The key flaw in George Psacharopoulos' argument for charging full-cost fees is that universities do not produce "average graduates". They produce some graduates who earn relatively little during their working lives and some who earn many times that amount.
As graduates benefit all of society, there is a strong argument for funding higher education from taxation of the whole population. To allow for the expectation of higher earnings for some graduates, a contribution could also be sought from a progressive graduate tax.
John Gee, Aberystwyth University.