Is there a trade-off between inflation and unemployment?
The Keynesian side posits that policies can indeed be used to stimulate demand - demand-side policies - and those markets are imperfect and therefore need priming. The opposing view, from the monetarist/classical side, argues that any intervention by government aimed at stimulating demand beyond the full employment level of output (i.e. LRAS) will be purely inflationary - the trade-off is a SR issue.