Purée 2 cups of the corn with 1 cup of the chicken stock in a food processor or blender and set aside.
In a large, heavy pot set over medium heat, sauté the bacon until crisp. Remove with a slotted spoon and drain on paper towels. Pour off all but 1 tablespoon drippings in pot. Add onions and remaining 2 cups of corn. Sauté, stirring, until onions are softened and corn starts to brown lightly, about 5 to 6 minutes. (If using frozen corn, sauté an extra 2 to 3 minutes to bring out its sweetness.)
Stir in the remaining 1 cup chicken stock and the puréed corn mixture. Reduce heat to a simmer and cook for 10 minutes. Add potatoes, bacon and half-and-half, and cook for 2 to 3 minutes more. Be careful not to let the soup come to a boil once the half-and-half has been added. Season with salt to taste. (Soup can be prepared 1 day ahead to this point; cool, cover and refrigerate. Reheat over low heat.) Remove pot from the heat and cover to keep warm while you prepare the scallops.
Pat scallops dry, then quarter them. Mix smoked paprika, cumin, black pepper and cayenne in a small bowl, then spread mixture on a dinner plate. Coat scallops on all sides with the spice mixture.
Heat enough oil to coat the bottom of a large, heavy skillet set over medium-high heat. When hot, add enough scallops to fit comfortably in the pan and sauté 1 to 2 minutes per side, until just seared. Remove and continue until all scallops are sautéed. Season with salt.
Ladle chowder into 6 soup bowls, then divide the scallops evenly among the bowls. Garnish each serving with chopped chives.