Other theorists use left-libertarian insights without strictly connecting the monetary value of resource value with the level of UBI. Philippe Van Parijs makes a freedom-based argument for the highest sustainable UBI regardless of the value of natural resources, justified partly on the basis that the labor market is imperfectly competitive and produces a significant amount of "job rents." Guy Standing uses many left-libertarian or " Painist" arguments for UBI, along with progressive and social-democratic arguments for UBI without committing to resource- or rent-based financing of UBI.