 Goodman’s argument has been challenged on several grounds. First, the realistic system of representation cannot simply be the standard or customary one, because as an artistic style evolves, spectators are inevitably less accustomed to innovative subjects and techniques than they are to the ones these modify or replace. So if Goodman’s claim were true, an artistic style could never become more realistic, in the eyes of spectators living at the time. But the historical record proves, on the contrary, that it does (Newall 2011: 119–121). Second, Goodman exaggerates the extent to which visual experience is modified by art. Oscar Wilde famously claimed that there had been no fog in London before it appeared in Turner’s paintings. But in fact, writers generally described optical effects long before painters learned to represent them. For example, the spinning highlights on a chariot-wheel were described by the Latin poet Prudentius many centuries before Velazquez captured this effect in paint. Third, even if the art we see does modify our visual habits and influence the resemblances we perceive to some extent, it does not follow that realism cannot consist in resemblance or fidelity to nature. Compare the relationship between theory and observation in science. The growth of scientific knowledge has enabled us to refine our observations of natural phenomena, and these observations have in turn enabled us to test scientific theories. There is nothing suspicious about this interaction between theory and observation, and nothing that should make us wonder whether we possess a “constant and independent” standard, with which scientific theories can be assessed (see §4; of the entry on  theory and observation in science  and  §3 of the entry on   Popper).