Mercantliism - defined

Mercantilism ended in late 1700s, it is an economic philosophy that held that it was essential for a nation's welfare to accumulate a stock of precious metals.

These metal's were gold and silver, and in the Mercantilists view, was the only source of wealth. Lastly, to increase a nations wealth, government policies should promote
exports and discourage imports.
An example, of modern day mercantliism is the heavy state intervention of the Frances socialists.

[jmitterii]

All countries at present are engaging in a form of mercantilism.
The different from past mercantilism is the mostly abandoning of accumulating metals or other commodities for wealth accumulation. And instead of necessarily up front banning imports, it is propping up usually via tax credits, deductions, and direct subsidies particular businesses for the added purpose of export. Modern mercantilism has also become creative in that its using the concept of foreign direct investment as a means to establish supply production, but with the intent mostly to export those products from the country that receives the foreign direct investment. Often its to take advantage of national political differences that provide a difference in standards of living various share of productivity of productivity ratio to income strata.
The eventuality of mercantilism occurs under a supply side strategy that disregards the demand side all together.  With heavy supply subsidies, which eventually diminish domestic demand capacity, requiring new markets as suppliers can't find enough buyers.  In the long run, all nations begin attempting to export their way to prosperity. In doing so, the nations find themselves in a deflationary pressures which tends to require currency devaluation in attempt to compete in more foreign markets to find more capable demand.  Also encourage even more tax deductions for suppliers and various other direct subsidies for chosen industries to assist in competing other foreign markets.
The disregard to domestic markets in the long run lowers that standards of living for vast majority causing a deflationary trap. This vicious cycle continues.  Mid run benefits are to a very small select few who control monopolies, oligopolies, and monopsonies.  The constant requirement of increase subsidies for various businesses entrenches government and business elites where they become, if the two aren't already, indistinguishable.   It overrides Keynesian economic theory since modern mercantilism we see today disregards domestic markets to which productivity gains through active subsidy for investment in R&D and during times of low domestic business cycles distribute productivity in virtuous cycle that increases demands ability domestically.  
Modern day mercantilism is a disaster in the making as such fighting over economics will likely lead to domestic instability in crime rates, riots, potential rebellion, as well as possible war with other nations.