The art commissioned for Tate Modern’s giant turbine hall has been getting bigger and bigger. But is bigger really better? “Art that overwhelms, ‘total immersion’ art, invites suspicion. Some think it intellectually, ethically, and politically dubious. Big art is routinely called “fascistic” – after all, Hitler’s architect Albert Speer dealt in mega-structures and the Nuremberg rally was a triumph of number and mass.”