Art history professor: Costa criticizes my theories about the distinction between baroque and neoclassical Austrian painting  He argues that since there are no features possessed by all and only the works from a given historical period, assigning works of art to period styles is intellectually bankrupt 
His reasoning can be discounted, however, since his own current theories on the transition from classical to romantic French opera also presuppose such an assignment
The argument rejects the reasoning on which a criticism is based merely on the grounds that that very criticism could be applied to theories of the person who offered it.