Why does Carroll disagree with critics who claim Columbus did not discover the new world?

Carroll disagrees with critics who claim Columbus did not discover the New World because he argues that Columbus's voyages marked the beginning of sustained European contact with the Americas, fundamentally altering history. While acknowledging that indigenous peoples already inhabited the land, Carroll emphasizes that Columbus's expeditions opened the door for exploration, colonization, and the exchange of cultures and goods. Thus, he sees Columbus's role as significant in shaping modern history, despite the presence of earlier explorers.