In a bowl, combine the flour, baking powder, baking soda and salt; cut in butter until the mixture resembles coarse crumbs. Stir in buttermilk; knead dough gently. Roll out to 1/2 inch thickness. Cut with a 2-1/2 inch biscuit cutter and place on a lightly greased baking sheet. Bake at 450 °F for 10 to 15 minutes or until golden brown. Remove from pans and cool on wire racks.