In an earlier paper I outlined a proposal for a national income insurance plan and discussed the strengths of the approach (Williamson,1974c). Income insurance is a special case of the negative income tax or more generally of the guaranteed income. Negative income tax proposals of any kind are open to a variety of criticisms from both the left and the right. The national income insurance plan is no exception. In the present paper an attempt is made to anticipate and deal with the major arguments against the plan. Many of these arguments are equally applicable to other guaranteed income proposals. For this reason the paper is in large measure an evaluation of the major arguments against the guaranteed income approach to income maintenance.