Why did Adam Smith oppose mercantilism and government monopolies?

Adam Smith opposed mercantilism and government-granted monopolies because he believed they inhibited economic growth and prioritized the interests of a few over the welfare of society. In his seminal work, An Inquiry into the Nature and Causes of the Wealth of Nations, Smith argued that national wealth grows best through a system of "natural liberty," where competitive markets allow individuals to pursue their own self-interest, which inadvertently promotes the public good.12

Smith’s critique of the "mercantile system" centered on several key points:

• Distortion of Competition: He argued that mercantilist policies, which favored monopolies at home and abroad, prevented the competitive system from functioning effectively.1
• Protection of Privilege: Smith viewed government-sanctioned monopolies as instruments that protected the "mean rapacity" of merchants and manufacturers rather than serving the broader public interest.1
• Inefficiency: He maintained that trade is mutually beneficial and rejected the mercantilist notion that a nation can only grow rich at the expense of another.32

Ultimately, Smith advocated for laissez-faire capitalism, believing that free enterprise, rather than government-constrained regulation, was the most effective engine for increasing productivity and national prosperity.415