According to one traditional definition, aesthetics is the branch of philosophy that deals with beauty, especially beauty in the arts. Examining the pleasing features of the Mona Lisa or a snow-capped mountain, for example, would come under aesthetics. That definition seems too narrow, however, since works of art and natural objects may interest us in other ways than by being beautiful. Instead of evoking admiration of beauty, artists may evoke puzzlement, shock, and even disgust. Consider Picasso's Guernica, a huge (11-ft. × 25.6-ft.) painting in black, white, and grey that he made in response to the slaughter of Spanish civilians by German and Italian warplanes during the Spanish Civil War. Images of disjointed corpses and people screaming dominate the canvas. This work is widely admired ...