Mercantilism, the dominant economic theory guiding early modern European states, treated global wealth as essentially fixed, meaning one country's gain from trade necessarily came directly at another country's expense. That zero-sum assumption justified colonial trade monopolies and protective tariffs as sensible national policy, and it was only gradually displaced by a very different idea, foundational to early capitalism, that voluntary trade could genuinely create new wealth for everyone involved rather than simply reallocating a fixed total amount between winners and losers.
Mercantilist policy followed directly from its zero-sum view of wealth
Mercantilist theory measured national wealth primarily in terms of accumulated bullion and precious metals, and treated global trade as a fundamentally zero-sum contest, one nation's trade surplus was necessarily another's deficit. Colonies existed within that logic specifically to supply raw materials cheaply and to buy the mother country's manufactured goods exclusively, and protective tariffs and trade monopolies followed directly and sensibly from that same underlying zero-sum assumption, since letting wealth flow freely to a trade partner was understood as a direct national loss.
Early capitalist thought undermined mercantilism's core assumption directly
Economic thinkers increasingly argued that voluntary trade between parties could genuinely create new value for both sides at once, rather than simply moving a fixed pool of existing wealth around between them, a specialised producer trading freely with another could leave both genuinely better off than either would have been in isolation. That argument directly undermined mercantilism's core zero-sum premise, and gradually, over an extended period, shifted economic policy toward freer trade and private capital accumulation as the primary engine of national wealth, rather than state-controlled monopoly and bullion accumulation.
What we're still unsure about
That mercantilism rested on a zero-sum view of trade, and that early capitalist thought challenged that premise directly, are well established, extensively documented facts of early modern economic history. What's more genuinely a matter of ongoing historical debate is exactly how sharp or gradual the real transition from mercantilist to more free-trade-oriented policy actually was in practice, since many nominally free-trade-era states retained substantial protectionist measures well into the industrial period, meaning the shift in economic theory and the shift in actual state policy didn't necessarily move together at the same pace, and historians continue to actively debate how to characterise that lag.
This sits inside Mercantilism & Early Capitalism, one of seven topics in Economic History, one of seven domains in History, one of seventeen subjects the app can quiz you on.