Running Mercantilism

[cabert]

I use merc in all the situations described by iranon + whenever I've been slow with GP generation.
the extra GPP will help greatly.
I tend to have vassals very often, and thus like the merc bonus and don't feel the merc penalty much.

 

[noto2]

Mercantilism can be handy in the right circumstances. The AI is inordinately fond of it; I've had games where every other civ ran Merc for a long time, thus cutting off all my foreign trade routes. In those circumstances, if you can't beat 'em, join 'em--especially if you're spiritual and can make the change without anarchy. Using the free specialist as a merchant should help make up for some of the lost trade route income.

This is exactly it. Like real life, your own trade policy needs to reflect what your (potential) trading partners are doing. If everyone has open trade, being in free market might give you the highest boost, but if everyone is in mercantalism, then the cost of mercantalism - loosing foreign routes - is reduced to zero. You need to think about many things. When I'm playing a game as a relatively small or average sized civ with no vassals, free market gives me a very big boost. But if I'm a large empire with many vassals, free market gives me a very relatively small boost, and it gives my rivals a relatively big boost, so mercantalism might be a better option, especially when state property is not available.