If we assume an economy with a demurrage currency, then Say's Law applies and involuntary unemployment is impossible. Without a demurrage currency, Say's Law is

If we assume an economy with a demurrage currency, then Say's Law applies and involuntary unemployment is impossible. Without a demurrage currency, Say's Law is not guaranteed at all and structural involuntary unemployment is possible even without increases in productivity unless you have a central bank that has to constantly increase the money supply and emulate the demurrage fee with inflation.