Preheat oven to 400 degrees F. Grease a 12-cup muffin tin. In a bowl, stir together flour, sugar, baking powder, baking soda, cinnamon, ginger, and salt. Stir in pears, buttermilk, and oil; blend only until dry ingredients are moistened. Batter will be lumpy. Fill muffin cups 2/3 full and bake for about 15 minutes. Serve warm.