic: it must be (4) in an amount sufficient to cover basic needs and enable participation in social life.