Global taxation would be a top down system, while free trade is nothing more than capitalism applied internationally. In other words, free trade is not something imposed by a world government, but the opposite. It means merely that businesses and individuals are allowed free use of their own capital.
That being said, the whole question of free trade is kind of academic, since it can only exist between free countries with free markets, and there are not very many of those.
Additionally, IMO, the question of national security has to be looked at - farming out all our heavy industry to foreign countries makes us vulnerable.
However, I do believe that free trade is generally beneficial for the same reasons that the free market is beneficial.
In free trade, capitalism is used to subsidize economies that would otherwise fail if left to their own markets.
In other words, free trade is not something imposed by a world government, but the opposite. It means merely that businesses and individuals are allowed free use of their own capital.
How so? Free trade organisations and treaties are the stepping stones to world government.
Free how? Try buying an American made tv, vcr, windshield wiper, spark plug, asparagus, etc. Nobody uses those items anymore, right? On top of losing the freedom to buy those American made goods, now those former workers are free to work at WalMart. Hooray!