The "real freedom" conception of social justice justifies granting each citizen the highest sustainable unconditional basic income payment, constrained by two conditions: respect for every individual's formal freedom, and an appropriate level of resources targeted towards the less able.

This conception is advanced by Philippe Van Parijs, who elsewhere suggests that while the highest sustainable UBI is his ideal, it is more realistic to begin with a smaller, partial UBI, and incrementally scale up the payment amount.

theoretical