Final answer:
The fundamental element of supply-side economics is marginal tax cuts, which aim to stimulate economic growth by incentivizing work and increasing the supply of goods and services.
Step-by-step explanation:
A fundamental element of supply-side economics is marginal tax cuts. This approach argues that reducing income tax rates and other taxes would lead to an increase in labor supply as people would be incentivized to work more, knowing they would keep a larger portion of their income. Supply-side economics, a term closely associated with the policies of President Ronald Reagan in the 1980s, holds that such tax cuts can potentially increase overall economic productivity and even tax revenues, through greater economic activity.
The increase in the after-tax real wage is supposed to encourage more labor supply, which in turn increases the production of goods and services. This diverges from the view that stimulating aggregate expenditure primarily increases real GDP, focusing instead on increases in potential output. Supply-siders believe that over time, the positive effects of tax reductions on work incentives and productivity could offset the initial decrease in tax revenue.