Classical distribution theories distinguish between that part of the annual product which is necessary for its reproduction (including necessary subsistence for workers and replacement of the means of production) and the remainder (the ‘surplus’), and seek to explain the size of the surplus and its distribution among classes. They do not view the real wage rate and the rate of profit as determined by the relative scarcity of labour and capital; rather, one of the two distributive variables is explained independently from both the social product and the other distributive variable, and the other is determined as a residual.