Why only Europe? Why not the entire world?

Re: This is the Common Market Europe Needs, by Iain Martin

Dan Hannan will present the draft statement of a proposed "pan-European Free Trade area open to all states on the European continent."

Wonderful! But why limit the free trade area to European states? Why not expand it to the entire world? Just declare unilateral free trade and go home. You cannot force anyone to trade with you, and those who refuse to trade harm only themselves. This is so simple only politicians cannot see it.