The notion of social justice has been addressed from the perspective of 'ethical realism' and 'ethical anarchistic'. Here, however, the possibility of 'ethical constructivism' becomes formulated. With departure in Rawls' description of an idealised meeting defining social justice, the initial steps into ethical constructivism become taken. However, idealised meetings become substituted by real-life meetings referring to classroom practices. Social justice becomes interpreted as expressions of hopes and visions for the future. As visions and hopes are tentative, so are any conception of social justice. This observation leads to a new of interpreting mathematics education for social justice.