One small G20 snub by the U.S., one big blow to the world as we know it

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Open this photo in gallery: Seating signage for the U.S. delegation is displayed ahead of the opening plenary session of the G20 Finance and Central Bank Deputies Meeting at the Cape Town International Convention Centre, in Cape Town, South Africa on Feb. 24.Nic Bothma/Reuters John Rapley is a contributing columnist for The Globe and Mail. He is an author and academic whose books include Why Empires Fall and Twilight of the Money Gods. Convening a G20 Summit without the Americans is like holding a papal conclave without the pope. Yet here we are. South Africa this year assumed the rotating...