He just means that if we slowly switched over the a Basic Income by ratcheting up payments, rather than as a big one off change, would this mitigate the incentive to just quit work? So for example, if I got an extra $2k per year from the government, I probably wouldn't change my attitude to work. If I got an extra $2k increase every year for 5 years, so that at the end of 5 years I was $10k per year better off than I am now, this might reduce the incentive for me to avoid working more, compared with if I just got $10k extra in year 1.