The issue is that the mercantilism mechanic and detailed ins and outs isnt explained at all in EU4 while in EU3 it was very obvious what the slider did. Im still wondering if your merchants in EU4 perform better abroad if you have less mercantilism , just like the EU3 mechanic.
It is really simple, and the tooltip explains it. It is just a boost to provincial trade power, the trade power you get from provinces. That is the only thing it effects, and there is no more to understand.
In the game files it says:
Code:
mercantilism = {
global_prov_trade_power_modifier = 2.0
}
Though no doubt there are hidden events triggered by certain levels in it, the same can be said for every other value/idea in the game.
I am perplexed by how many people having problems understanding trade, since it is fully explained in game, unlike some other mechanics.