Acommon economic argument in support of fair trade states that trade restrictions ensure the economic prosperity of all trading partners. what might be a rebuttal to this argument from someone who is an advocate of free trade?

Free Trade is favorable to countries that have control over capital. Small and medium enterprises have to strive harder to penetrate the market.
Huge competitors can dictate the prices of their product and affect the market because of monopoly. Trade restrictions favor for those capitalist nation whose technology are advanced and can do massive production. 

The answer is plasma :)