Evelyn,  
It is well known that Milton Fredman argued for a negative income tax in   
Capitalism and Freedom (1962). But I recently came across a simlar   
suggestion by George Stigler in "The Economics of Minimum Wage   
Legislation," AER 36 (June 1946). Stigler wrote, "There is great   
attractiveness in the proposal that we extend the personal income tax to   
the lowest income brackets with negative rates in these brackets" p. 365.  
  
Dan Hammond